Engineering the Properties of Polymer Photonic Crystals with Mesoporous Silicon Templates

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• 作者：Joanna Wang ; Gha Y. Lee ; Rhiannon Kennard ; Giuseppe BarillaroRachel H. Bisiewicz ; Norma A. Cortez Lemus ; Xiaoyu C. Cao ; Emily J. Anglin ; Jennifer S. Park ; Andrea Potocny ; Drew Bernhard ; Jianlin Li ; Michael J. Sailor
• 刊名：Chemistry of Materials
• 出版年：2017
• 出版时间：February 14, 2017
• 年：2017
• 卷：29
• 期：3
• 页码：1263-1272
• 全文大小：656K
• ISSN：1520-5002

文摘

The effect of molecular weight on the rate and extent of melt-infiltration of polystyrene into mesoporous silicon-based photonic crystals is investigated as a function of polymer molecular weight. Polymer viscosity and chain end-to-end (R_ee) distance correlate with the rate and extent of infiltration. High molecular weight (M_w) polystyrene (200 or 400 kDa) infiltrates the mesoporous material in two distinct phases: a rapid phase where the larger pores of the template are filled, followed by a slower phase during which the smaller pores fill. Low molecular weight polystyrene (20 and 35 kDa) fills the pores more uniformly, progressing into the film as a single, relatively distinct front of liquid polymer. Scanning electron microscope (SEM) analyses of cross sections of the films are consistent with the optical measurements, showing a lower extent of infiltration for the higher molecular weight polymers. Removal of the porous Si templates by soaking in a chemical etchant generates free-standing films of nanostructured polymer. The low molecular weight samples display better replication. Partial removal of the template enables tuning of the hydrophobicity of the free-standing polymer films, which is demonstrated with a flexible and chemically stable polyvinylidene fluoride polymer.