Preparation of cholesteric (hydroxypropyl) cellulose/polymer networks and ion-mediated control of their optical properties
Preparation of cholesteric (hydroxypropyl) cellulose/polymer networks and ion-mediated control of their optical properties
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DOI：
10.1021/bm060567t
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发表时间：
2006-11-13
影响因子：
6.2
通讯作者：
Miyashita, Yoshiharu
中科院分区：
文献类型：
--
作者：
Chiba, Ryotaro;Nishio, Yoshiyuki;Miyashita, Yoshiharu
以含交联剂的甲基丙烯酸酯单体/甲醇/水(质量比为2：1：2)为混合溶剂，通过甲基丙烯酸酯单体的光聚合反应，将羟丙基纤维素(HPC)的液晶溶液以薄膜形式合成了HPC/乙烯基聚合物网络。以甲基丙烯酸二乙二醇单甲醚(DEGMEM)或甲基丙烯酸2-羟丙酯(HPMA)为聚合单体，四(乙二醇二丙烯酸酯)和戊二醛分别为单体和HPC的交联剂。HPC/PDEGMEM和HPC/PHPMA聚合物复合膜在起始溶液中HPC的浓度约为60-70wt%时，由于胆甾体螺旋排列相继进入网络体系而产生的选择性光反射，使其呈虹彩状着色。当胆固醇膜在含有无机中性盐的水中浸泡和膨胀时，它们的颜色和光学混浊度会根据受孕离子的杂化强度而变化。这种离子效应可以解释为与以前在高碳酸盐水溶液的胆甾相螺距和较低的临界溶液温度共存的盐类依赖关系中发现的基本相同。还证明了在矩形样品的两边之间施加实际大小的电势可以改变膨胀网络的视觉外观。
Hydroxypropyl) cellulose (HPC)/vinyl polymer networks were synthesized in film form from liquid-crystalline solutions of HPC in a mixed solvent of methacrylate monomer/methanol/water (2:1:2 in weight) containing cross-linking agents, via photopolymerization of the methacrylate monomer. Di(ethylene glycol) monomethyl ether methacrylate (DEGMEM) or 2-hydroxypropyl methacrylate (HPMA) was used as the polymerizing monomer, and tetra(ethylene glycol) diacrylate and glutaraldehyde were the cross-linkers for the monomers and HPC, respectively. The polymer composite films, HPC/PDEGMEM and HPC/PHPMA, prepared at ca. 60-70 wt % concentrations of HPC in the starting solutions, were iridescently colored due to the selective light reflection, originating from the cholesteric helical arrangement carried over successively into the network system. When the cholesteric films were immersed and swollen in water containing an inorganic neutral salt, their coloration and optical turbidity varied according to a strength of 'chaotropicity' of the impregnant ions. This ionic effect may be interpreted as essentially identical with that found formerly in the coexistent salt-sort dependence of the cholesteric pitch and lower critical solution temperature for HPC aqueous solutions. It is also demonstrated that visual appearance of the swollen networks can be changed by application of an electric potential of practical magnitude between both edges of the samples of rectangular shape.