Interpenetrating Polymer Networks (IPNs) are materials containing two or more components that have been polymerized and crosslinked in the presence of each other to form entangled (interpenetrated) networks. The morphology of such crosslinked entanglements of two, or more, diverse immiscible polymeric networks can lead to interesting physical properties due to development of single-phase morphology at the macro scale. Currently, products derived from IPNs find applications ranging from to ion-exchange resins, adhesives, high impact plastics, thermoplastics, vibration-damping materials (for outdoor, aircraft and machinery applications), high temperature alloys and medical devices. Siloxane polymer systems in IPNs with rigid materials such as polyacrylates or polystyrene provide high flexibility, water vapor permeability and biocompatibility. This thesis reports on studies, of newly engineered biobased IPN systems based on soybean oil and polysiloxanes. Soybean oil is a triglyceride molecule containing on average 4.6 double bonds per mole. Reaction with vinyltrimethoxy silane through "ene" chemistry provides silylated soybean oil. Silylation of oligomerized soybean oil provides a more viscous, higher molecular weight polymer system for IPN formation. The second component in these IPNs was either a silanol terminated polydimethylsiloxane (PDMS) or carbinol containing hydrophilic polysiloxanes. High molecular weight PDMS was prepared by emulsion polymerization of silanol terminated silicone oligomers. Carbinol containing hydrophilic polysiloxanes were prepared by polymerization of 3-aminopropylmethyldiethoxysilane followed by a reaction with cyclic carbonate. These hydrophilic polysiloxanes were water-soluble independent of the water pH or their molecular weight and were characterized by high degree of hydrogen bonding. A series of IPNs were prepared containing different concentrations of silylated soybean oil and silicone polymers. Different processing options were studied in the production of the IPNs. These include IPNs prepared by the latex method and IPNs prepared by a solution method. In both cases evaporation of the water or the solvent led to stable siloxane crosslinks. Another process involved IPNs prepared by dissolving the water soluble polysiloxanes in the water phase that was used to emulsify the silylated soybean oil. In these IPNs, evaporation of the water phase led to crosslinked films containing stable siloxane (Si-O-Si) linkages as well as hydrolytically less stable siloxy (Si-O-C) linkages.Control of the siloxanes crosslinks provides control of morphology and prevents gross phase separation of the soybean and silicone phase. A model, based on Donatelli's equation was constructed to determine the crosslink density of these networks which was then correlated with the physical properties of these IPNs. Various processes and compositions were studied to assess the potential use of these IPNs in coating applications. The morphology of cast films from each of these IPNs revealed an intimate mixing of the two immiscible components with no apparent gross phase separation. The crosslink density, mechanical properties, thermal properties and surface properties of all IPNs were investigated and correlated with their composition. These IPNs can be utilized as high release liners, low friction materials or as general protective coatings. The combination of natural product with polysiloxanes makes these IPNs suitable for various applications in cosmetics and personal care. IPNs containing hydrolytically susceptible siloxy crosslinks can be utilized to prepare environmentally degradable materials that can be used in various control release applications.
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