Itoh Toshio, Shichi Tetsuya, Yui Tatsuto, Takahashi Hiroki, Inui Yoshihisa, Takagi Katsuhiko
Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan.
J Phys Chem B. 2005 Mar 3;109(8):3199-206. doi: 10.1021/jp045410e.
The present study is an investigation of a reversible thermal color change induced in lamella hybrids of poly(diacetylenecarboxylates) incorporated in layered double hydroxide (LDH) nanosheets. These poly-[m,n]/LDH hybrids prepared by the photo- or gamma-ray-induced polymerization of diacetylenecarboxylates, i.e., CH(3)(CH(2))(m)()(-)(1)CC-CC(CH(2))(n)()(-)(1)CO(2)(-) (mono-[m,n]), and intercalated in LDH lamella sheets, were observed to develop colors ranging from yellow to blue. The change in color was found to depend greatly on the alkyl carbon numbers of the mono-[m,n] (m,n = 10,11; 5,11; 10,5; 16,1) values. Moreover, the conformational alignment of the mono-[m,n] within the LDH was observed to be a crucial factor in color development, which was greatly affected by the intercalation degrees and extent of poly(ene-yne) linkage elongation of the polymers. For the poly-[m,n]/LDH hybrids investigated, a reversible color change was found to occur repeatedly and remarkably for the poly-[10,11]/LDH hybrid. This color change occurred at temperatures between ca. 20 and 80 degrees C back and forth from purple red to bright orange, in stark contrast to the irreversible color change for poly-[10,11] without LDH. Moreover, DSC and Raman spectroscopic studies of the LDH hybrids showed that the thermochromic temperature corresponded to the phase transition temperature of 80 degrees C. XRD analysis also indicated that the poly-[m,n]/LDH hybrid could retain its lamella structure during such thermochromic color changes, enabling conformational recovery in the polymer chains by a cooling down of the hybrids to temperatures lower than the transition temperature, while the nonhybrid poly-[10,11] powders exhibited an irreversible color change at 60 degrees C, above which the polymer powder turned amorphous.
本研究旨在探究层状双氢氧化物（LDH）纳米片中掺入的聚（二乙炔羧酸盐）薄片杂化物中诱导的可逆热致变色现象。这些通过二乙炔羧酸盐（即CH(3)(CH(2))(m)()(-)(1)CC - CC(CH(2))(n)()(-)(1)CO(2)(-)（单-[m,n]））的光诱导或γ射线诱导聚合制备并插层在LDH薄片中的聚-[m,n]/LDH杂化物，被观察到呈现出从黄色到蓝色的颜色变化。发现颜色变化在很大程度上取决于单-[m,n]（m,n = 10,11；5,11；10,5；16,1）值的烷基碳原子数。此外，观察到单-[m,n]在LDH内的构象排列是颜色形成的关键因素，这受到聚合物的插层程度和聚（烯 - 炔）键伸长程度的极大影响。对于所研究的聚-[m,n]/LDH杂化物，发现聚-[10,11]/LDH杂化物反复且显著地发生可逆颜色变化。这种颜色变化在大约20至80摄氏度之间反复出现，从紫红色变为亮橙色，这与不含LDH的聚-[10,11]的不可逆颜色变化形成鲜明对比。此外，对LDH杂化物的差示扫描量热法（DSC）和拉曼光谱研究表明，热致变色温度对应于80摄氏度的相变温度。X射线衍射（XRD）分析还表明，聚-[m,n]/LDH杂化物在这种热致变色过程中能够保持其薄片结构，通过将杂化物冷却至低于转变温度，聚合物链能够实现构象恢复，而未杂化的聚-[10,11]粉末在60摄氏度时呈现不可逆颜色变化，高于该温度聚合物粉末变为无定形。
