This article describes the photoinitiated cationic copolymerization of 1

6

8

13-tetraoxaspiro [7

7] tridecanes (SOC7)

unconstrictive monomer

and 3

4-epoxycyclohexylmethyl 3

4-epoxycyc-lohexane carboxylate (ERL-4221). The test results show that the addtion of a small amount of SOC7 to ERL-4221 system results in suppressing shrinkage without significantly degrading the thermal properties. The proper mol ratio of ERL-4221 to SOC7 is 4:1. A crosslinked copoly-mer having Tg 230℃ and volume shrinkage below 4.4% on photocopolymerization is obtained. The elemental analysis

FT-IR and 1H-NMR spectra were shown respectively for characteri-zation of the photocopolymer.