Effect of thermal oxidation on the self-assembly of triblock terpolymers

This paper reports an investigation of the thermal degradation of a poly(styrene-b-butadiene-b-methyl methacrylate) triblock terpolymer compared with those of butadiene rubbers and poly(styrene-b-methyl methacrylate). According to sol-gel properties changes, it was proposed that polybutadiene blocks undergo mainly crosslinking. However, these latter coexist with chain scissions occurring in polybutadiene blocks, which generates poly(butadiene-b-methyl methacrylate) and poly(butadiene-b-styrene) diblock chains, and possibly chain scissions occurring in polystyrene and poly(methyl methacylate) blocks. The consequences of the degradation on the self-assembly of triblock terpolymer were studied through the annealing kinetics monitored by Atomic Force Microscopy. It appears that at low conversion degrees, chain scissions induce a faster self-assembly kinetics. At higher oxidation degrees, crosslinking of butadiene phase combined with scissions induces a “frozen” state at high annealing times characterized by a macrophase separation.