苯丙炔酸低聚物的合成及性能

极性-共轭双取代乙炔-苯丙炔酸在Pd(PPh3)2Cl2催化下直接通过易位催化机理聚合为低聚物.单体苯丙炔酸由两步制得,先通过液溴和肉桂酸的加成反应得到二溴代苯丙酸,然后消去两分子溴化氢得到单体.通过红外光谱(IR)、核磁共振(NMR)对单体及低聚物的结构进行了表征.凝胶渗透色谱(GPC)结果显示,聚合反应以甲苯作溶剂,75℃下效果最好,产率中等.这种共轭低聚物可以溶于四氢呋喃(THF)等极性溶剂,TGA结果表明低聚物热稳定性高.紫外可见吸收光谱(UV-Vis)显示,由于聚合后共轭主链大大增长,苯丙炔酸低聚物骨架上电子的跃迁使得低聚物的四氢呋喃溶液在波长高于310 nm光谱的区域中有吸收.荧光光谱(FS)显示,低聚物的四氢呋喃溶液在342 nm激发光下发蓝光,420 nm处有特征荧光发射峰.

SYNTHESIS AND PROPERTIES OF PHENYLPROPIOLIC ACID OLIGOMERS

A disubstituted acetylene with both polar and conjugate groups, phenylpropiolic acid ( PhPA ) , was directly polymerized into poly ( phenylpropiolic acid) oligomer through metathesis polymerization with Pd (PPh_3)_2 Cl_2 as catalyst and toluene as solvent, while the monomer PhPA was synthesized by the addition reaction of cinnamic acid with bromine and the followed elimination of hydrogen bromide. The polymerizations of PhPA showed a moderate yield of oligomer at 75℃ and in toluene solvent. The structures of both PhPA and oligomer were confirmed by IR and ~1H-NMR. For example,the absorption band at 1620 cm~(-1) associating with C = C stretching appears in the spectrum of oligomer, instead of 2210 cm~(-1) associating with C=C stretching in the spectrum of PhPA. The oligomer is soluble in common polar solvents and has high thermal stability. Comparison of the absorption spectra of the oligomer with its monomer reveals that the absorption of the oligomer in the spectral region beyond 310 nm is associated with the electronic transitions of oligomer skeleton. On the fluorescence investigation of the oligomer,THF solutions of oligomer emit blue light and show the peak emissions at 420 nm at different concentrations when excited at 342 nm. At the concentration of 0. 04 mmol/L of oligomer, its emission indicates the biggest intensity.