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由3,4-二羟基肉桂酸(DHCA)与D,L-乳酸(LA)经熔融缩聚法得到了新型可生物降解聚酯P(DHCA-co-LA),采用傅立叶变换红外(FTIR),核磁共振(1H-NMR)和凝胶渗透色谱(GPC)对该共聚物的组成与相对分子量进行表征,结果表明其结构明确.改变DHCA与LA单体的配比,得到的P(DHCA-co-LA)的分子量和分子量分布在同一数量级.通过差示扫描量热仪(DSC)、紫外(UV)和荧光光谱研究了共聚物的热性能、紫外与荧光性能,结果表明,P(DHCA-co-LA)有明显的玻璃化转变温度(Tg),随LA的投料比从0增加至50 mol%时,其Tg从132.26℃下降至99.12℃;当LA的投料比为20 mol%时,所得到的聚酯型共聚物溶液呈现最强的荧光强度;在紫外光照下,共聚物可进行环加成反应,但交联度总体较低;紫外光照65 min后,在荧光显微镜下观察到交联颗粒形态稳定、有较强的荧光.X-射线衍射(XRD)测定结果显示,由结晶性DHCA和LA共聚形成的P(DHCA-co-LA)为无定形聚合物,有利于生物降解.共聚物在土壤中的降解实验表明,其降解速度随体系中LA含量的增加而减缓.
A novel biodegradable polyester P (DHCA-co-LA) was obtained by melt polycondensation of 3,4-dihydroxycinnamic acid (DHCA) and D, L- lactic acid (LA). Fourier transform infrared (FTIR) The structure and relative molecular weight of the copolymer were characterized by 1H-NMR and GPC. The results showed that the structure of the copolymer was clear. When the ratio of DHCA to LA monomer was changed, the ratio of P (DHCA-co -LA) in the same order of magnitude.The thermal, UV and fluorescence properties of the copolymer were investigated by differential scanning calorimetry (DSC), ultraviolet (UV) and fluorescence spectroscopy.The results showed that P (DHCA- co-LA) had a significant glass transition temperature (Tg). The Tg decreased from 132.26 ° C to 99.12 ° C as the feed ratio of LA increased from 0 to 50 mol%. When the feed ratio of LA was 20 mol% The resulting polyester copolymer solution showed the strongest fluorescence intensity; under UV light irradiation, the copolymer could undergo cycloaddition reaction, but the crosslinking degree was generally low. After UV light irradiation for 65 min, it was observed under a fluorescence microscope Crosslinked particles were stable in morphology and strong in fluorescence.X-ray diffraction (XRD) results showed that P (DHCA-co-LA) formed by the copolymerization of crystalline DHCA and LA was none Deformation polymers are favorable for biodegradation.The degradation experiments of copolymers in soil show that their degradation rate slows down with the increase of LA content in the system.