Monte Carlo simulations of crystallization in heterogeneous copolymers: The role of copolymer fractions with intermediate comonomer content

Heterogeneous copolymers contain diverse comonomer contents among copolymers, and the extremely diverse case becomes a binary polymer blend. We report a numerical study of crystallization in two series of heterogeneous copolymers that are separated with strong and weak heterogeneities of comonomer distributions, and both of which are composed of crystallizable monomers and noncrystallizable comonomers with various compositions. A comparison of simulation results between these two series of samples demonstrates that, something like a compatibilizer in an incompatible polymer blend, copolymer fractions with intermediate comonomer contents between two compositional extremities depress the prior liquid-liquid demixing on cooling, and hence weaken the subsequent crystallization behaviors. However, we found that in these intermediate fractions, comonomers distribute quite homogeneously on each chain and the amphiphilicity occurs on multiple short sequences, rather than like on a diblock copolymer.