Mixed lamellar films: Evolution, commensurability effects, and preferential defect formation
Mixed lamellar films: Evolution, commensurability effects, and preferential defect formation
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DOI：
10.1021/ma9912711
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发表时间：
2000-01-11
期刊：
影响因子：
5.5
通讯作者：
Mays, J
中科院分区：
文献类型：
--
作者：
Huang, E;Mansky, P;Mays, J
用中子反射率和小角中子散射研究了中性聚（苯乙烯-无规-甲基丙烯酸甲酯）（P（S-r-MMA））刷表面上的层状聚（苯乙烯-嵌段-甲基丙烯酸甲酯）（P（S-b-MMA））二嵌段共聚物膜的结构随退火时间和膜厚的变化。在退火时，微相分离迅速发生，分别从中性和空气表面发出垂直和平行的层流。随着样品进一步退火，这种初始生长之后是平行层状结构的量的缓慢增加，同时垂直层状结构的量减少。在长时间退火后，垂直和平行层状结构的量没有显著变化。混合层状结构显示出强烈的可折叠性趋势，膜厚度具有与自然层状周期相等的周期。这是解释通过优先形成的s（1/2）向错具有PS的核心，这决定了观察到的可重复性的趋势。通过场发射扫描电子显微镜观察到这些缺陷的优先形成的薄膜主要由垂直层状。
The structure of lamellar poly(styrene-block-methyl methacrylate), denoted as P(S-b-MMA), diblock copolymer films on neutral poly(styrene-random-methyl methacrylate), denoted as P(S-r-MMA), brush surfaces was examined as a function of annealing time and film thickness using neutron reflectivity and small-angle neutron scattering. Upon annealing, microphase separation occurs quickly with perpendicular and parallel lamellae emanating from the neutral and air surfaces, respectively. This initial growth is followed by a slow increase in the amount of parallel lamellae with a concurrent decrease in the amount of perpendicular lamellae as the samples are annealed further. After long annealing times, the amounts of perpendicular and parallel lamellae do not change significantly. The mixed lamellar structures show a strong commensurability trend with film thickness having a period equal to that of the natural lamellar period. This is explained through the preferential formation of s(1/2) disclinations having PS cores which dictate the observed commensurability trend. The preferential formation of these defects was observed by field emission scanning electron microscopy on films predominantly comprised of perpendicular lamellae.