摘要
合成了一种以二胺为基础的可聚合凝胶因子 4,4′ 二 (α 甲基丙烯酰氧基 1,3 亚乙氧基羰基丙酰氨基 )二苯甲烷 (BMDM) ,利用在特定结构区域的非共价键相互作用自组装形成有序的三维纤维网络 ,使有机溶剂凝胶化 .并利用紫外光引发聚合 ,“锁定”凝胶网络 ,形成稳定的有序高级结构 .光聚合后 ,分子凝胶的稳定时间超过 1年 ;而光聚合前 ,分子凝胶的稳定时间一般只有几天到几十天 .由电镜和偏光显微镜研究的凝胶形态学表明 ,凝胶中存在由相互缠结的三维纤维网络构成的球晶 .DSC研究表明 ,未聚合的分子凝胶中球晶结构的解缔 (peak 1)须克服一个势垒 ,势能为ΔH =0 .8kJ·mol-1,这主要是一种范德华弱相互作用 .而发生的凝胶—溶胶相转变 (peak 2 ) ,则说明了自组装纤维中BMDM分子间存在氢键等次价键相互作用 .这种次价键能即为凝胶—溶胶相转变热焓ΔH =2 2 .3kJ·mol-1.聚合凝胶只有体积相变而无凝胶—溶胶相转变 ,且聚合凝胶的体积相变温度要比光聚合前的凝胶—溶胶相转变温度高出约为 110～ 12 0℃ .研究干聚合凝胶在丙酮中的溶胀特性发现 ,其溶胀过程遵循二级溶胀动力学 ,影响该凝胶溶胀行为的因素主要是交联程度 .
Polymerizable gelator, 4,4-bis(alpha-methylacryloyloxy-1,3-ethyleneoxycarbonylpropionamido) diphenyl methane (BMDM) based on binary amine, was prepared and self-assembled into elongated fibers in organic solvents via non-covalent interaction. These fibers are able to aggregate further into three-dimensional networks, causing organic solvents to gelatinize. By photopolymerization of the gelled solution, the scaffoldlike structure of the gels was locked and the gels formed more stable well-ordered superstructure. The stable time of the polymerized gels is more than one year. However, the stable time of the unpolymerized. molecular gels is only from several days to several weeks. The studies of polarized optical microscopy and TEM indicate the formation of spherulites undergoing aggregation of self-assembled fibers. It was found by DSC that the potential barrier (DeltaH) for disassociation of spherulites formed by van der Waals interaction was 0.8 kJ(.)mol(-1)(Peak 1) and the enthalpy (DeltaH) of gel-sol phase transition for fiber aggregated by hydrogen bonding was 22.3 kJ(.)mol(-1)(Peak 2). For polymerized gels there is only a volume phase transition, without a gel-sol phase transition. The temperature of volume phase transition for polymerized gels is about 110 similar to 120 degreesC higher than that of the unirradiated gels. Swelling behavior of the dried polymerized gels follows Schott second-order diffusion kinetics. The degree of cross-linking is a main factor influencing the swelling behavior of the gels.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2002年第9期1700-1706,共7页
Acta Chimica Sinica
基金
国家自然科学基金 (No .2 99740 12 )资助项目
