Gradient copolymers with well-defined architectures are increasingly desired in a wide range of applications ranging from compatibilizers for polymer blends to materials for biomedical applications. Although there are many studies investigating the physical and mechanical properties of gradient copolymers, the explicit sequence along the copolymer chains is unknown, and the existence of a gradient is inferred from overall composition measurements. NU-MRSEC researchers have developed a general computational framework based on kinetic Monte Carlo simulations to predict the explicit sequence of copolymers. The researchers demonstrate the approach using styrene/methyl methacrylate gradient copolymers and show that the variation in the average sequence length as a function of chain length does not resemble that of the instantaneous composition, which has been considered to be sufficient to characterize gradient copolymers. The findings indicate that copolymers with compositional gradients may have chain topologies resembling those of statistical copolymers and suggest that characterization of “structural” gradients is warranted.
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