【作者】 朱魁；

【导师】 沈之荃； 朱蔚璞；

【作者基本信息】 浙江大学 ， 高分子化学与物理， 2010， 博士

【摘要】 聚酯是一类用途广泛的材料,其中力学、热性能优良的芳香族聚酯作为一种结构性材料主要用于日常生活中,可降解的脂肪族聚酯则广泛用于生物医药领域。缩合聚合是合成聚酯的主要方式,而缩聚过程中的催化剂直接决定聚酯的质量。本文以合成的多种稀土化合物为单组份催化剂,通过熔融缩聚在高温下制备成可降解芳香-脂肪族共聚酯及在较低温下合成了功能化脂肪族聚酯。系统研究了稀土化合物催化缩合聚合的活性,利用1H NMR.FT-IR.GPC.DSC.TGA. DMA.XRD和堆肥降解等手段研究了聚酯的结构与性能。并通过功能基团的化学反应对功能化聚酯进行了初步的修饰。以稀土化合物为催化剂,按对苯二甲酸二甲酯(DMT)同二元醇(EG或BG)先经酯交换再与二元脂肪酸(SUA,AA或SEA)进行酯化然后缩聚的方式合成了多种较高分子量的芳香-脂肪族共聚酯PBTA.PETA.PETSU及PETSE.在合成PBTA时,通过酯交换、酯化反应程度及缩聚产物分子量的比较发现,稀土化合物结合的阴离子部分对反应速度有明显影响,催化活性最高的稀土化合物为硬脂酸稀土。研究硬脂酸钕的浓度([NdSt3]/[DMT]=1-10×10-4)及硬脂酸稀土种类(LaSt3,NdSt3,YSt3,DySt3)对PETA合成中酯交换和缩聚阶段的影响表明,催化剂浓度降低酯交换反应表观反应速率下降；不同稀土元素之间,催化酯交换反应活性按NdSt3>LaSt3>YSt3=DySt3排列。缩聚阶段,催化剂浓度在[NdSt3]/[DMT]=2-10×10-4范围内时聚酯产物的分子量差别较小,表明NdSt3在较低的浓度下仍具有较高的催化活性。稀土元素种类对缩聚阶段的影响不及酯交换阶段明显。对所合成的聚酯结构和性能的研究表明,共聚酯中芳香-脂肪组分的摩尔含量同投料比基本一致,共聚酯为无规聚合物。共聚酯的力学性能、热性能同聚酯的组成密切相关,具体表现为：相同单体组成的不同芳香-脂肪摩尔投料比的共聚酯,芳香族含量增加,玻璃化温度上升,热稳定性变好,降解性能降低。在芳香-脂肪组分按等摩尔比投料共聚时,二元脂肪酸的碳链增长,聚酯玻璃化温度降低,降解速率增加。以三氟甲基磺酸稀土(Ln(OTf)3)为催化剂,在较温和条件下(60-80℃)通过二元醇和(功能基取代)二羧酸的酯化,本体缩聚合成了聚丁二酸癸二酯(PSUADD)和聚酒石酸已二酯(PTAHD).对Ln(OTf)3催化活性的研究表明：PSUADD合成中,Nd(OTf)3和Dy(OTf)3活性较高,聚酯数均分子量高于1.15×104g/mol;合成PTAHD时,Dy(OTf)3、Y(OTf)3、Sc(OTf)3催化性能优异,聚酯数均分子量达到1.0x104g/mol通过链结构分析确认酒石酸中仲羟基未参与缩合聚合,表明Ln(OTf)3催化缩聚合成聚酯时对伯羟基具有较高的选择性。获得的聚合物为多羟基线型功能化聚酯。这些聚酯可通过与酰氯等活泼基团反应对聚酯修饰。通过调整功能单体和丁二酸的摩尔比例,在Dy(OTf)3催化下合成了功能基团含量可调控的聚(丁二酸-co-苹果酸)癸二酯(PMAADD)和聚(丁二酸-co-顺丁烯二酸)癸二酯(PMADD).在PMAADD主链上接枝mPEG获得了两亲接枝聚合物,这种聚合物在水溶液中可形成胶束。PMADD主链上的双键可通过巯基加成反应实现对聚酯的修饰改性。更多还原

【Abstract】 Due to the environmental pollution with solid wastes of plastic materials, aromatic-aliphatic copolyesters combining biodegradability with good use properties are of great interest and could be economically important. On the other hand, special attention has also been paid to the preparation of biodegradable polyester bearing functional pendant groups. The availability of reactive groups along the chains is highly desirable for fine tuning the properties in order to carry drugs, to improve biocompatibility, to control the biodegradation rate and so on. In this dissertation, a series of rare earth compounds were synthesized and used as a single component catalyst for melt (co)polycondensation to prepare aromatic-aliphatic copolyesters and linear functional polyesters. The functional polyesters were modified through the reactivity of pendant functional groups. The resultant polymers have been characterized by GPC,1H NMR, DSC, TGA etc measurementsAromatic-aliphatic copolyester PBTA was synthesized via direct polycondensation from dimethyl terephthalate(DMT), adipic acid(AA) and 1,4-butanediol(BG) with feeding mole ratio of DMT:AA=50:50 in the presence of different rare earth catalysts. Among various neodymium compounds tested, neodymium stearate shows higher catalytic activity and prepared PBTA with weight-average molar mass of 6.01 x104 g/mol. The rare earth elements affect the catalytic activity and Dy[OOC(CH2)16CH3]3 has a little higher activity than other rare earth stearates. The microstructures, thermal and mechanical properties of PBTA were characterized and analyzed.Rare earth stearates were applied to the polycondensation of dimethyl terephthalate(DMT), adipic acid(AA) and 1,2-ethandiol(EG) to produce PETA copolyester. The apparent rate constant of transesterization decreased linearly and molecular weight of PETA increased at first and drop obviously with decreasing catalyst concentration.A series of PETA with various feeding mole ratio of DMT/AA (30/70 to 80/20) were synthesized in the presence of neodymium stearate. The molecular weight, microstructures such as number-average sequence lengths of ethylene adipate unit(SLEA) and ethylene terephthalate unit(SLET) and degree of randomness(R), thermal and mechanical properties, biodegradation rate in composting tests were measured, showing some relationship with the composition of the copolyester.Copolyester PETSU, PETA and PETSE were prepared from succinic acid(SUA), adipic acid(AA), sebacic acid (SEA) with DMT and EG respectively by neodymium stearate. The length of alkyl group of the aliphatic acid affects the properties and biodegradation rate of the resultant polymers obviously.Melt (co)polycondensation of succinic acid, substituent dicarboxylic acid such as tartaric acid, malic acid and unsaturated maleic acid with aliphatic diols were carried out with rare earth triflates(Ln(OTf)3) at mild condition(60-80℃) to synthesis functional polyesters having pendent hydroxyl groups or carbon-carbon double bond by one-pot. The content of functional group in the main chain of the polyester can be controlled by feeding mole ratio of succinic acid and functional monomer. Modifications of polyesters were successfully conducted via the reaction of pendent hydroxyl group with carbonyl chloride, carboxylic group or carbon-carbon double bond with mercapto group.更多还原