We have studied the influence of segmental dipole orientation on the solution properties of polyzwitterions using dynamic and static light scattering of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), n-butyl-substituted choline phosphate polymers (PMBP), and their diblock (PMPC-b-PMBP) copolymers in solutions of different salt concentration. We find that these three structures exhibit dramatically different aggregation behaviors. For the conditions in our study, PMPC is a swollen excluded-volume chain without significant presence of dipolar correlations as evident from the lack of sensitivity to the ionic strength of the solution. In contrast, PMBP self-assembles into finite-sized structures in solution, which are stabilized by electrostatic dipole-dipole interactions. Evidence of these interactions is also present in the diblock polymer, PMPB-b-PMPC, which self-assembles into two distinct, stable aggregates in addition to unaggregated chains. These results contribute to the breadth of understanding of polyzwitterions in solution and provide a platform for future simulation and experimental explorations.
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© 2016 American Chemical Society.