Reactive comb (RC) polymers were synthesized by copolymerizing methyl methacrylate (MMA) with glycidyl methacrylate (GMA) and a kind of MMA macromer. The obtained molecules had both epoxide groups and long PMMA side chains distributed randomly along the PMMA backbone. The synthesized RC polymers were applied as compatibilizers in an immiscible poly(L-lactic acid)/poly(vinylidene fluoride) (PLLA/PVDF) system. Compared to their linear counterparts, only 1 wt% of RC polymers with appropriate length of side chains significantly reduced the size and enhanced the uniformity of the PVDF dispersed phase in PLLA matrix and the RC-compatibilized blends exhibited a significant improvement in fracture strain. The higher compatibilization efficiency of RC polymers was ascribed to the existence of PMMA side chains, which improved the stability of RC polymers at the interface of immiscible blend and this was demonstrated by TEM.

A reactive comb (RC) polymer, which was composed of one poly(methyl methacrylate) (PMMA) backbone, two PMMA side chains and a few epoxy groups that distributed randomly along the backbone, was applied as a compatibilizer in an immiscible poly(L-lactic acid)/acrylonitrilebutadiene-styrene) system (PLLA/ABS). The morphological structures, the rheological, mechanical and thermal properties of the obtained PLLA/ABS blends were investigated systematically. For the first time in the reactive compatibilized system, we found that the glass transition temperature (T g ) of both PLLA and ABS phase depressed to lower temperature and the toughness of the compatibilized PLLA/ABS blend was significantly improved. The effect of blending composition showed that both the depression of T g and the improvement of toughness were most significant at the weight ratio of 50/50, at which the area of PLLA/ABS interface was the largest. It is considered that the in-situ formed PLLA grafted RC polymers at the PLLA/ABS interface drastically improved the interfacial adhesion between the two phases. Thus the internal pressure, derived from the differentiation of the thermal contraction between the PLLA and ABS phase during cooling from the melt, significantly enhanced the mobility of the molecular chains of the both components on a microscopic scale, which was manifested by a double T g depression phenomenon on a macroscopic scale. This investigation revealed that both the interfacial adhesion and asymmetric thermal shrinkage are important for the toughening of a rigid/rigid polymer blend.

Reactive comb (RC) polymers with different molecular architectures have been successfully synthesized by copolymerizing methyl methacrylate (MMA), glycidyl methacrylate (GMA), and a series of MMA macromer with different molecular weights. The prepared RC polymers with different lengths of side chains were applied as compatibilizers in an immiscible poly(L-lactic acid)/poly(vinylidene fluoride) (PLLA/PVDF) blend, and it was found that the RC polymers with moderate length of side chain (e.g., M n = 4800 g mol −1 ) displayed better compatibilizing efficiencies than RC polymers with short side chain (e.g., M n = 2400 g mol −1 ) and let alone the reactive linear (RL) polymers without side chains. The thus obtained PLLA/PVDF blends with PLLA as a matrix will provide excellent adhesion with the surfaces of the metals and cells, and it was found that RC polymers endowed the PLLA/ PVDF blend with excellent toughness and the RC-compatibilized blend could be uniaxially stretched to a maximum draw ratio of 5 at room temperature (about 22 °C). FT-IR and XRD results showed that the nonpolar α phase of PVDF was completely transformed into the piezoelectric β phase (more than 95%) during the stretching.

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