Synthesis of polymer networks by means of addition reactions of tri-amine and poly(ethylene glycol) diacrylate or diglycidyl ether compounds

Polymer networks have been synthesized by addition reactions of tri-functional amine, tris(2-aminoethyl)amine (TAEA) or trimethylolpropane tris[poly(propylene glycol)amine terminated] ether (PPGTA), and poly(ethylene glycol) diacrylate (PEGDA), or poly(ethylene glycol) diglycidyl ether (PEGDE) in dimethyl sulfoxide (DMSO) as a solvent. These reactions yielded the gels in which the polymer networks were homogeneously swollen in DMSO. An increase in the monomer concentration increased Young’s modulus and breaking stress of the gels. The gels with PPGTA showed flexible features in comparison with those with TAEA due to the flexible molecular structure of PPGTA. The gels composed of TAEA and PEGDA or PEGDE with high molecular weight tended to show lower Young’s modulus and higher breaking strain than the gels composed of those with low molecular weight due to the decrease in the cross-linking density and/or increase in flexibility of the PEG unit accompanied by the increase in the molecular weight of PEG. The gels with PPGTA showed opposite tendency, indicating entanglement of PEG unit with high molecular weight, which would play a role of physical cross-linking points in the gels. The gels prepared in N,N-dimethylformamide (DMF) were flexible in comparison with the gels prepared in DMSO due to the high miscibility of the network and DMF. The reaction systems of TAEA and PEGDA with low molecular weight in ethanol formed porous polymeric networks derived from the phase separation during the polymerization. The porous polymeric networks were unbreakable by compression and absorbed various organic solvents.