Copolymers of poly(styrene‐co‐4‐bromostyrene) (PBrxS) with adjustable monomer sequence distribution of styrene (S) and 4‐bromostyrene (4‐BrS) and composition (x = content of 4‐BrS) are prepared by brominating parent polystyrene (PS). While bromination reaction carried out above the theta temperature (Θ) leads to PBrxS with random monomer distribution, bromination of PS performed at temperatures below Θ produces PBrxS having a random‐blocky character.
We study the effect of comonomer sequence distributions in random copolymers (RCPs) on RCP adsorption on flat impenetrable surfaces. RCP poly(styrene-co-4-bromostyrene) (PBr x S), where x denotes the mole fraction of 4-bromostryrene (4-BrS), is prepared by bromination of parent homopolystyrene. By varying the solvent quality during the bromination, either "truly random" (good solvent) or "random-blocky" (poor solvent) PBr x S RCPs are prepared. Adsorption studies of PBr x S from various solvents at silica surfaces reveal that the adsorption of PBr x S increases with (1) increasing blockiness of the macromolecule, (2) increasing content of 4-BrS in PBr x S, and (3) decreasing solvent quality. Additionally, the effect of comonomer sequence distribution on RCP adsorption is modeled in detail using a coarse-grained statistical mechanical model and fully atomistic simulations based on configurational-biased grand-canonical Monte Carlo (CB-GCMC) technique. The main result from the simulations can be summarized as follows: (1) Increasing the degree of "blockiness" in comonomer distribution enhances the adsorption of macromolecules dissolved in a good solvent. (2) Near the adsorption transition, the amount of adsorbed segments in "random-blocky" copolymers is larger relative to their regular multiblock counterparts. (3) Lowering the solvent quality facilitates copolymer adsorption. Overall, the findings from computer modeling are found to be in a good agreement with the experimental data.
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