Conformational transition of telechelic star polymers

Abstract

We report dynamic Monte Carlo (DMC) simulation study of solution behavior of multi-arm telechelic star polymers, wherein the number of branching (f) increases with decreasing arm length (n); thus keeping the total number of monomer (N) in the molecule around a constant value. On deteriorating solvent quality, the conformational change occurs from an open to a compact globule structure. The terminal functional groups form aggregate as the solution is cooled progressively and the aggregation phenomenon drives the collapse transition. The transition temperature follows a non-monotonic trend with the functionality, in comparison with an equivalent series of star homopolymers. The non-monotonic behavior of telechelic star polymer is attributed to the interplay between enthalpic gain due to end-monomer aggregation and entropic loss due to loop formation. Structural analysis reveals that, aggregation of end group yields a structure resembles to “watermelons” (WM). Simulation results for the systems with varying N (keeping f or n constant and varying n or f) shows the similar mechanism to the constant N system. Further, we discuss results on highly branched telechelic star polymer with shorter arm length, where, we observe the formation of collapsed structures with single and double aggregates in isothermal and non-isothermal cooling respectively.