Synthesis and properties of degradable gels and porous polymers including acetal group in the network structure by addition reaction of multi-functional phenols and divinyl ether compounds

Gels containing acetal group have been synthesized by addition reaction of multi-functional phenols, 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) or tannic acid (TA) and divinylethers, diethylene glycol divinyl ether (DEGVE) or polyethylene glycol divinyl ether (PEGVE) in tetrahydrofuran (THF) or 1,4-dioxane (DO) using pyridinium p-toluenesulfonate as a catalyst under nitrogen atmosphere.The gels synthesized from DEGVE showed higher Young’s modulus, breaking stress, and lower breaking strain than the gels synthesized from PEGVE. The gels in DO showed higher mechanical properties than those in THF due to the high affinity between the network structure and the solvent used. The gels with TA showed lower Young’s modulus than those with THPE derived from flexible molecular structure of TA. The reaction of THPE and PEGVE in acetonitrile induced phase separation, and yielded porous polymer formed by connected globules about 10 μm diameter. The dried porous polymers showed remarkable increase in the Young’s modulus in comparison with the corresponding gels in THF or DO. The gels and porous polymers were degraded under atmospheric conditions caused by hydrolytic degradation of acetal groups in the network structure. The present hydrolytic degradable materials would be applicable for drug carriers or sensors for humidity or water.