Abstract: By the ring-opening polymerization of caprolactone, PCL-b-PDMS-b-PCL triblock amphiphilic polymer was obtained and added into the cyanate ester thermosetting resin, producing a mixture of self-assembled nanostructures. In the ester resin prepolymer, a cyanate resin/block modification mixture having a nanocomposite structure is obtained. The results of cyanate resin/block system SAXS and TEM confirm that the 50 nm~60 nm nanostructures were achieved by CE/PCL-b-PDMS-b-PCL system. The system also has a diverse morphology from particles to worm-like structures as the block polymer content increases. Meanwhile, the average distance between neighboring microdomains increases. The mechanism of the the CE/PCL-PDMS-PCL is self-assembling. By non-isothermal DSC curing and critical stress intensity factor (K_IC) value, the block-modified resin is 25 ℃~50 ℃ ahead of the exothermic peak of the unmodified CE resin, indicating that the reactivity of blends system is improved. The K_IC of the 20 wt% block content of CE/PCL-b-PDMS-b-PCL was 0.65, which was 97% higher than that of the unmodified CE system, demonstrating that the fracture toughness of the block-modified resin is improved.

Key words: block copolymer, cyanate resin, self-assembly