Surface-initiated anionic polymerization of styrene by means of self-assembled monolayers
Surface-initiated anionic polymerization of styrene by means of self-assembled monolayers
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DOI：
10.1021/ja981348l
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发表时间：
1999-02-10
影响因子：
15
通讯作者：
Sokolov, J
中科院分区：
文献类型：
--
作者：
Jordan, R;Ulman, A;Sokolov, J
描述了在平面上制备致密聚合物刷的合成概念，其中金基底上联苯锂部分的自组装单层（SAM）用于引发苯乙烯的阴离子聚合。通过椭圆光度法和原子力显微镜 (AFM) 估计，所得干聚苯乙烯刷的厚度为 18 +/- 0.2 nm。这些技术还揭示了整个基材在宏观和微观尺度上的光滑、均匀的聚合物表面，粗糙度为 0.3-0.5 nm (rms)。根据椭圆光度法监测的原位溶胀实验结果，使用平均场理论计算出 N = 382 的聚合度和约 7-8 条链/R-g(2) 或 3.2-3.6 nm(2)/链的接枝密度。接枝层的偏振外反射 (ER) FTIR 光谱证实了高度拉伸的优先取向聚苯乙烯链。退火后，旋涂聚苯乙烯薄膜立即使刷表面脱湿，形成接触角为 3 度的聚合物液滴。所有获得的结果表明，所描述的合成方法产生了密集接枝的聚合物刷，其实验研究到目前为止还非常有限。
A synthetic concept of preparing dense polymer brushes on planar surfaces is described, in which a self-assembled monolayer (SAM) of biphenyllithium moieties on gold substrates is used to initiate anionic polymerization of styrene. The thickness of the resulting dry polystyrene brush, as estimated by ellipsometry and atomic force microscopy (AFM), is 18 +/- 0.2 nm. These techniques also reveal a smooth, homogeneous polymer surface throughout the entire substrate on the macroscopic, as well as on the microscopic, scale, with a roughness of 0.3-0.5 nm (rms). On the basis of results from in situ swelling experiments, monitored by ellipsometry, a polymerization degree of N = 382 and a grafting density of approximately 7-8 chains/R-g(2), or 3.2-3.6 nm(2)/chain, were calculated with use of mean-field theory. Polarized external reflection (ER) FTIR spectra of the grafted layer confirm highly stretched preferentially oriented polystyrene chains. Upon annealing, spin-coated polystyrene films dewet immediately the brush surface to give polymer droplets with a contact angle of 3 degrees. All obtained results indicate that the described synthetic approach yields densely grafted polymer brushes whose experimental investigations were till now very limited.