Polymerization-Induced Microphase Separation with Long-Range Order in Melts of Gradient Copolymers.

Alexey A Gavrilov,Alexander V Chertovich

doi:10.3390/polym12112637

Abstract

In this work, we studied the question of whether it is possible to develop a one-step approach for the creation of microphase-separated materials with long-range order with the help of spontaneous gradient copolymers, i.e., formed during controlled copolymerization solely due to the large difference in the reactivity ratios. To that end, we studied the polymerization-induced microphase separation in bulk on the example of a monomer pair with realistic parameters based on styrene (S) and vinylpirrolydone (VP) by means of computer simulation. We showed that for experimentally reasonable chain lengths, the structures with long-range order start to appear at the conversion degree as low as 76%; a full phase diagram in coordinates (fraction of VP—conversion degree) was constructed. Rather rich phase behavior was obtained; moreover, at some VP fractions, order–order transitions were observed. Finally, we studied how the conversion degree at which the order–disorder transition occurs changes upon varying the maximum average chain length in the system.

Highlights

Gradient copolymers are a special class of macromolecules in which the chain composition smoothly changes along the chain [1,2]
The results obtained from the dissipative particle dynamics (DPD) simulations at χ = 0 and kinetic model (KM) are in good agreement; the differences observed in the transition region are most probably related to the chain polydispersity (even though the obtained dispersity value Ð of 1.012–1.013 is rather small, see the graphical chain representations in Figure 1) as well as the simplified growth process in the KM where all the Polymers 2020, 12, x FOR PEER REVIEW
Summarizing, in this work we studied polymerization‐induced microphase separation in melts of copolymers formed by model monomers based on styrene and vinylpyrrolidone by means of computer simulations

Summary

Introduction

Gradient copolymers are a special class of macromolecules in which the chain composition smoothly changes along the chain [1,2]. Spontaneous gradient copolymers are produced spontaneously due to the feed composition drift that occurs naturally during the reaction From this circumstance, the main requirement for the synthesis of such gradient copolymers arises; in order to achieve a significant change in the monomer composition along the polymer chains, the difference in reactivity ratios (r1 and r2 ) must be rather substantial. The main requirement for the synthesis of such gradient copolymers arises; in order to achieve a significant change in the monomer composition along the polymer chains, the difference in reactivity ratios (r1 and r2 ) must be rather substantial Both these approaches have their own advantages and disadvantages; while the former one has much

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Results

Conclusion