Synthesis and mechanical properties of IPN gels synthesized by addition reaction between multifunctional and bifunctional compounds combined with ring-opening polymerization of multifunctional-epoxides

Interpenetrating polymer network (IPN) gels have been synthesized by combination of networks formed by thiol-ene reaction of multifunctional compounds with bifunctional compounds (1st network) and ring opening polymerization of poly(ethylene glycol) diglycidylether (PEGDE) (2nd network). The 1st network was formed by thiol-ene click reaction of a multi-functional vinyl siloxane, (1,3,5,7-tetramethylcyclotetrasiloxane, TVMCTS) and an alkyl dithiol, (1,10-decane dithiol, DDT) in toluene. The mechanical properties of the IPN gels were investigated by compression tests. The IPN gels showed a higher breaking stress and breaking point than the single network gel. The 1st network has been also synthesized by the thiol-ene reaction of multi-functional thiol compounds and poly(ethylene glycol) diacrylate in some organic solvents (toluene, tetrahydrofuran). These IPN gels also showed higher breaking stress and breaking point in comparison with the corresponding single network gels. The IPN gels with PTMB showed higher Young's modulus due to the physical entanglement between the 1st and 2nd networks. The reaction system of caster oil-hexamethylene diisocyanate (HDI)/epoxized soybean oil (ESO) was also usable to synthesize IPN gels. The 1st and 2nd networks were formed by the addition reaction of caster oil and HDI, and ring opening polymerization of ESO, respectively. The composition ratio and formation order of the 1st and 2nd network affected the mechanical properties of the resulting IPN gels. 2019, The Society of Polymer Science, Japan.