共查询到19条相似文献,搜索用时 109 毫秒
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聚乳酸的合成、结构及性能 总被引:15,自引:0,他引:15
常青 《高分子材料科学与工程》1994,10(1):140-143
乳酸经减压蒸馏制得单体丙交酯,再以氧化锌为催化剂聚合得到聚乳酸。单体及聚合物均由结构鉴定证实,对产物的分子量、力学性能及降解等重要性质作了研究。 相似文献
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丙交酯合成条件的研究 总被引:1,自引:0,他引:1
丙交酯作为合成聚乳酸的重要中间体,它的制备是影响开环聚合高分子量PLA的关键因素。反应时间和反应温度是制备丙交酯的两个重要的工艺参数,直接影响丙交酯的产率。本文着重就反应时间对丙交酯产率的影响进行了初步研究,并提出了一种制备丙交酯的优化工艺。 相似文献
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PLA单体--丙交酯合成方法的研究进展 总被引:7,自引:0,他引:7
只有高分子量聚乳酸才能满足组织工程对其强度及其它性能的要求,而丙交酯是制备高分子量聚乳酸的重要原料,其纯度和成本的高低决定了高分子量聚乳酸的质量和价格,20世纪70年代以来,在提高丙交酯的产率,纯度,降低丙交酯的成本方面做了大量的工作,并取得一定的进展,文中综述了制备丙交酯的各种方法和工艺,并讨论了各自的优缺点,提出了制备丙交酯和高分子量聚乳酸的可能发展方向。 相似文献
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微波辐射D,L-丙交酯开环聚合制备聚乳酸 总被引:2,自引:1,他引:1
为得到聚乳酸的最佳制备工艺,利用微波辐射技术实现D,L-丙交酯开环聚合制备聚乳酸,实验考查了催化剂种类和用量,微波辐照功率和时间等工艺参数对产物分子量的影响,以及反应过程中体系温度的变化.研究表明,以连续微波炉作为反应器,催化剂Sn(Oct)2用量为丙交酯单体用量的0.56%(质量分数),在功率为90 W的连续微波辐射下反应10 m in,可获得粘均分子量(Mη)为15.92×104的聚乳酸(PDLLA).与家用微波炉相比,采用连续微波炉反应器,可在较短的反应时间内获得较高产率的聚乳酸产物. 相似文献
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以L-乳酸为原料,通过L-丙交酯(LLA)开环聚合制备了聚L-乳酸(PLLA)。采用FT-IR、1 H-NMR对丙交酯及聚乳酸的结构进行了表征。考察了聚合时间对聚乳酸相对分子量的影响,通过TGA、拉力试验机和失重率对聚乳酸薄膜的性能进行了表征,并研究了聚乳酸薄膜在茶碱为模型药物中的控制释放性能。结果表明,当m(LLA)/m(辛酸亚锡)=10000、聚合温度为l40℃,常压聚合20h可制得粘均分子量为8.14×l04的聚乳酸,其薄膜具有较好的热稳定性和力学性能。聚乳酸薄膜在人工胃液中的降解速率随着分子量的增加而降低。茶碱在聚乳酸薄膜中缓释机理为第二类输送机理(近似零级释放机理)。 相似文献
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单分散微米级聚苯乙烯微球的制备 总被引:1,自引:0,他引:1
以乙醇/异丙醇为分散介质、聚乙烯吡咯烷酮(PVPK-30)为稳定剂、乳酸为共稳定剂及过氧化二苯甲酰(BPO)为引发剂,采用分散聚合的方法,成功制得单分散微米级聚苯乙烯微球,微球粒径均一且粒径范围为2.22-4.15um.研究了乙醇/异丙醇比例、PVPK-30、乳酸、BPO及单体浓度对聚苯乙烯微球粒径及粒径分布的影响,并... 相似文献
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Leela JoshiRajiv Prakash 《Materials Letters》2012,66(1):250-253
This letter is a continuation of our previous work on synthesis of polyindole-gold nanocomposite published in this journal. In the present work, we have synthesized the similar hybrid organo-inorganic composite using a novel interfacial polymerization route at water/dichloromethane interface. The hybrid organo-inorganic composite material is based on conducting polymer, polyindole and gold nanoparticles; the redox character of indole (monomer) and chloroauric acid facilitates the polymerization of monomer. Entirely different morphological and structural features are observed compared to our previous results. The contact of monomer and metal salt acid (chloroauric acid) at the interface results in the formation of polyindole-Au nanocomposite (without any need of template or capping agent) of nanorod morphology encapsulating Au nanoparticles. XRD studies shows semi-crystalline nature of the polymer unlike the amorphous polyindole formed using other methods. Tunable photoluminescence spectra show the potential applications of the composite in the field of organic laser and organic optoelectronics. 相似文献
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无稳定剂和交联剂的情况下,在乙腈中利用蒸馏沉淀聚合的方法制备无交联的聚丙烯酸(polyAA)纳米粒子.不同的反应条件下,考察引发剂偶氮二异丁腈(AIBN)和单体丙烯酸(AA)浓度的影响.结果表明最佳的聚合反应条件为AIBN相对于单体质量2%,AA相对于反应介质体积2.5%,在这个条件下线性polyAA纳米粒子的粒径约为254 nm.此外,以纯化后的polyAA纳米粒子作为种子,在引发剂和AA单体存在的条件下,通过种子蒸馏沉淀聚合可得到大粒径的纳米粒子.由于AA单体中羧基间的氢键作用,AA单体被认为是自身交联剂,氢键导致了AA双胞体的形成.在聚合体系中加入三乙胺,AA单体间的氢键被破坏.结果表明:几乎没有线性polyAA纳米粒子合成,当三乙胺的量超过AA单体时,只能得到凝胶,而得不到纳米粒子. 相似文献
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药物缓释材料聚(乳酸-丙氨酸)的直接法合成与表征 总被引:4,自引:0,他引:4
直接以外消旋乳酸(LA)、L-丙氨酸(Ala)为原料[n(LA):n(Ala)=9:1],采用熔融聚合法合成药物缓释材料聚(乳酸-丙氨酸)共聚物[P(LA-co-Ala)],并用特性黏数、FTIR、1H NMR、GPC、DSC、XRD等手段进行系统表征.熔融共聚中采用一次投料并分次预聚,可生成重均相对分子质量(Mw)达3200(分散度Mw/Mn=1.23)的共聚物,相对分子质量可以达到丙交酯开环共聚法的水平.首次报道了P(LA-co-Ala)]药物缓释材料的DSC与XRD表征结果,其与聚外消旋乳酸(PDLLA)相比,共聚物具有较低的Tg、Tm和结晶度.新方法步骤少、操作简便,且成本更加低廉. 相似文献
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接枝共聚改性是提高聚乳酸性能的一种常用方法,能够扩展其使用范围。从共聚材料种类及性能的角度,分类介绍了近年来利用纤维素、淀粉、壳聚糖、葡聚糖等天然材料和亲水性、温敏性、聚氨基酸类聚合物等合成材料接枝改性聚乳酸的研究进展,分析了各类接枝改性聚乳酸材料的优缺点和应用,展望了该领域未来的发展方向和产业化应用中应该注意的问题,指出在今后聚乳酸基接枝共聚物材料的推广应用中应该关注产品的成本问题。 相似文献
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An interfacial polymerization procedure was developed for the preparation of polymethylcyanoacrylate (PMCA) nanoparticles loaded with triamcinolone acetonide. The nanoparticles were characterized concerning their interior structure, size distribution, drug content, drug release and in vivo distribution. These results (except those for the in vivo distribution) were compared with those obtained with nanoparticles prepared by micell polymerization [5]. Both preparation procedures yielded particles with a mean diameter below 500 nm. The drug content of the nanoparticles prepared by interfacial polymerization ranged from 6,5% w/w to 1,9% w/w depending on the employed monomer concentration in contrast to 0,045% w/w for nanoparticles prepared by micell polymerization [5]. In comparison to microcrystalline substance the drug release from the nanoparticles could be sustained in all cases, but there was no difference in drug release between the nanoparticles prepared by both methods.
After removal of surface adherent drug from nanoparticles prepared by both methods those prepared by interfacial polymerization had an about 12 times higher drug content and the remaining drug amount was released more slowly by these particles. Furthermore, using increasing monomer concentrations during interfacial polymerization (125 - 500 mg/100 ml emulsion) drug release was slowed down, but no further improvement could be achieved for monomer concentrations exceeding 250 mg/100 ml emulsion.
After intravenous injection of 99mTc labeled PMCA nanoparticles into rats they accumulated predominantly in liver, spleen and kidney, a distribution pattern usually found for colloidal particles. 相似文献
After removal of surface adherent drug from nanoparticles prepared by both methods those prepared by interfacial polymerization had an about 12 times higher drug content and the remaining drug amount was released more slowly by these particles. Furthermore, using increasing monomer concentrations during interfacial polymerization (125 - 500 mg/100 ml emulsion) drug release was slowed down, but no further improvement could be achieved for monomer concentrations exceeding 250 mg/100 ml emulsion.
After intravenous injection of 99mTc labeled PMCA nanoparticles into rats they accumulated predominantly in liver, spleen and kidney, a distribution pattern usually found for colloidal particles. 相似文献