Kiff F Thomas, Richards Randal W, Thompson Richard L
Department of Chemistry, University of Durham, South Road, Durham DH1 3LE, U.K.
Langmuir. 2004 May 25;20(11):4465-70. doi: 10.1021/la035825b.
The effectiveness of a "solvent annealing" process was investigated for thin (approximately 150 nm) polystyrene films, in which the diffusion and reorganization of polymer chains were mediated by the controlled absorption of cyclohexane vapor. Results were compared with conventional "thermal annealing" of films under vacuum above the glass transition temperature. Elastic recoil detection analysis (ERDA) was used to determine the surface excesses of fluorocarbon end-capped polystyrene (hPSF) and poly(styrene-b-dimethylsiloxane) (hPS-PDMS) in deuterated polystyrene (dPS) films. Both annealing methods enabled diffusion of the surface-active polymers; however, only thermal annealing gave rise to a surface excess in hPSF/dPS films. The inhibition ofhPSF adsorption under solvent annealing was due to the low surface tension of cyclohexane. In contrast, hPS-PDMS, having a larger surface-active group than that of hPSF, was found in excess at the air surface under solvent annealing, and surface excesses were consistent with the formation of saturated monolayers in blended films. The mixing of hPS-PDMS with dPS was inhibited by the unfavorable interaction between the PDMS block of the copolymer and the homopolymer. The slow interdiffusion of hPS-PDMS in dPS is consistent with the formation of micelles, and the formation of an excess layer at the air surface may be kinetically inhibited by the rate of dissociation of hPS-PDMS micelles.
研究了“溶剂退火”工艺对约150纳米厚的聚苯乙烯薄膜的有效性，其中聚合物链的扩散和重组是由环己烷蒸汽的受控吸收介导的。将结果与在高于玻璃化转变温度的真空下对薄膜进行的传统“热退火”进行了比较。采用弹性反冲探测分析（ERDA）来测定氘代聚苯乙烯（dPS）薄膜中氟碳封端聚苯乙烯（hPSF）和聚（苯乙烯-b-二甲基硅氧烷）（hPS-PDMS）的表面过量。两种退火方法都能使表面活性聚合物扩散；然而，只有热退火能使hPSF/dPS薄膜产生表面过量。溶剂退火下hPSF吸附的抑制是由于环己烷的低表面张力。相比之下，具有比hPSF更大表面活性基团的hPS-PDMS在溶剂退火下在空气表面过量存在，并且表面过量与共混薄膜中饱和单分子层的形成一致。hPS-PDMS与dPS的混合受到共聚物的PDMS嵌段与均聚物之间不利相互作用的抑制。hPS-PDMS在dPS中的缓慢互扩散与胶束的形成一致，并且空气表面过量层的形成可能在动力学上受到hPS-PDMS胶束解离速率的抑制。
