Effect of Comonomer Sequence Distribution on the Adsorption of Random Copolymers onto Impenetrable Flat Surfaces
Effect of Comonomer Sequence Distribution on the Adsorption of Random Copolymers onto Impenetrable Flat Surfaces
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DOI：
10.1021/ma8027936
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发表时间：
2009-04-14
期刊：
影响因子：
5.5
通讯作者：
Khokhlov, Alexei R.
中科院分区：
文献类型：
--
作者：
Jhon, Young K.;Semler, James J.;Khokhlov, Alexei R.
研究了无规共聚物中共聚单体序列分布对RCP在平坦不可穿透表面上吸附的影响。以均聚苯乙烯为原料，通过溴化反应制备了4-溴苯乙烯（4-BrS）-苯乙烯共聚物（PBrxS）。通过在溴化过程中改变溶剂质量，可以制备“真正无规”（良溶剂）或“无规嵌段”（不良溶剂）的PBrxS RCP。对不同溶剂中PBrxS在SiO2表面的吸附研究表明，随着分子嵌段度的增加、4-BrS含量的增加和溶剂质量的降低，PBrxS在SiO2表面的吸附量增加。此外，共聚单体序列分布对RCP吸附的影响进行了详细建模，使用粗粒度的统计力学模型和完全原子模拟的基础上配置偏置的巨正则蒙特卡罗（CB-GCMC）技术。模拟的主要结果可以概括如下：（1）增加共聚单体分布中的“嵌段”程度增强了溶解在良溶剂中的大分子的吸附。(2)在吸附转变附近，“无规嵌段”共聚物中的吸附链段的量相对于它们的规则多嵌段对应物较大。(3)降低溶剂质量有利于共聚物吸附。总体而言，从计算机建模的结果被发现是在一个很好的协议与实验数据。
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) (PBrxS), 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) PBrxS RCPs are prepared. Adsorption studies of PBrxS from various solvents at silica surfaces reveal that the adsorption of PBrxS increases with (1) increasing blockiness of the macromolecule, (2) increasing content of 4-BrS in PBrxS 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.