Effect of Comonomer Sequence Distribution on the Adsorption of Random Copolymers onto Impenetrable Flat Surfaces

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• 作者：Young K. Jhon^† ; ; James J. Semler^† ; ^# ; Jan Genzer*^† ; ; Martin Beevers^225 ; ; Olga A. Gus’ ; kova^§ ; ; Pavel G. Khala
• 刊名：Macromolecules
• 出版年：2009
• 出版时间：April 14, 2009
• 年：2009
• 卷：42
• 期：7
• 页码：2843-2853
• 全文大小：480K
• 年卷期：v.42,no.7(April 14, 2009)
• ISSN：1520-5835

文摘

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_xS), 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_xS RCPs are prepared. Adsorption studies of PBr_xS from various solvents at silica surfaces reveal that the adsorption of PBr_xS increases with (1) increasing blockiness of the macromolecule, (2) increasing content of 4-BrS in PBr_xS, 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.