Reduced Lateral Confinement and Its Effect on Stability in Patterned Strong Polyelectrolyte Brushes.
Reduced Lateral Confinement and Its Effect on Stability in Patterned Strong Polyelectrolyte Brushes.
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DOI：
10.1021/acs.langmuir.7b00165
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发表时间：
2017-03
期刊：
影响因子：
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通讯作者：
Wei‐Liang Chen;M. Menzel;Tsukasa Watanabe;O. Prucker;J. Rühe;C. Ober
中科院分区：
文献类型：
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作者：
Wei‐Liang Chen;M. Menzel;Tsukasa Watanabe;O. Prucker;J. Rühe;C. Ober
研究了强磁刷（PEBs）的稳定性，在散装和图案化的结构。采用单电子转移活性自由基聚合法合成了厚度大于100 nm的聚[（2-甲基丙烯酰氧基）乙基]三甲基氯化铵厚膜。通过自上而下（TD）或自下而上（BU）的方法，使用深紫外光刻确定刷图案化，其特征小至200 nm。刷子浸泡在水中的pH值或温度条件下的范围内，和水解监测通过干燥状态的椭圆偏振和原子力显微镜测量。BU图案显示较小图案的降解减少，这是由于在这样的尺寸下应力松弛增加。与已经松弛的BU图案化刷相比，TD图案化刷具有由正交光刻的使用产生的垂直结构。有人发现，TD过程诱导侧壁上的交联，其随后强化侧壁材料。聚合物刷的这种改性阻碍了图案的应力松弛，并且降解趋势变得与图案尺寸无关。通过适当的调整，侧壁上的交联被最小化，并且降解趋势再次依赖于弛豫。
The stability of strong polyelectrolyte brushes (PEBs) was studied in bulk and in patterned structures. Thick PEBs of poly([(2-methacryloyloxy)ethyl]trimethylammonium chloride) with thicknesses >100 nm were synthesized using single electron transfer living radical polymerization. Brush patterning was identified using deep-ultraviolet photolithography by means of either a top-down (TD) or bottom-up (BU) method, with features as small as 200 nm. The brushes were soaked in water under a range of pH or temperature conditions, and the hydrolysis was monitored through dry-state ellipsometry and atomic force microscopy measurements. BU patterns showed reduced degrafting for smaller patterns, which was attributed to increased stress relaxation at such dimensions. In contrast to the already relaxed BU-patterned brush, a TD-patterned brush possesses perpendicular structures that result from the use of orthogonal lithography. It was found that the TD process induces cross-linking on the sidewall, which subsequently fortifies the sidewall materials. This modification of the polymer brushes hindered the stress relaxation of the patterns, and the degrafting trends became irrelevant to the pattern sizes. With proper tuning, the cross-linking on the sidewall was minimized and the degrafting trends were again relaxation-dependent.