PLLA-PEG1000-PLLA三嵌段共聚物的红外变温研究

以左旋丙交酯(LLA)与聚乙二醇(PEG1000)开环共聚制备的HO-PLLA-PEG-PLLA-OH三嵌段共聚物为样品,采用FTIR,X-Ray,DSC等对样品的结构与性能进行了初步表征.然后以变温红外光谱法在0～185℃范围内对其温敏性谱带做了研究.结果发现,当升温至T=95℃左右时,一些吸收谱带的强度增强(如:在920cm-1,1215cm-1,1294cm-1等附近的谱带),当继续升温至T=165℃时,这些吸收谱带的强度减弱或消失,自然降温至30℃后,这些吸收谱带强度又增强,这种变化与DSC表征一致,因此应归属于结晶相关谱带.同时还观察到:在样品的冷结晶温度区域附近,756cm-1的吸收带强度,在实验条件下发生了不可逆转变.

FTIR Spectra of PLLA-PEG1000-PLLA Tri-block Copolymers at Different Temperatures

In this paper,the tri-block copolymer(PLLA-PEG-PLLA)is prepared by L-Lactide ring-opening polymerization with poly(ethylene glycol)(PEG1000)using Sn(Oct)2 as catalyst,and characterized by FTIR,X-Ray,DSC.Its sensitive bands with temperature are also studied at different temperatures in the ranges of 0~185 ℃ by FTIR.It is found that intensities of some absorbent bands(920 cm-1,1 215 cm-1,1 294 cm-1)have increased from 0 ℃ to 95 ℃,while the temperature go on rising up to 165 ℃,they have decreased or disappeared completely.However,they would increase again after temperature descends to 30 ℃ in freely.These changes are in accord with the results of DSC.Therefore,these bands should be assigned to relation with their crystal.On the conditions of experiment,a strange phenomenon is also observed that the intensity of band at the wavenumbers of 756 cm-1 could not be retrieved completely near the regions of cold crystal temperatures.