ANVESTEGATEQN OF THE FREE RADICAL CGLPQ‘LYMEREZAHW. 6? NAME MHWLNM. EN WI. EEWY SYSTEMS q{Tums {no {Am Dagmn 55 M. S. \iiCELGAI" SEAIE LATT’EASETY LIBRAR Y L] ”“53"” Michigan F- fr University ABSTRACT INVESTIGATION OF THE FREE RADICAL COPOLYMERIZATION OF ITACONIC ANHYDRIDE IN SEVERAL BINARY SYSTEMS by Abdoljalil Mostashari Binary copolymerizations of itaconic anhydride with six comonomers (vinyl pyrrolidine, 4—methoxystyrene, 2—chloro— styrene, 5—chlorostyrene, styrene and divinyl ether) were carried out in tetrahydrofuran using 2,2'—azodiisobutyronitrile as an initiator. Reactivity ratios were determined for the systems itaconic anhydride M1 with methyl methacrylate M2 —-——r1 = 2.25, r2 = 0.1 and itaconic anhydride M1 with 4-methoxystyrene M2 -—- r1 = 0.47, r2 = 0.03 when copolymerized in benzene with 2,2'-azodiisobutyronitrile initiator. Quantitative infra—red analysis was applied to the samples of itaconic anhydride co methyl methacrylate and itaconic anhydride co 4-methoxystyrene for the determination of copolymer compositions. Values obtained by infra-red analysis were found to be in good agreement with the values obtained by elemental analysis of the samples of itaconic anhydride co 4-methoxy- styrene. A model compound, p-secondary butylanisole, was used to prepare the reference calibration graphs for the percent 1 Abdoljalil Mostashari anhydride moiety in the itaconic anhydride co 4—methoxy— styrene since the homopolymer of 4—methoxystyrene was insoluble in acetonitrile. A series of itaconic anhydride Ml-styrene M2 copolymers prepared for the determination of the reactivity ratios of this system were analyzed by infra-red for anhydride moiety content. The r1 and r2 values calculated from the infra—red data were r1 = 0.55 and r2 ==0.02. These values are in reasonable agreement with the values obtained for this system when the composition of these samples was determined by carbon analysis. The quantitative infra—red reference calibration graphs prepared for itaconic anhydride co styrene,itaconic anhydride co 4-methoxystyrene and itaconic anhydride co methyl methacrylate can be used for a quick and accurate infra-red analysis of the composition of these types of copolymers. It has been shown that quantitative infra—red reference calibration graphs can be constructed for use in the determin— ation of the amount of itaconic anhydride moiety in a co- polymer using known mixtures of the two homopolymers. In some cases different concentrations of the single homopolymer, polyitaconic anhydride,can be used to construct these reference calibration graphs but in others different concentrations of polyitaconic anhydride and a model compound similar to the comonomer unit must be employed. INVESTIGATION OF THE FREE RADICAL COPOLYMERIZATION OF ITACONIC ANHYDRIDE IN SEVERAL BINARY SYSTEMS BY Abdoljalil Mostashari A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Chemistry 1966 ACKNOWLEDGEMENT The author wishes to express his sincere appreciation to Professor Ralph L. Guile for his guidance and assistance throughout the course of this work. Appreciation is extended to Dr. M. M. Sharabash for many useful discussions about this work. I wish to acknowledge the financial support of Iran, which has made this work possible. ii TABLE OF CONTENTS INTRODUCTION . . . . . . . . . . . . . . . . . . . . HISTORICAL . . . . . . . . . . . . . . . . . . . . . REAGENTS AND MONOMERS. . . . . . . . . . . . . . . . I - Monomers . . . . . . . . . . . . . . . . . Preparation and Purification. . . . . . . . a - Itaconic anhydride (methylene succinic anhydride) . . . . . . . . b - p—Methoxystyrene (p-vinyl anisole). c - Methyl methacrylate . . . . . . . . II - Initiator O O 0 O O O O O O O 0 O O O O O 0 III — Solvents and Non-Solvents . . . . . . . . . a - Tetrahydrofuran . . . . . . . . . . b - Anhydrous benzene . . . . . . . . . c - Acetonitrile. . . . . . . . . . . . d - Anhydrous ether . . . . . . . . . . IV - Feiser's Solution . . . . . . . . . . . . . V - p-Sec. butyl anisole. . . . . . . . . . . . EXPERIMENTAL . . . . . . . . . . . . . . . . . . . . Part I——Preliminary Copolymerization of Ita- conic Anhydride with Some Comonomers in Tetrahydrofuran . . . . . . . . . . . . Copolymerization of Itaconic Anhydride with Some Comonomers . . . . . . . . . . . . . . Polymerization Technique. . . . . . . . . . iii Page 10 10 10 10 12 15 15 13 14 14 14 15 15 16 17 18 18 TABLE OF CONTENTS - Continued Part II--Reactivity Ratios of Itaconic Anhydride with Methyl Methacrylate and 4—Methoxy— styrene . . . . . . . . . . . . . . . . Copolymerization Process and Technique . . . Analysis of Copolymers . . . . . . . . . . . Calculation of the Reactivity Ratio Values . RESULTS . . . . . . . . . . . . . . . . . . . . . . . I - Copolymerization of Itaconic Anhydride with Methyl methacrylate. . . . . . . . . . . . . II - Copolymerization of Itaconic Anhydride and 4-Methoxystyrene . . . . . . . . . . . . . . III — Reactivity Ratios of Itaconic Anhydride and Styrene. . . . . . . . . . . . . . . . . . . DISCUSSION . . . . . . . . . . . . . . . . . . . . . I - Interpretation of r1, r2 Ratios. . . . . . . A. Itaconic Anhydride-Methyl Methacrylate Copolymerization. . . . . . . . . . . . . B. Itaconic Anhydride-4-Methoxystyrene Copolymerization. . . . . . . . . . . . . C. Copolymerization Reactivity Ratios of Itaconic Anhydride and Styrene. . . . . . II — General Discussion . . . . . . . . . . . . . A. Application of Copolymerization Equations B. The Effect of Ring Substitution in the Reactivity of Styrene Type Monomers . . . C. Infra-red Quantitative Analysis . . . . . SUMMARY . . . . . . . . . . . . . . . . . . . . . . . REFERENCES. . . . . . . . . . . . . . . . . . . . . . iv Page 21 22 25 26 28 29 42 55 64 65 66 68 71 73 74 77 8O 82 LIST OF TABLES TABLE Page 1. Data and Conditions of Copolymerization of Itaconic Anhydride with Some Monomers in TetrahYdrOfurano O O O O O O O O O O O O O O O 20 2. Reactivity Ratio Data for Itaconic Anhydride- Methyl Methacrylate Copolymerization . . . . . 38 5. Reactivity Ratio Data for Itaconic Anhydride- 4-Methoxystyrene Copolymerization. . . . . . . 49 4. Reactivity Ratio Data for Itaconic Anhydride Styrene Copolymerization . . . . . . . . . . . 60 FIGURE I. II. III. IV. VI. VII. VIII. IX. LIST OF FIGURES Page Infra- red spectrum of polyitaconic anhydride (0. 5%). . . . . . . . . . . . . . . 52 Infra— red spectrum of polymethyl methacrylate (0. 5% solution) . . . . . . . . . . . . . . 55 Infra-red spectra of carbonyl absorbances of mixtures of polyitaconic anhydride and poly- methyl methacrylate . . . . . . . . . . . . . 54 A graph of the area of the anhydride peak at 1865 cm-1 against the anhydride moiety con— tent in mixtures of polyitaconic anhydride and polymethyl methacrylate . . . . . . . . . 35 Infra—red carbonyl absorbances of copolymers obtained from copolymerization of itaconic anhydride and methyl methacrylate in benzene (Experiments 1-5 in Table 2). . . . . . . . . 56 Infra—red carbonyl absorbances of copolymers obtained from copolymerization of itaconic anhydride and methyl methacrylate in benzene (Experiments 6-9 in Table 2). . . . . . . . . 57 Copolymer composition curve of itaconic anhydride—methyl methacrylate copolymeriza- tion. . . . . . . . . . . . . . . . . . . . . 59 Graphical solution of copolymerization equa— tion for itaconic anhydride-methyl methacry— late copolymers (Intersection method) . . . . 40 Graphical solution of copolymerization equa- tion for itaconic anhydride-methyl methacry— late (Fineman and Ross method). . . . . . . . 41 Infra- red spectrum of p- sec. butyl anisole (0. 5% solution) . . . . . . . . . . . . . . . 44 vi LIST OF FIGURES - Continued FIGURE XI. XII. XIII. XIV. XVI. XVII. XVIII. XIX. XXII. Infra-red spectra of carbonyl absorbances of mixtures of polyitaconic anhydride and p- sec. butyl anisole . . . . . . . . . . . . . A graph of the area of anhydride peak at 1865 cm"1 against itaconic anhydride moiety content in mixtures of polyitaconic anhydride and p-sec. butyl anisole . . . . . . . . . . Infra-red carbonyl absorbances of copolymers obtained from copolymerization of itaconic anhydride and 4-methoxystyrene in benzene (Experiments 1-5 in Table 5) . . . . . . . . Infra-red carbonyl absorbances of copolymers obtained from copolymerization of itaconic anhydride and 4-methoxystyrene in benzene (Experiments 6-9 in Table 5) . . . . . . . . Copolymer composition graph for itaconic anhydride—4-methoxystyrene c0polymerization. Graphical solution of the copolymerization equation for itaconic anhydride-4—methoxy- styrene copolymers (Intersection method) . . Graphical solution of copolymerization equa— tion for itaconic anhydride-4-methoxystyrene copolymers (Fineman and Ross method) . . . . Infra-red Spectra of polyitaconic anhydride (Initiated with benzoyl peroxide) solutions with different concentrations. . . . . . . . A graph of the areas of anhydride peak at 1865 cm-1 versus the itaconic anhydride moiety percent . . . . . . . . . . . . . . . Infra-red spectra of itaconic anhydride—sty— rene copolymers (Experiments 1-4 in Table 4) Infra-red spectra of itaconic anhydride—sty- rene copolymers (Experiments 5—8 in Table 4) Copolymer composition graph of itaconic anhydride styrene copolymers . . . . . . . . vii Page 45 46 47 48 50 51 52 56 57 58 59 61 LIST OF FIGURES XXIII. XXIV. FIGURES - Continued Page Graphical solution of copolymerization equation for r1, r2 values in copolymeriza- tion of itaconic anhydride—styrene (Inter— section method). . . . . . . . . . . . . . . 62 Graphical solution of copolymerization equa- tion for itaconic anhydride—styrene copoly- mers (Fineman and Ross method) . . . . . . . 63 viii INTRODUCTION Free radical copolymerization of itaconic anhydride with various monomers have been studied in this laboratory (20,21). The present work was initiated to extend the studies on the copolymerization of itaconic anhydride and to determine the reactivity ratios for the two systems itaconic anhydride- methyl methacrylate and itaconic anhydride-4-methoxystyrene. Quantitative infra-red analysis of itaconic anhydride type copolymers had been applied in a limited number of cases (21). Further work on the quantitative infra-red analysis of the copolymers of itaconic anhydride-styrene and an extension of this technique to itaconic anhydride-co-methyl methacrylate and itaconic anhydride—co-4-methoxystyrene appeared desirable. HISTORICAL Although the phenomenon of polymerization of organic compounds has been known for over a century (1), the simul- taneous polymerization of two or more monomers was not investigated until around 1911, when the copolymerization of isoprene and butadiene was patented (2). A year later Kandakov published a paper on copolymerization of butadiene and dimethyl butadiene (3). The initial work on copolymeri- zation emphasized the study of the properties of copolymers and very little was reported on the mechanism and kinetics of the reactions. During the 1950's it was found that monomers differed in their tendency to enter the copolymers, and that copolymer samples withdrawn at different degrees of conversion contained the two components in different ratios (4). It was also reported that maleic anhydride, stilbene, isobutylene and fumaric ester, compounds which homopolymerize with great difficulty, easily form copolymers with each other or with other polymerizable monomers, such as styrene and vinyl chloride (5,6,7). Kinetic work on copolymerization was started in the mid- thirties by Dostal (8). In his treatment, he assumed that the rate of addition of monomer to a growing free radical chain depended only on the nature of the end group on the radical chain. Thus monomers M1 and M2 lead to radicals of types M1* and M2*. There are four possible ways in which monomer can add: reaction rate * 'X' * M1 + M1 ‘—_*’M1 kll [M1] [M1] * * * M1 + M2 "—EV'Ma k12 [M1] [M2] * * * I M2 + M1 ‘—-*'M1 k21 [M2] [M1] * * * M2 + M2 -——*’M2 R22 [M2] [M2] Since four independent rate constants were involved, Dostal made no attempt to test his assumption experimentally. In 1959 Norrish and Brookman (9) published an experimental study of copolymerization of styrene and methyl methacrylate which provided reliable data for a theoretical analysis of the co- polymerization reaction. The next important step was contributed by Wall (10).in 1941, who suggested that the chemical composition of a co— polymer would depend only upon the relative reactivities of the two monomers towards the two radicals. hlzrl E22=r2 II After several unsuccessful approaches, the kinetics of co— polymerization was elucidated in 1944 by Alfrey (11), Mayo (12), Simha (15),and Wall (14). To Dostal's reactiOn scheme they added the assumption of the steady state applied to each radical type. This steady state required that each type of free radical must be maintained at a certain fixed characteristic concentration i.e., each type of radical disappears into a polymer chain at the same rate at which it is formed. kia [M:]IM2] = k21 [M:][M1] III which states that the rate of conversion of M1 to M2 must * 9(- equal that of conversion of M2 to M1. The rate of disappearance of monomer M1 is given by: 4&4 = 1mm?) [M11 + k21[M:] [M11 IV similarly, the rate of disappearance of monomer M2 is given by: -d—dL%l-ai = kgg [M2] [M2] + k12 [M1] [M2] V Since the relation between.M¢] and [M2] is given by the steady state expression (Eq. III), the ratio between the rates of disappearance of M2 and M1 could be written in the following form: k d[MJl = .IMJ]. . (it) [M1] + [M2] VI d[M2] [M2] (£22) [M2] + [M1] 21 If one substitutes the reactivity ratios of Wall (II) in Eq. (VI) one gets the following: Qlflil.= Iflil . r1IM1] + IMal VII d[M2] [M2] r2[M2] + [M1] Equation (VII) is the differential form of the copolymerization equation. However, if the percentage of conversion of mono- mers into copolymers is low, the concentration of each of the monomers, M1 and M2 at this low conversion will be nearly equal to the initial concentration of monomers, and the ratio of concentrations of the monomers in the copolymers, equal to the ratio of disappearance of the monomers. Qiflil._ .Ti - VIII dlMa] m2 Hence, Eq. VII could be written as follows: 911. = fll . rlMl + M2 IX m2 M2 r2M2 + M]. It should be recognized that IX is valid only for very low conversions, otherwise the integrated form of Eq. VII must be used (12) O iflal _ 2L 1-p(M /M2) r2 = log [MEL [#0 10: inhfi/glg) ] x 1M1) -p M M 109 [M11 + [ 109 1-p(M§/M§> A where: p = (1 - r1)/(1 - r2) Copolymerization data for the cyclic anhydride monomer maleic anhydride has been reported by numerous investigators (15-19), but the only reported data on itaconic anhydride, has been from this laboratory (20,21). The copolymers of itaconic anhydride, however, have been the subject of in- creasing patent and industrial interest (22,25). A variety of analytical methods have been used to de- termine the composition of various copolymers. These methods differ depending on the copolymer to be analyzed. If the carbon percent of one of the monomers is much higher than the other, or one monomer contains elements such as halogens, sulfur or nitrogen, elemental analysis may be used for co- polymer composition determinations. High frequency and potentiometric titrations of the acid function in acid and anhydride containing copolymers has also been used (24,25). Spectrophotometric methods (especially infra—red and ultra— violet) have recently been employed for copolymer composition determinations (26,27,28). Measurement of the anhydride peak in the infra-red spectra of the copolymers containing such an anhydride moiety was first utilized in this laboratory (21) to determine the composition of itaconic anhydride copolymers. REAGENTS AND MONOMERS 10 I - Monomers Preparation and Purification a - Itaconic anhydride (methylene succinic anhydride) Itaconic anhydride was prepared from itaconic acid by dehydration using acetyl chloride. The crude anhydride ob- tained had a melting point of 68—69OC. and was recrystallized from dry chloroform to give pure anhydride (m.p. 68.5.: 0.2OC.). Itaconic anhydride may also be prepared from itaconic acid using thionyl chloride (29), phosphorous pent- oxide (50), acetic anhydride (51) or 98% sulfuric acid (52). Itaconic acid and anhydride along with citraconic acid and anhydride are prepared from the distillation of anhydrous citric acid (55), or the distillation of concentrated aqueous solution of citric acid under vacuum at 250°C. (54). Itaconic acid is commercially produced by submerged culture fermen- tation of glucose media by "Aspergillus terrus“. b - 4-Methoxystyrene (p-vinyl anisole) 4—Methoxystyrene (Monomer-Polymer Laboratories, Borden Chemical Co.) containing 1% hydroquinone inhibitor was washed with 5% sodium hydroxide to remove the inhibitor. It was then stored over anhydrous magnesium sulfate for 5 days. The dry monomer was then flash distilled in a Rotavapor at a reduced pressure of 2-4 mm., and the fraction with the boiling point of 54-56OC. was collected as monomer. The distilled unin— hibited monomer was then stored over anhydrous sodium sulfate, in a refrigerator, and used as soon as convenient (usually in 11 less than 24 hours). To insure that no polymerization had occurred before use, the monomer was tested with methanol. Poly 4—methoxystyrene is precipitated as a white precipitate by methanol, and the monomeric 4—methoxystyrene remains in solution. Some of the 4—methoxystyrene was prepared in this labora- tory by the following two step procedure: Step I - Synthesis of p-methoxycinnamic acid (55) One mole (156 grams) of anisaldehyde was added to one mole (126 grams) of malonic acid and one mole (95 grams) of aspicoline in a three neck flask fitted with a reflux condenser and a mechanical stirrer. The mixture was heated over a boil— ing water bath for two to three hours. At the end of this period, evolution of carbon dioxide ceased, and after cooling a solid crystalline mixture was obtained. The solid product was then dissolved in a minimum amount of ammonium hydroxide solution. This solution was boiled with 1~2 grams of de- colorizing charcoal and then filtered. To the cooled filtrate sufficient amount of concentrated hydrochloric acid was added, with stirring, to make the solution acid to Congo red. p-Methoxycinnamic acid precipitated. It was filtered and washed with several portions of cold water and dried. The melting point was 167—1680C. Step II - Decarboxylation of p-Methoxycinnamic acid (56). Decarboxylation was carried out in a three neck distill— ing flask fitted with a thermometer and an adaptor attached 12 to a condenser. Sixty grams of p-methoxycinnamic acid in 100 milliliters of quinoline were heated in the presence of 5 grams of refined copper powder. The reaction mixture was allowed to distill at such a rate that during the bulk of the reaction, the temperature of the vapor remained below 2200C. The reaction was considered to be complete when the temperature of the vapors reached 2570C. (boiling point of quinoline). At the end of the reaction,a resinous residue (probably polymer) was left in the flask. To the distillate, containing 4-methoxystyrene, one gram of hydroquinone was added to inhibit polymerization. It was then dissolved in ether and washed with cold 2.4 N. hydrochloric acid and water to remove the quinoline. The ether was removed by distilla- tion under reduced pressure at room temperature, and the product was dried over anhydrous calcium sulfate. The impure product was then fractionally distilled under vacuum, and the fraction boiling at 98-101 at 9—10 mm. was collected. To the 4-methoxystyrene thus prepared 0.1% hydroquinone was added as inhibitor. The overall yield was 50%, based on anisaldehyde. Yields as high as 50% have been reported in the literature. c - Methyl methacrylate Methyl methacrylate (Matheson, Coleman and Bell Co.) (b.p. 100—1OC.) containing hydroquinone was washed rapidly with 5% sodium hydroxide solution and stored over anhydrous sodium sulfate in a refrigerator for approximately three days. The monomer was distilled and the fraction having the boiling 15 point of 24-250C. at 7-8 mm. was collected, and stored over anhydrous magnesium sulfate. Before using methyl methacrylate in any polymerization, it was tested for the presence of polymeric methyl methacrylate. A small volume of the monomer was added to an 80% aqueous solution of ethanol. Since the polymethyl methacrylate is insoluble (57) in the solution, the absence of a precipitate indicated that the monomer was free from polymer. II - Initiator 2,2'—Azobis—(2—methylpropionitrileF-2,2'(azodiisobutyro— nitrile(CH3)2C(CN)N:NC(CN)(CH3)2) (Eastman Organic Chemicals) was dissolved in an aqueous solution of ethanol (80%) and filtered. The filtrate was then diluted with distilled water. The diisobutyronitrile was precipitated, collected and dried in a dessicator under vacuum at room temperature. III - Solvents and Non—Solvents a — Tetrahydrofuran Tetrahydrofuran was stored over potassium hydroxide pellets for two weeks. It was stored over metallic sodium for 5-7 days. The tetrahydrofuran was then refluxed with lithium aluminum hydride for about twelve hours and distilled. A fraction boiling at 64-650C. was collected for use. Since tetrahydrofuran is highly hygrosc0pic, a freshly distilled portion was used for each copolymerization reaction. 14 b — Anhydrous benzene Benzene was washed with two to three consecutive batches of concentrated sulfuric acid to remove the thiophene and other impurities. The benzene was then washed with 10% solu— tion of sodium bicarbonate to remove the traces of acid. It was then washed several times with distilled water until the washings were neutral to litmus. Thiophene free benzene was stored over anhydrous calcium chloride and then over sodium wire. The benzene was finally refluxed over metallic sodium for 12 to 24 hours and distilled, a fraction collected at 80-80.50C. at atmOSpheric pressure, was used. c - Acetonitrile Spectrograde acetonitrile (Matheson, Coleman and Bell Co.) was stored over phosphorous pentoxide followed by reflux- ing for approximately six hours over fresh phOSphorous pent- oxide. It was distilled and the fraction boiling at 820C. at ordinary pressure was collected for use. d — Anhydrous ether Anhydrous grade diethyl ether was stored over sodium metal for about a week. It was refluxed over lithium-aluminum hydride for 5 to 10 hours, and distilled. The fraction boiling at 540C. at ordinary atmospheric pressure was collected for use. 15 IV - Fieser's Solution Fieser's solution was prepared by dissolving 20 g. of potassium hydroxide in 100 milliliters of distilled water (freshly distilled from all glass equipment) and adding 2 g. of sodium anthraquinone-B—sulphonate and 15 g. of commercial sodium hyposulphite (85 percent) to the warm solution, which was stirred until all the reagents had dissolved. The ex- haustion of this solution is indicated by the change in color from blood red to dull red or brown, or when a precipitate due to sodium hydrogen sulfate appears (58). N328204 + 02 + H20 NaHSO4 + NaHSOS V - p-Sec. butyl anisole (59) One mole (108 grams) of anisole and 0.75 moles (105 grams) of sec. butyl bromide were dissolved in 100 ml. petrol— eum ether. The solution was placed in a dropping funnel and was gradually added to 0.125 moles (17 grams) of anhydrous aluminum chloride suspended in 100 milliliters of petroleum ether, at room temperature. The reaction was allowed to pro- ceed for three to four hours. The intensely colored reaction mixture was then poured in to 50 milliliters of concentrated hydrochloric acid and approximately 200-g. of ice. A two layer system resulted. The ether layer, was separated from the aqueous acidic layer. The petroleum ether was removed from the ether layer by distillation and the residue was fractionally distilled under vacuum. The fraction boiling at 24—25OC. at 22.5 = 5 mm., nD 1.514 was the p-sec. butyl anisole. EXPERIMENTAL 16 PART I Preliminary Copolymerization of Itaconic Anhydride with Some Comonomers in Tetrahydrofuran 17 18 Copolymerization of Itaconic Anhydride with Some Comonomers Itaconic anhydride was copolymerized with vinyl pyr- rolidine, 4-methoxystyrene, styrene, 2-chlorostyrene, 5-chlorostyrene and divinyl ether in tetrahydrofuran. 2,2'-Azodiisobutyronitrile was used as an initiator. Initial concentration was 50:50 of itaconic anhydride and the co- monomer . Polymerization Technique A calculated amount of itaconic anhydride was dissolved in 250 milliliters of tetrahydrofuran in the reaction vessel. After solution of the anhydride,the approximate amount of the comonomer (in all cases it was liquid), and 200 milligrams of the initiator were added. Then the reaction flask was heated in an oil bath to the reflux temperature of tetrahydrofuran. The reaction vessel was a 500 ml. two neck round bottom flask. Through the small, side neck (3 10/14) a nitrogen bubbler was inserted. To the center neck (S 24/40) a reflux condenser was attached which was equipped with a drying tube filled with anhydrous calcium chloride. The reaction was stirred con— tinuously throughout the reaction period by a magnetic stirrer. The polymerization was allowed to proceed for 12-14 hours. The flask was then removed from the oil bath, and the polymer solution was transferred to the distilling flask of a Rota— vapor and the solvent was evaporated to obtain an optimum concentration for precipitating by a non—solvent. The polymer 19 was then precipitated using a non-solvent such as: anhydrous ether, petroleum ether, or a mixture of both, such that an easily handled precipitate was obtained. There was a critical optimum concentration, below which, a very small amount of precipitation occurs, and above which, polymer will be separated as a viscous liquid which can not be removed by filtration. The precipitated polymers were filtered, dried, and extracted with benzene to remove unreacted amounts of anhydride. They were then dried in an Abderhalden drying pistol under vacuum at the reflux temperature of acetone. The polymers were weighed to 10.1 gram and the percentage of conversion of monomers to copolymers were calculated for each copolymer. Table 1 gives a summary of initial composition of monomers, percentage of conversion and conditions for the above men- tioned copolymerizations. 20 Hmsum ma umnum .umm fi.NH N.m 00.5 N.HH H>0H>Ha 0 mcmumum 0N nonum .umm o.om fi.m 0m.m m¢.¢ IOHOHBUIM m mamHMum 0m nonum .umm 0.0H o.H 0m.m m¢.¢ IOHOHEUIN w umnum Hmnumflo can 0 umnum .umm 0.Nfi 0.4 00.ma 0.0a mamumum m “mnum Hanumflo 4m 0am 0.0w 0.0a 0a.0m 0.0a mamumum Hwnuw .umm Imxonumzlw N #N Hmnum .umm o.aa m.m mm.oa m.ma mcfloflaou luwm H>GH> a mu: cowumuflmflu unmonmm umfihaom um um m2 Hmnfisz mafia long How scamnm> m0 m2 HE HmEOGOEOU ucmfi ucm>aomlcoz Icou unmflm3 Iflummxm GMHSHOHGMSMHumB :H mumsocoz meow LuHB mUHH©>£c< UAQOUMUH mo COHummflnmfihaomou mo mGOHuHUGOU paw mama .H magma PART II Reactivity Ratios of Itaconic Anhydride with Methyl methacrylate and 4—Methoxystyrene 21 22 Copolymerization Process and Technique A series of copolymerizations of itaconic anhydride (M1) and each of the other two comonomers (M2) were made in benzene at the molar ratio of: Ml/Ma; 1/9, 2/8, 5/7, 4/6, 5/5, 6/4, 7/5, 8/2, 9/1. The copolymerizations were carried out in a 500 milliliter, two neck flask, which was fitted with a nitrogen inlet and a reflux condenser. Gaseous nitrogen from a cylinder of puri- fied nitrogen was passed through Fieser's solution in order to remove traces of oxygen and then dried by anhydrous calcium chloride. The apparatus was protected against moisture using a drying tube filled with anhydrous calcium chloride. The appropriate amount of itaconic anhydride was dis- solved in 200 milliliters of anhydrous benzene at room tempera- ture with stirring. A calculated amount of comonomer was then added and oxygen was removed from the apparatus and reactants using a sweeping process (21). The total amount of both monomers in the reaction was 0.1 mole and the solvent 200 milliliters resulting in a concentration of monomer of 0.5 mole liter-l. Two hundred milligrams of purified 2,2'—azobis- isobutyronitrile was used (0.1%*wt/volume) to initiate the copolymerization. The temperature of the reaction was increased to reflux of the solvent and maintained at this temperature throughout copolymerization. There was almost no induction time and a slight turbidity was observed almost immediately when the solvent began to reflux. An exception to this was 25 was noted in the case of itaconic anhydride—methyl methacry- late Ml/Mg = 1/9, since the polymer was soluble in the solvent. When the appropriate percent of polymerization (judged by the amount of precipitated copolymer or by the time of reaction in the case of copolymerization of methyl methacrylate) had occurred, the flask was taken out of the oil bath, and the content was transferred to a bottle and im- mersed in a dry ice-acetone mixture to quench the reaction. The solidified mixture was then allowed to thaw, and copolymer was separated by centrifugation and washed several times with hot benzene to remove traces of unreacted monomers. The co- polymer was then dried, first in a dessicator under reduced pressure (20-25 mm) at room temperature, and then in Abderhalden drying pistol under vacuum, at boiling point of acetone (56°C.) for twenty-four hours. In the latter drying process, any residue of itaconic anhydride sublimed out of the copolymer. The dry polymer was weighed and the percent of c0polymerization was calculated as follows: Percent of copolymerization = (weight of copolymer/total weight of monomers) x 100 Analysis of Copolymers To find the reactivity ratios, it was necessary to de- termine the mole fraction of itaconic anhydride (M1) and the mole fraction of the comonomer (M2), in the copolymer. In order to get the mole fractions in the copolymer, quantitative 24 infrared analysis of the copolymer was obtained using a "Perkin-Elmer 257B" spectrophotometer, and matching sodium chloride cells. The scanning was done at low Speed (8 min./ spectrum), and the slit opening was set at 5. The thickness of the solution in cell was 0.5 mm. The analysis of the amount of itaconic anhydride moiety in the itaconic anhydride co methyl methacrylate polymer, was carried out in the follow- ing manner: polyitaconic anhydride - 0.05 grams and poly- methyl methacrylate 0.05 grams, were each dissolved in 10 milliliters of anhydrous acetonitrile in volumetric flasks. The 0.5% solutions thus prepared were used to make a series of solutions in the following proportions: Polyitaconic anhydride 0 0.4 0.8 1.2 1.6 2 Polymethyl methacrylate 2 1.6 1.2 0.8 0.4 0 Total volume 2 2 2 2 2 2 percent anhydride 0% 20% 40% 60% 80% 100% The standard solution for the determination of itaconic an- hydride moiety in the copolymer of itaconic anhydride with 4—methoxystyrene, was prepared and diluted in the above described manner, using 0.5% solution of p-sec. butyl anisole (A model compound of poly—4-methoxystyrene) in the place of 4-methoxystyrene (which was insoluble in acetonitrile). The standard solutions for the determination of the composition of itaconic anhydride co styrene polymer were prepared using a 0.5 percent solution of polyitaconic anhydride (initiated with benzoylperoxide) and diluting it with anhydrous aceto- nitrile to 80%, 60%, 40%, 20% of the original concentration. 25 Infra—red spectra of these three series were obtained. Peak areas of the anhydride peaks at 1865 cm‘1 for different con— centration of anhydride were measured. For these measurements a "Keuffel & Esser 620022" Planimeter was used. Plotting the known percentage of polyitaconic anhydride in the standard solutions versus the peak areas, gave three straight line graphs, which were used as standard reference graphs, assumed to be related to the percent of anhydride moiety in the various copolymers. In the same manner, 0.5% solutions of different copolymers were made, by dissolving 0.01 grams of each copolymer in 2 ml of anhydrous acetonitrile. The infra-red spectra of these copolymers were obtained and 1 were plotted the peak areas of the anhydride peak at 1865 cm’ against the itaconic anhydride moiety content to construct a calibration curve. The infra-red Spectra of the copolymers were obtained and the percentages of itaconic anhydride moiety in the copolymers were determined using the standard graph. From the percent by weight of the itaconic anhydride moiety, the mole fractions (ml and mg) were calculated according to the following procedure. Let A = percent of itaconic anhydride moiety B = 100-A = percent comonomer moiety M = molecular weight of comonomer 112 = molecular weight of itaconic anhydride A/112 = x number of moles of anhydride moiety in 100 grams of copolymer B/M = y number of moles of comonomer moiety in 100 grams copolymer x+y = 2 total number of moles of monomer moieties in copolymer 26 mole fraction of each monomer is simply obtained by x/z = m1 Y/Z=1-m1=m2. Calculation of the Reactivity Ratio Values Copolymerization equation (I), gives the relationship between reactivity ratios r1 and r2 and initial and final concentration of monomers in the reaction mixture. d IMJI _ IMJI . rLIMi] + [MZJ d[M2] [M2] r2[M2] + [M1] assuming very low conversions 9.1.:ng :21; MM +M II m2 d[M2] M2 . r2[M2] + [M1] where M; = mole fraction of itaconic anhydride in the initial reaction mixture M2 = mole fraction of the comonomer in the initial re— action mixture m1 = mole fraction of itaconic anhydride moiety in the copolymer m2 = mole fraction of the comonomer moiety in the copolymer r1 = reactivity ratio for itaconic anhydride radical r2 = reactivity ratio for the comonomer radical Assuming: Equation (II) can be rearranged into the following forms: r2 = F(1/f(1 + Frl) - 1) III F. _ _ £2- 2 f(f 1) — rlf r IV From equation III, it is readily concluded that any experimental 27 values of F, f are represented as straight lines, when r1 is plotted versus r2. Assumed values of r1 (+0.1, 0, -0.1) were therefore substituted in equation (III), and plotted against observed values of re. Using different values of r; and r2, for different compositions of the copolymer, several straight lines were obtained. The point of intersection of these lines is at the r1 and r2 values for a system. Besides the above mentioned method of intersection, equation IV can also be 2 used in determination of r1, r2 values, by plotting %—- against %(f - 1). This results in a straight line graph, the slope of which is equal to r1 and the value of the point of 2 intersection of the extrapolated line with the %—-axis is —r2. This method was first suggested by Fineman and Ross (40). RESULTS 28 29 I -Copolymerization of Itaconic Anhydride with Methyl methacrylate 5O Itaconic anhydride was copolymerized with methyl methacrylate in benzene, using 2,2'-azobisisobutyronitrile as initiator. The copolymers were analyzed by infra-red spectrophotometry, following the changes in the area of anhydride carbonyl peak at 1870—1850 cm‘l. It should be noticed that cyclic anhydrides have two absorption peaks in this area, one at 1800—1760 cm-1 (5.56-5.68 u), and the other at 1870—1850 cm‘1 (5.55-5.46 0), (41). Methyl methacrylate shows a peak at 1750-1755 (5.71- 5.76 u). Figures I and II Show the spectra of polyitaconic anhydride, and polymethyl methacrylate respectively, while Figure III shows the infra-red of C=O stretching absorption peaks of the different mixtures of 0.5% solution of poly- itaconic anhydride and polymethyl methacrylate. The areas of the peaks at 1865 cm"1 were measured, and plotted against the anhydride percent, as shown in Figure IV. Figures V and VI Show the infra-red carbonyl peaks of the co- polymers obtained from different copolymerization experiments. 1 were measured and the respective The areas of peaks at 1865 cm“ anhydride moiety percents were obtained from the calibration curve (Figure IV). From the percentages of anhydride moiety in the copolymers, the mole fractions were calculated. The data from which the reactivity ratios were determined are Shown in Table 2. A copolymer composition graph was drawn plotting ml versus M1 (Figure VII). The differential form of the co- polymerization equation was solved for r1, r2 values, for every copolymerization carried out in this series, and r1,r2 were de- termined graphically by the method of intersection (Figure VIII). 51 The rearranged copolymerization equation was also used to 2 plot %-versus %(f—1), and the r1, r2 values were determined by the Fineman and Ross method (Figure IX). 52 .ARm.ov mofluomncm oecoomuflwaom mo Esnuowmm UmHIMHMCH .H muomflm 00w OOOH AHIEUV hocmsmmnm OONH coed oomfi coma OOON a . . . ~ 1 <3 0 (%) eoueqqrmsuexm OOH .AGOHUSHom Rm.ov mumHmuomnumE Hmnumemaom mo Esuuommm UmnlmumcH .HH musmflm AHIEUV mocmsvmnm 00m 0000 OONfi oowa anowd coma OOON A a 4 . A O N 55 0 <4 (%) eoueqqtmsuexm I O (O 0H .54: .mumHmuomnumE Hmnumfimaom tam mpflnphzcm UHcoomuflmaom mo monsuxfle mo mwocmnuomnm Hmconnmo m0 00.50me UmulmumcH .HHH musmflm I. 55 100 80' 4.) C: m 0 H 8, 60» w . 4.) 0 W4 0 E m 0 H 3-4 3’. g 40. c m 0 ‘r-i c 0 U m 4..) H 20— O ‘r . A 1 4—4 l O 1 2 5 4 5 Peak areas sq. cm. Figure IV. A graph of the area of the anhydride peak at 1865 cm’1 against the anhydride moiety content in mixtures of polyitaconic anhydride and polymethyl methacrylate. le .AN magma SH mud munofiflnmmxmv mamNch CH mumHMHomgumE Hmsuwa tam moflupmnnm oecoumufl mo COHpMN lemmamaomou Eoum UmCHmqu mumfihaomoo mo mmonmnuomnw Hmconumo UmulmumcH .> wusmflm O N <3 0 (%) aoueqqtmsuexm .00 .O@ OOH 57 .AN magma CH mum munmfiflnmmxmv meNch :H mumamnomnpmfi ahsumfi paw mpflnohncm oacoomuw mo coaumu lemmawaomoo Eoum Uwcflmqu mumfihaomoo mo mwucmnnomnm Hmconnmo pmulmnmcH .D. .H> wusmflm low .OOH (%) eoueqqtmsuexm 58 mumHmuomnumZ ahnumzlmpflunmncd UAQOUMuH How muma OHumm >ua>flu0mwm .umENHomoo CH mnflunmncm oasoumufl m0 comuumum mac: n HE .musprE cofluommn CH mnfluowncm UHGOUMuH mo coauomum mHoE HMHuHGH u as mmm.o em m.m 00.0 oma.o m.o mo.oa m oom.o Hm ¢.m H¢.N mmN.o m.o mm.m m >mm.0 mm m.m m>.« oma.o 5.0 «m.> S Nom.o mm H.m >¢.N mom.o m.o N>.m m owm.o mu o.m em.m 0mm.o m.o om.m m mm>.o on m.m mw.m mmm.o 0.0 m¢.¢ 0 m>©.o ob >.N m>.m 0mm.o m.o mm.m m 0am.o 0m m.m oo.m moN.o m.o 0N.N N mum.o ow >.H SH.N 0mm.o a.o NH.H a GOAUUMHE unmonmm mumfloz .80 .Um unmoumm mfimnw mGOHuomuh mfimuo Hwnasz_ 0H0: mpflunmncd mwnfi coamum>aoo pamflw 0H0: ucwg Hz uaaoumuH xmmm a: Iflummxm coaumuflumfihaomou .N OHQMB Mole fraction of itaconic anhydride moiety in copolymer ml 59 0.0; J A Mole fraction of itaconic anhydride in reaction mixture- 0.2 n \‘ 0.5 0.4 0.5 0.6 0.7 M1 0.8 0.9 1.0 Figure VII. Copolymer composition curve of itaconic anhydride-methyl methacrylate co- polymerization. l | . I / i : . | f I ’ l 2 r1 | | f/ l 1 f l l r; = 2'.28 :. r2 = 0.06 I | / | O l 0.1’7 / i *7 41 l 2.0 ”1.0 0 +1 +1 1:2 Figure VIII. Graphical solution of copolymerization equation for itaconic anhydride-methyl methacrylate co- polymers (Intersection method). 41 r1 slope = 2.25 0.1 r2 (NI— Pr tflw (fit CD \1 (I) Figure IX. Graphical solution of copolymerization equation for itaconic anhydride-methyl methacrylate (Fineman and Ross method). 42 II -Copolymerization of Itaconic Anhydride and 4-Methoxystyrene 45 Itaconic anhydride was copolymerized with 4-methoxy- styrene in benzene, using 2,2'-azobisisobutyronitrile as initiator. The copolymers were analyzed by infra-red Spectro— photometry method, following the changes in the anhydride peak at 1865 cm‘l. A standard curve was plotted using mix- tures of polyitaconic anhydride and p-sec. butylanisole (a model compound for 4-methoxystyrene), at different ratios. Figure X shows the spectrum of p-sec. butylanisole. The spectra of mixtures of 0.5% of these two are shown in Figure XI. Figure XII shows the standard curve obtained by plotting percent of polyitaconic anhydride in the mixture against peak areas of anhydride peak at 1865 cm‘l. The infra-red spectra of the copolymers obtained from different copolymerization experiments are shown in Figures XIII and XIV. By measuring the areas of the anhydride peak of the Spectra of the various copolymer samples and comparing the areas with the standard curve, itaconic moiety percents were obtained for each co- polymer. Table 5 shows the data from which the reactivity ratios were calculated. A copolymer composition graph was drawn plotting m1 against Ml (Figure XV). The composition graph shows an azeotrope where initial composition of reaction mixture and composition of the copolymer is equal. The co- polymerization equation was graphically solved (by the inter- section method), for r1, r2 values (Figure XVI). Also, the graphical method of Fineman and Ross was utilized to determine the reactivity ratios (Figure XVII). 44 .ACOApSHom Rm.ov maomflcm Hausa .melm mo Eduuummm UmunmumcH .N musmflm AHIEUV wocmsvmnm oom OOOH OONH ooea coma coma OOON ~ y u i. .ON .9. (%) eoueqqtmsuexm Om 00 OOH 45 .maomflsm Huang .ommlm Ucm wnaupmncm Uflcoomuflmaom mo mmHSuxHE mo mmocmnnomam Hmsonnmo Mo muuowmm @mWImumcH .Hx madmam Low .Om K0004“ Row 0 N00 ROUV 9\ON (%) eoueqatmsuexm i t 4005.. 100 90~ 80’ 70? 60— 50+ 40+ 50' Itaconic anhydride moiety percent 10- l L 2 5 4 5 6 Peak area cm2 Figure XII. A graph of the area of anhydride peak at 1865 cm-1 against itaconic anhydride moiety content in mix- tures of polyitaconic anhydride and p-sec. butyl anisole. 47 .Am magma CH mud mucmfiflummxmv mamNch CH mammMumSXOSumEI$_Ucm moflupmscm Uflcoomufl mo COHuMNHHwENHom loo Eoum Umnflmuno mumfihaomoo mo mmucmnuomnm Hmconumo UmulmumcH .HHHx mesmem r“ H. 0 low M P U S m TL- 1 q E U D .00 e m w 00 .00 OOH 48 .Am magma ca mum mucmEHummxmv mcmncmn CH mamuhum Imxonpmfild tam wofluomsnm Uflcoomufl mo coeumwfluwfihaomoo Eoum UmCHMqu mnmfi>aomoo mo mmocmnnomnm stonumo UmulmumcH .>Hx mesmem 49 .umfihdomou SH muwflofi mvfluvmncm UHnoomufl mo coauownm man: u HE .muduxfla GOfluummH mzu CH wbflnvhncm oacoumufl mo noauomum mHoE HmwuHCH n 02 00>.0 0.05 0.0 00».0 0a.00 00.0 000.0 0.0 00.00 0 000.0 0.N0 0.0 0N0.0 00.00 N0.0 000.0 0.0 00.0 0 000.0 0.00 0.0 000.0 00.00 No.0 000.0 0.0 00.0 0 000.0 0.00 0.N 000.0 00.00 00.0 0N>.0 0.0 N>.0 0 000.0 0.00 0.N 000.0 00.00 00.0 000.0 0.0 00.0 0 .000.0 0.N0 0.N III: III: 00.0 000.0 0.0 00.0 0 000.0 0.00 0.N 000.0 00.00 00.0 0N0.0 0.0 00.0 0 .000.0 0.00 0.N 000.0 00.00 00.0 000.0 N.0 0N.N N 000.0 0.00 0.N 000.0 00.00 00.0 0N0.0 0.0 NH.H H HE R mumfloz .EU .00 HE unmoumm unmonwm Educ 0H0: mEmuw Hmnfisz mnwuvm£c< mmud connmu GOHmnm> UHmflN S ucmfi UHQOUMUH £000 1:00 Iflummxm coaumuflumfi>aomoo mcmumummxonpoZI0lmUHHwhncd UflCOOMHH How mvmq OHumm mufl>fluommm m magma Mole fraction of itaconic anhydride moiety in copolymer- ml 1.0 0.2 0.1 50 v I l L 1_I J J I 0.1 0.72 05 c.4 6,5 6.6 0.7 0-8 09 M1 10 Initial mole fraction of itaconic anhydride in the reaction mixture Figure XV. Copolymer composition graph for itaconic anhydride-4-methoxy— styrene copolymerization. 51 07— 030 0.5“ r1 0.4v 0.0. 0.1 0.52 0.05 r1 r2 Figure XVI. 0 +0.5- r2 Graphical solution of the copolymerization equation for itaconic anhydride-4-methoxystyrene copolymers (Intersection method). .Awonume mmom 0cm :mEmcflmv mumfimaomoo 0cmumumhxozumal0 Imwflucmncm UHQOUMuH H00 coaumsvw coapmuflumamaomou mo GOHuSHom HMUHSQMHG .HH>X musmflm 52 um. Nb di a d E _ a 4 1 00.0: H ummoumucfl H mm: . NEW-O \HIH QQOHm " HH 9 L_____.n 1:3 (T-J) 0.0 55 III-Reactivity Ratios of Itaconic Anhydride and Styrene 54 A series of eight copolymers of itaconic anhydride and styrene (benzoyl peroxide, initiator), prepared in this laboratory (21), were analyzed by infra-red. A 0.5% solution of polyitaconic anhydride (benzoyl peroxide, initiator), was prepared and diluted with the solvent (acetonitrile) to obtain a series of solutions which were 20%, 40%, 60%, and 80% of the initial concentration. Infra-red spectra of the solutions were obtained, and anhydride peak areas (at 1865 cm-1) were measured. Plotting the measured areas against the per- centage of anhydride, assuming the initial solution to be 100%, a standard curve was constructed. Itaconic anhydride styrene copolymers were dissolved in acetonitrile to form a 0.5% solution, and the infra-red spectra of these solutions were obtained. The peak areas of the itaconic anhydride moieties in the copolymers were measured and from the standard curve the percentages of itaconic anhydride moiety were determined. Mole fraction of itaconic anhydride moiety were calculated from these weight percentages. Infra-red Spectra of different concentration of polyitaconic anhydride are shown in Figure XVIII. Figure XIX shows the standard curve obtained from the spectra and Figures XX and XXI show the infra-red spectra of the series of copolymers. The data from which the reactivity ratios were calculated are given in Table 4. A copolymer composition graph was made by plotting mole fraction of anhydride moiety in the COpolymers (m1) against the initial mole fraction of itaconic 55 anhydride in the reaction mixture (M1) (Figure XXII). Graphical solutions of copolymerization equations by inter- section method and the Fineman and Ross method are shown in Figures XXIII and XXIV, respectively. .mGOHumuuswocoo ucmumMMHU nuHB QOfluSHOm vaflxoumm Hmoucmn cuHB UmuMHuHcHV wUHuvmssm UHcoomuflmaom mo mnuommm UmHIMHHGH .HHH>x 000000 56 ." ‘-‘—~ “- M“ I M 0000 000 Row 100 Itaconic anhydride moiety percent 90r- 80F 70- 60— SOr 40. 20— u— I. ho ! a 3 4 5 6 Peak areas cm2 Hm N Figure XIX. A graph of the areas of anhydride peak at 1865 cm"1 versus the itaconic anhydride moiety percent. 58 .A¢ mHQMB,cH wla musmfiflummxmv muwfihaomou mcmumumlmvflupmzcm Uflcoomuw mo muaommm UwulmnmcH .NX musmflm MK“- l ON Ofi Om om OOfl (%) eouequmSUEIL 59 .A¢ mHQMB CH mum mucmfiflummxm mumfimaomou mammhumlmwfluphncm Uflcoomufl mo muuummm Umutmuch .Hxx musmflm fifiw“ --—_.___ ON ow Om ow f00.“ (%) eoueqarmsuelm 60 .AHNV suoumuoan was» ca rmmnmumrm .z .2 >9 uso pmfiuumo mucmfiflummxm GOHuMNHHmfihaomoo Eoum vwcamuno wum3 mumw mo munmm wmmnem ”$00.0 0.H> m.m m>.0 00.H0 00.0 mmm.0 0.0 00.0H m $00.0 0.00 $.& 005.0 mm.mm 00.0 Hm>.0 0.0 00.0 n m¢m.0 0.00 m.m 0mm.0 Hm.0m mm.¢ mmm.0 5.0 «0.5 m ham.0 m.aw d.m maw.0 mm.>m m.m 0H0.0 0.0 N>.m m >¢m.0 m.0m m.N mmm.0 Nw.mm NN.m 00m.0 ¢.0 m¢.¢ e hmm.0 m.¢m 0.N 0mm.0 mm.0> 0>.m mmw.0 m.0 0m.m m 00m.0 0.Nm >.N 0mm.0 Hm.a> mm.¢ 0m¢.0 N.0 ¢N.N N .m>¢.0 m.m¢ 0.N 00¢.0 00.m> 0¢.N 0mN.0 H.0 NH.H H HE R humfloz .EU .vm MHE unmouwm ucmoumm mEmuw coauomum mfimuo Hmnfisz mUHHUmnad mmud mconumu scam mwamflw 0H0: acme UflcoomuH xmmm mnum>aoo was Iflummxm COHuMNHHmEMHOQOU mcmnhumlmvflnwmncd UflcoomuH How muma OHumm muH>Huumwm .¢ magma Mole fraction of itaconic anhydride moiety in copolymer m1 61 I _. . L..i 0.0 L 4 O 0.1 0.2 0.5 0.4 0.5 0.6 0.7 0.8 0.9 M1 1.0 Mole fraction itaconic anhydride in the reaction mixture Figure XXII. Copolymer composition graph of itaconic anhydride styrene co- polymers. ‘ 62 0.50 is 0,5, 004'? r1 0.2- r1=0.34.i 0.05 r2=0.02 + 0.005 +0.1r r2 Figure XXIII. Graphical solution of copolymerization equation for r1, r2 values in copolymerization of itaconic anhydride-styrene (Intersection method). 63 .Aponumfi mmom paw cmfimsflmv mumfimaomoo wcmumumlmpflupmncm UHcoomuH How coaumsvm COHuMNHHmemaomoo mo coaudaom HMUHLQMHG .>HXN musmflm mm No.0 mm.0 - D I SCUSS ION 64; 65 I - Interpretation of r1, r2 Ratios 66 A. Itaconic Anhydride-Methyl Methacrylate Copolymerization Investigation of the copolymerization of this binary system resulted in r1 = 2.25, r2 = 0.1 (in this work subscript 1 refers to itaconic anhydride). The value of r1 shows that itaconic anhydride radical is about two and one-half times more reactive toward its own monomer than it is toward methyl methacrylate. The r2 value indicates that the reactivity of methyl methacrylate radical toward itaconic anhydride is al- most twenty times greater than that for methyl methacrylate. The product of r1 x r2 is 0.225 which indicates a tendency for the monomer moieties to alternate in the copolymer chain. The copolymerization does not form an azeotrope since one of the ratios (r1) is larger than unity and the other is smaller. To confirm the accuracy of the obtained values, a series of calculations were carried out using available literature data and the Q-e scheme proposed by Alfrey and Price (42). Q and e values for itaconic anhydride are reported to be 2.5 and 0.88 and for methyl methacrylate 0.74 and 0.4, re- spectively (45). Substituting these values in the Alfrey and Price equation: r1 = 92' exp [-ei(ei"ea)] Q _ 2.5 -0.88(0.88540)= r1 — —O.74 e 2.42 (1) r2 = %Z- exp [-e2(e2-e1)] 1 N .5 67 There is some agreement between these calculated r1 and r2 values and the experimental values, but the calculated value of r2 is much larger than that obtained experimentally. This kind of inconsistency is common when only one system is con- sidered,for the Q-e scheme is quite empirical and Q-e values for a monomer, calculated from different systems of co- polymerization vary considerably. To remove this discrepancy and find the factor by which the calculated r1, r2 ratios differ from the experimental ones, a combination of three binary systems are employed when the data is available as follows: r12 = %:_ e—e1(e1-e2) r21 = g:, e’92(e2'el) r23 = 3:. e-e2(e2-e3) (2) r32 = g3, e-es(es'ea) r13 = %:_ e-efiéi'es) r31 = gf, e-es(83‘ei) From these equations, equation (5) follows directly r12r23r31 = r13r32r21 (5) where r12 is the reactivity ratio of the monomer 1 in co- polymerization with monomer 2, and so on. The above relation is often in error and therefore the factor H. has been em— ployed as a correction for values calculated using equation (3). wrr =H (4) r13r32r21 68 Considering three binary systems of methyl methacrylate (1), styrene (2), and itaconic anhydride (5), reactivity ratios for the three systems are as follows: r12 = 0.46 (44) r21 = 0.52 r23 = 0.02 r32 = 0.35 (C) r13 = 0.56 Calculated by means of Q-e scheme r31 = 2.42 therefore, substituting the values in (4) H _ 0.46 x 0.02 x 2.42 _ 0.022264 ‘ 0.36 x 0.55 x 0.52 ” 0.06136 = 0'56 The ratio of calculated values then should differ from the experimental ones by this ratio r (c) _ r EtiTET-x H — Elf-(exp.) 0.129 2.42 0.56 2.42 x 0.56 = which are in agreement with the experimental ratio of g;%§ . B. Itaconic Anhydride-4-Methoxystyrene Copolymerization Reactivity ratio values for this system were calculated by the intersection and by the Fineman and Ross methods. The results were found to be as follows: 69 r1 = 0.52 Intersection Method r2 = 0.03 r; = 0.47 Fineman and Ross Method r2 = 0.05 Since the point of intersection was an area and not a single point, and the author did not have ready access to the mathe- matical evaluation of the point of intersection, by the method of least squares, the values which were obtained from the Fineman and Ross method were considered to be the more reliable. A value of r1 = 0.47 indicates that itaconic anhydride radical is two times more reactive with 4-methoxy- styrene than with itaconic anhydride monomer. The value of r2 = 0.05 indicates that 4-methoxystyrene radical is 55 times more reactive with itaconic anhydride monomer than it is with its own monomer. The product of r1, r2 = 0.014 indicates a high degree of alternation of units in the polymer chain. The composition graph (Figure XVI) shows an azeotrope at a composition M1 = ml = 0.625, where the initial mole fraction of itaconic anhydride in the reaction mixture is equal to the mole fraction of itaconic anhydride moiety in the co- polymer. Calculation of the azeotropic concentrations by means of the copolymerization equation (14) gives a good basis of confirmation for the values obtained in this work. E1. = fl]. rlMl + Ma m2 M2 r2M2 + M1 70 since M1 = m1 and M2 = m2 at azeotrope point rlMl + M2 1 = r2M2 + M1 hence since M1 + M2 = 1 M1 by calculation is found to be 0.645 which differs by only 2% from the azeotropic point obtained. Although this does not prove the validity of the data and the results presented in this work, it is slightly better than the usual results that appear; in the literature when comparisons are made be- tween experimental and calculated azeotropic values obtained by different workers. The approximate reactivity ratios for this system can be predicted from the Alfrey and Price Q-e scheme and are in agreement with the experimental values, if the previously mentioned corrections are applied as follows. Substituting the reported values of Q and e for 4—methoxystyrene, and itaconic anhydride (45): Q_!.. r1 = 02 exp [-ei(ei - e2)] r1 = %:—Z’5>—6— exp [-0.88(0.88 + 1.11)] = 0.515 r2 = %:%§— exp [ 1.11(-1.11-0.88) ]‘=’ 0.06 £1. = 9.-.§1§ r2 0.06 71 The appropriate correction according to Mayo (46) is made by considering the three binary systems of copolymerization of methyl methacrylate (1), 4-methoxystyrene (2) and itaconic anhydride (5). The reactivity ratios of the systems (2,5 and 1,5) are those reported in this work and that of 1,2 by Walling (47). r12 = 0.52 r21 = 0.29 r12 x r23 X rfil = H = 0.52 X 0.06 X 2.25 = O 47 r13 X r21 X r32 0.1 X 0.29 X 0.515 . r23 = 0.06 r32 = 0.51 r13 = 0.10 r31 = 2.25 when the above calculated r1, r2 ratio for the copolymerization of itaconic anhydride with 4-methoxystyrene is multiplied by this factor £2__ 0.06 X 0.47 _ 0.050 r1 ‘ 0.515 ‘ 0.515 This value is in reasonable agreement with the experimental 0.05 0.47 ) found in this work. ratio ( £2-= r1 C. Copolymerization Reactivity Ratios of Itaconic Anhydride and Styrene In the case of itaconic anhydride styrene, the reactivity ratios obtained by the Fineman and Ross method are identical with those obtained by the intersection method. As indicated in Figure XXIII, r1 = 0.54.: 0.05 and r2 = 0.02.i 0.005 were obtained from the method of intersection and as shown in Figure XXIV, values r1 = 0.55 and r2 = 0.02 were obtained 72 from Fineman and Ross method of graphical solution. The value of r1 indicated that itaconic anhydride radical is three times as active toward styrene monomer as it is toward itaconic anhydride monomer. The value of r2 shows the greater re- activity (almost 50 times) of the styrene radical for the un- like monomer. From the fact that the product of rlrg = 0.007, one can readily conclude that the copolymer is highly alternat- ing. The copolymer composition graph (Figure XXII) indicates an azeotrope at 0.59 mole percent itaconic anhydride. Calculation of this point for the itaconic anhydride-styrene system according to Wall, gives a very similar result Ea = _.L___r ‘ 1 M1 r2 " 1 ER : 0'55 - 1 = O 66 M1 0.02 - 1 ° Since M1 + M2 = 1 75 II — General Discussion 74 A. Application of Copplymerization Equations The copolymerization equation as derived, is based on several assumptions (46). One of these is that %%:% represents the relative concentrations of monomers at the site of reaction. This may not be exactly applicable if the poly- mer precipitates as it forms, which is the case in the systems presented in this work. However, it has been found (44) that the monomer reactivity ratios for styrene-methyl methacrylate are the same whether the reaction is carried out in homo- geneous solution or under conditions where the polymer pre- cipitates as formed. On the other hand, Mayo and Walling have reported (48) inconsistencies and irreproducibilities accom- panying the results of the system vinyl acetate -vinyl chloride when the reaction is heterogeneous. The copolymeri- zation equation was used in this work despite the above mentioned inconsistencies, since there was no alternative. B. The Effect of Ring Substitution in the Reactivity of Styrene Type Monomers The reactivity ratios for the copolymerization of the binary system of styrene-4—methoxystyrene have been reported to be r; = 1.16, and r2 = 0.82 (47). This indicates that styrene type radicals tend to react with their own monomer rather than monomeric 4-methoxystyrene, while 4-methoxystyrene type radicals tend to add to styrene molecules rather than 4-methoxystyrene. Therefore a copolymer of styrene with 4—methoxystyrene usually contains more styrene than 4-methoxy- styrene moieties. This was exactly the result found in both 75 the copolymerization of itaconic anhydride with 4-methoxy- styrene and with styrene. Since the styrene radical is more reactive than the 4-methoxystyrene radical more styrene moieties appear in a copolymer of itaconic anhydride and styrene than 4-methoxystyrene moieties in a copolymer of itaconic anhydride and 4-methoxystyrene if the initial molar concentrations of comonomers are equal. The azeotropic values for the two systems are in agreement with this concept. The itaconic anhydride-styrene system forms an azeotrope containing 0.41 mole of styrene, while the itaconic anhydride- 4-methoxystyrene system forms an azeotrope containing about 0.575 mole of 4-methoxystyrene. Axford (49) has investigated the velocity constants in the polymerizations of styrene and 4-methoxystyrene. Comparison of his results indicate that toward a given monomer the radical of the 4—methoxystyrene is less reactive than the styrene radical. The difference in reactivity, he suggested, are due to mesomeric stabilization of the radical with a para substituent. Walling and Mayo (50) have employed the Hammet (1) relationship log £0 = 6 p (1) to explain the effect of substituents on the styrene molecule. In the above equation k and k0 are rate constants for the reaction of the side chain of the substituted and unsubstituted benzene, 0 is a parameter for each substituent and p is a parameter depending only upon the reaction (here free radical reaction). Walling and Mayo applied this to copolymerization 76 of styrene with various substituted styrenes. They plotted the logarithms of relative reactivities of substituted styrene against the Hammett 0 values for the substituents. They found that the system obeyed equation (1) quite exactly. They also calculated the slope of the curve and found p to be 0.51. This indicates that the more active electron donor substituent is, the lower the reactivity at the site of the reaction becomes. The results obtained in this work seem to indicate that itaconic anhydride radical, which is less stabilized by resonance, is more reactive than the styrene radical and therefore enters the copolymer more readily. By the same token itaconic anhydride has an even higher reactivity in the case of its copolymerization with 4-methoxystyrene. This phenomenon does not correlate with the general thermodynamic concept of the formation of more stable radicals. Walling and Mayo (50) have approached this problem by employing electron accepting and donating proper- ties of a conjugated carbonyl system and an aromatic ring system. They considered a transition state in which an electron had been donated from the double bond of styrene or the substituted styrene to the conjugated carbonyl radical. In the case of itaconic anhydride the structure of the tran- sition state may be illustrated as: * + CH-CHg l e \ '° /. CH2—-q§ K _\ 0/ 77 The resulting structure for itaconic anhydride will be an enolate ion which is relatively stable. This also may account for increased reactivity of the electron donor substituted styrene toward conjugated carbonyl radicals, since the substituted styrene ion radical has a number of additional structures. A similar approach has been taken by Bartlett and Nozaki in the copolymerization of maleic an- hydride and allyl acetate (51). Walling and Mayo furthermore have suggested that the attack of the styrene radical on conjugated carbonyl monomers often results in a thermo- dynamically stable transition state. This transition state may be an addition complex of the monomer which then forms a complex radical that participates in the copolymerization. They proved the formation of such addition complexes by spectroscopy in the ultra violet region of the spectrum. In this laboratory the formation of complexes from maleic anhydride and para substituted styrenes has been investi- gated (52). Following the above discussion one could con- clude that the cause of differences in reactivities of styrene and 4-methoxystyrene might be the result of some type of complex or adduct formation. A 1:1 adduct which polymerizes might also account for the alternating copolymer. C. Infra—red Quantitative Analysis This quantitative method of analysis proved to be con~ venient, simple and accurate for all systems studied. It was very useful for the itaconic anhydride-methyl methacrylate 78 system, since the carbon contents of the two monomer units were so close that elemental analysis could not be employed. In the case of the itaconic anhydride-4-methoxystyrene system, a model compound was used. The model compound, p-sec. butyl anisole gave the anticipated absorbances of polymethoxy- styrene in the area of interest (at 1865 cm-l). This is probably due to the styrene moiety in the copolymer having a similar structure in respect to the attachment of groups at the carbon d,to the phenyl ring. A series of experiments in the infra—analysis of copolymers of polyvinylacetate with itaconic anhydride have been carried out in this laboratory using sec-butyl acetate as a model for the polyvinyl acetate (55). Infra-red analysis and elemental analysis for a series of copolymers of itaconic anhydride with 4—methoxystyrene gave comparable results (see Table 5). Since polystyrene was insoluble in the solvent (acetonitrile) which dissolves poly- itaconic anhydride and no suitable common solvent useful in infra-red analysis could be found, it was decided to carry out the analysis of samples by means of a calibration curve constructed by measurement of anhydride peak areas of only polyitaconic anhydride solution at different concentrations. This might have been inaccurate if polystyrene or styrene moieties in the copolymer had had an absorbance in the same region as the anhydride. However, it is known that the only possible absorbances of polystyrene are very weak summation bands (overtones and combinations) of the C—H out of plane 79 deformation frequencies in the range of 2000-1650 cm“1 (506.06 0). When the solutions used are dilute (in this work 0.5%), these bands are negligible. Calculation of compo- sition of the series of the itaconic anhydride-styrene copolymers based on a calibration curve drawn by plotting the areas of anhydride peaks of standard solutions vs their anhydride content, gave results in agreement with those ob— tained by elemental analysis (Table 4). SUMMARY 80 81 1. Binary copolymerizations of itaconic anhydride with six comonomers (vinyl pyrrolidine, 4—methoxystyrene, 2-chlorostyrene, 5-chlorostyrene, styrene, and divinyl ether) were carried out in tetrahydrofuran using 2,2'-azodiiso- butyronitrile as an initiator. 2. The reaction parameters were determined for the co- polymerization of itaconic anhydride Ml with methyl methacry- late M2 in benzene. 5. The reaction parameters were determined for the co- polymerization of itaconic anhydride M; with 4-methoxystyrene M2 in benzene. 4. Quantitative infra-red analysis has been used to determine the anhydride moiety and thus copolymer composition of samples of itaconic anhydride co styrene, itaconic an- hydride co 4-methoxystyrene and itaconic anhydride co methyl methacrylate. 5. It has been demonstrated that a model compound can be used in place of the non-anhydride containing homopolymer to construct reference graphs useful for analysis of the compo- sition of itaconic anhydride copolymers. 6. It has been demonstrated that polyitaconic anhydride can be used to construct reference graphs useful for analysis of the composition of itaconic anhydride copolymers if there -1 is no interference in the anhydride peak region at 1865 cm by the comonomer unit. 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