Reaction-induced microphase separation

Block copolymers have long been applied to modify thermosets, since the first reports made by Bates [78]. The rheology of the order-disorder transition of diblock copolymers in epoxy monomers was first studied by Fine et al. [79], who suggested that a solid-like to a liquid-like transition would correspond to such a structural transition due to the solubility changes that occur around the transition. Subsequently, Serrano et al. [80] examined the rheological behavior of an epoxi-dized styrene-butadiene linear diblock copolymer-modified epoxy with nanostructures. An increase in the magnitude of both the viscosity and the moduli was detected for the block copolymer-modified blends just before gelation, associated with the reaction-induced microphase separation (RIPS). 

Polyimide containing poly(ethylene oxide) is a simple and convenient way to improve the gas separation properties. The copolymers are synthesized by the reaction of dianhydride and diamines with/without amine-terminated poly(ethylene oxide). Maya el al. and Munoz et al. reported thermal treatment effect of PEO-Z)-PI copolymer on the gas permeation properties. Phase segregation of the polymer chain at higher treatment temperature to 300 °C contributed to improvement of gas permeability of the membrane. Molecular weight of poly(ethylene oxide) of 6000 was appropriate to induce microphase separation. CO2 permeability was reached from 2.3 to 24 Barrer according to the PEO composition before thermal treatment, while it was enhanced by three to ten times higher permeability after thermal treatment at 300 °C without serious reduction in permselectivity. 

---