Exploration For Decreasing Volume Shrinkage In Photopolymerization

Photopolymerization consist of two mechanisms which are freeradical polymerization and cationic polymerization. There are inherentinsufficient for both mechanism, for the free radical mechanism, whichmonomer is very volatile, oxygen resistance is strong and thepolymerization shrinkage effect is high. Especially the volume shrinkagehas always been an important problem to be solved, because thephotopolymerization process can change the distance of van der waalsforce into the distance of covalent bond between the monomers oroligomers. Which lead to poor adhesion stress and high internal stress,make its application is very limited.This article explored one method to decrease the volume shrinkagefor photopolymerization including synthesis of a series ofmethacrylate-vinyl ether hybrid monomer, combination initiator systemand introduction of chain transfer agent. Its photopolymerization kineticswas monitored by Fourier transform real-time infrared spectroscopy(FTIR) and the volume shrinkage is measured by using laserdisplacement sensor (LDS), the adhesion strength is also evaluated. The results indicated that the chain segment structure and the conversion oftwo different double bonds play an important role in volume shrinkage ofphotopolymerization. The volume shrinkage could be adjusted in somedegree on demand which is good for adhesion strength. We can get lowervolume shrinkage while the conversion is good, it is envisioned that thiscomprehensive solution could initiate universal application in highresolution and strong adhesion strength UV-curing system.