末端含三甲基硅基树枝状低聚苯的合成与表征

树枝状聚合物是一类结构有序、有特定分子量、末端可带活性官能团的多功能聚合物,其应用研究涉及信息贮存材料、高级催化剂、非线性光学材料、液晶材料、纳米材料、缓释药物载体、传感器材料、污水处理剂、分离膜及流变学改性剂等领域.以含多功能团的低聚苯为中心核,通过过渡金属催化的芳基偶联反应或Diels-Alder环加成反应,经“收敛法”或“发散法”可以制得结构准确、尺寸可控的树枝状聚苯纳米材料;另一方面,由于核心分子结构的多样性,可以设计、合成拓扑形态各异的树枝状聚苯应用于有机发光材料、有机磁性体、碟状液晶、管束状分子通道、分子识别、储氢材料及锂电池等领域,从而丰富其结构与性能关系的研究内容.因此,树枝状聚苯中心核的设计与合成在这类材料的应用研究中显得尤为重要.本工作设计与合成了一类树枝状聚苯的中心核12和13,其分子末端的生长点被三甲基硅基（TMS-）所保护;采用凝胶渗透色谱（GPC）和粉末X射线衍射等分析手段,以及与其母体结构,即末端不含三甲基硅基的模型化合物1,3,5-三（3＇,5＇-二苯基苯基）苯11进行比较,探讨了分子末端的三甲基硅基及其取代位置对树枝状低聚苯的凝胶渗透色谱行为和结晶性的影响.

SYNTHESIS AND CHARACTERIZATION OF POLYPHENYLENE DENDRIMERS CONTAINING TERMINAL TRIMETHYLSILYL GROUPS

Polyphenylene dendrimers 11,12 and 13 containing terminal trimethylsilyl groups have been synthesized by phosphine-free palladium chloride catalyzed Suzuki couplings of 1,3,5-tris(3′,5′-dibromophenyl)benzene 9 with aryl boronic acids 5 and 6.These macromolecules were characterized by Fourier transform infrared (FTIR),nuclear magnetic resonance (NMR) and matrix assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectra.Gel permeation chromatograph (GPC) indicated that the hydrodynamic radium of 12,with trimethylsiliyl (—TMS) groups substituted at para-positions on its terminal benzene rings,was larger than that of 13,with trimethylsiliyl groups substituted at meta-positions on its terminal benzene rings.X-ray powder diffraction patterns showed that dendrimer 12 was of a certain amount of crystallinity and dendrimer 13 was amorphous.