天然氨基酸作用下2,2-二甲基三亚甲基碳酸酯的开环聚合

研究了几种中性天然氨基酸存在下2,2-二甲基-三亚甲基环碳酸酯(DTC)的开环聚合反应。1H-NMR和端基滴定分析表明,在聚合反应过程中,DTC上的酰氧键断裂,氨基酸通过氨基接在聚(2,2-二甲基-三亚甲基碳酸酯)链上。3-氨基丙酸、4-氨基丁酸、6-氨基己酸等存在时,DTC的聚合反应也可以发生,但单体的转化率和聚合物的分子量低于天然氨基酸引发的聚合反应。     

聚2,2-二甲基三亚甲基碳酸酯与壳寡糖的接枝共聚反应研究

用新戊二醇和三光气为原料,反应生成2,2-二甲基三亚甲基碳酸酯.再以四氢呋喃为溶剂,酶为催化剂引发聚2,2-二甲基三亚甲基碳酸酯（PDTC）与壳寡糖接枝生成接枝共聚物.研究了温度、时间、配比对接枝共聚物的产率和分子量的影响.就产率而言,最佳反应条件是60℃、-NH2/DTC的摩尔比值为1∶10、36 h、DTC/酶的质量比值为200;就重均分子量而言,最佳反应条件是60℃、-NH2/DTC摩尔比为1∶10、36 h、DTC/酶质量比值为150.对产品进行红外光谱、凝胶色谱与溶解性能测试.     

聚三亚甲基碳酸酯的研究进展

聚三亚甲基碳酸酯具有良好的生物降解性能及生物相容性,是一种重要的生物降解医用高分子材料,在生物医用领域具有较大的应用前景。本文结合近年来的研究进展,综述了阳离子开环聚合、阴离子开环聚合、配位聚合、酶促开环聚合以及微波开环聚合等方法在聚三亚甲基碳酸酯制备过程中的应用,总结了聚三亚甲基碳酸酯的分子量与物理性能的关系,并重点讨论了聚三亚甲基碳酸酯的体内外降解性能,详细描述了分子量及脂肪酶对聚三亚甲基碳酸酯降解行为的影响,最后总结了聚三亚甲基碳酸酯在生物医用领域的应用。     

离子液体支载稀土催化剂催化 2,2-二甲基-三亚甲基碳酸酯均聚及其与ε-己内酯的共聚

首次合成了离子液体支载稀土催化剂,并探讨了其催化2,2-二甲基-三亚甲基碳酸酯(DTC)均聚及其与ε-己内酯(ε-CL)的共聚,结果表明该新型催化剂能有效地催化DTC的均聚及其与ε-CL的共聚.研究了不同稀土以及加料顺序等反应条件对聚合的影响,发现轻稀土的催化活性比重稀土高,其中离子液体支载La催化剂的催化活性最高,而通过控制不同的加料顺序可以制备DTC和ε-CL的无规及嵌段共聚物.对共聚物结构进行了表征.     

聚三亚甲基碳酸酯的生物相容性研究

以实验室自制的聚三亚甲基碳酸酯(PTMC)为研究对象,通过测定聚三亚甲基碳酸酯在体外酶解过程中降解液pH变化,考察其在降解过程中是否产生酸性降解产物;通过MTS法考察聚三亚甲基碳酸酯的体外细胞毒性;通过HE染色的方法考察聚三亚甲基碳酸酯在大鼠体内埋植部位的皮肤刺激性,进而考察聚三亚甲基碳酸酯的生物相容性。结果表明:PTMC在降解过程中不产生酸性降解产物,可避免埋植部位无菌炎症的产生。同时不同分子量的PTMC可以存在于皮下组织而不会造成伤害,因此聚三亚甲基碳酸酯具有良好的生物相容性,可安全植入体内。     

纳米级固定化猪胰脂肪酶催化三亚甲基碳酸酯的开环聚合研究

以纳米级固定化猪胰脂肪酶(IMPPL)催化三亚甲基碳酸酯(TMC)的开环聚合,研究了IMPPL浓度、聚合反应温度和聚合反应时间对聚三亚甲基碳酸酯(PTMC)分子量和产率的影响.同时也研究了回收再利用的IMPPL对TMC开环聚合的催化作用以及IMPPL对PTMC的降解作用.实验结果表明,IMPPL不仅在60～100℃能有效地催化TMC的开环聚合,而且在较高的温度下IMPPL可以有效地催化PTMC的降解.回收使用的固定化酶可表现较高的催化活性及重复利用性.     

三(2,6-二叔丁基-4-甲基-苯氧基)镧催化ε-己内酯低温聚合特征及与环碳酸酯嵌段共聚

摘要用三(2,6-二叔丁基-4-甲基-苯氧基)镧[La(OAr)₃]在-15 ℃引发ε-己内酯(CL)的开环聚合, 发现聚合体系具有活性聚合特征. 在第二步聚合过程中继续补加第二种单体三亚甲基环碳酸酯(TMC)或二甲基三亚甲基环碳酸酯(DTC), 可得到CL与环碳酸酯的嵌段共聚物.     

聚三亚甲基碳酸酯的改性研究

聚三亚甲基碳酸酯具有良好的生物降解性能及生物相容性,是一种重要的生物降解医用高分子材料,在生物医用领域具有巨大的潜在应用。本文结合近几年的研究进展,综述了聚三亚甲基碳酸酯改性的三大类方法,详细介绍了聚三亚甲基碳酸酯的功能化方法与途径、讨论了聚三亚甲基碳酸酯与不同类别单体共聚改性的研究现状及性能变化,并总结了共混改性对聚三亚甲基碳酸酯性能的影响,最后介绍了改性后的聚三亚甲基碳酸酯在生物医用领域的应用。     

苄醇存在下脂肪叔胺催化内酯开环聚合

为研究脂肪叔胺结构对内酯开环聚合规律的影响,以三乙胺( TEA)、N,N,N′,N′-四甲基乙二胺(TMEDA)、N,N,N′,N″,N″-五甲基二亚乙基三胺(PM DTA)3种不同结构的叔胺催化碳酸三亚甲基酯(TMC)和左旋丙交酯( L-LA)开环聚合.结果显示,在55℃的THF溶液中,以苄醇为引发剂,3种叔胺均能催...     

杯[6]芳烃钪配合物催化DTC开环聚合动力学及其机理

以对叔丁基杯[6]芳烃和异丙氧基钪为原料, 合成了对叔丁基杯[6]芳烃钪配合物, 该配合物可在温和条件下单组分引发2,2－二甲基三亚甲基环碳酸酯(DTC)开环聚合, 制备重均分子量为33700, 分子量分布为1.21的聚合产物. 动力学研究表明该聚合反应对单体和催化剂浓度均呈一次方关系, 表观活化能为22.7 kJ/mol; 通过1H NMR研究聚合物端基, 表明单体的开环机理为Sc-O活性中心引发的酰氧键断裂开环.     

RING-OPENING POLYMERIZATION OF TRIMETHYLENE CARBONATE CATALYZED BY NOVEL SINGLE COMPONENT RARE EARTH CALIXARENE COMPLEXES

In this paper, ring-opening polymerization of trimethylene carbonate (TMC) with rare earth (Nd, Y, La) p-tert-butylcalix[n]arene (n=4, 6, and 8) complexes as catalysts has been studied. Poly(trimethylene carbonate) (PTMC) with Mv of 21,400 was produced by bulk polymerization under the conditions as follows: [TMC]0/[Nd] (molar ratio)=1000,80℃,8h. Mechanism study reveals that the polymerization proceeds via a coordination mechanism.     

Rare earth complexes [Ln(EDBP)<Subscript>2</Subscript>(DME)Na(DME)<Subscript>3</Subscript>] as catalysts for the polymerization of 2,2-dimethyltrimethylene carbonate

The biphenol based discrete ion-pair rare earth complexes,[Ln（EDBP）₂（DME）Na（DME）₃][Ln=Er（1）,Yb（2）, Sm（3）],were prepared and used as catalysts for the ring-opening polymerization（ROP）of 2,2-dimethyltrimethylene carbonate（DTC）.Three complexes show moderate activities for the polymerization,and the catalytic activities increase in the following sequence:（Yb2 elimination was prepared.     

Rapid synthesis of poly(trimethylene carbonate) by microwave-assisted ring-opening polymerization

Poly(trimethylene carbonate) (PTMC) was synthesized successfully by microwave-assisted ring-opening polymerization of trimethylene carbonate. The polymerizations were carried out in a single-mode microwave oven using ethylene glycol (EG) as the initiator in the absence of any metallic compound catalyst. The temperature-time profiles of the reaction mixture were investigated at different power levels and EG concentrations. The molar mass of the resulting PTMC and TMC monomer conversion by the microwave method is higher than those by the conventional method. Thermal properties of the resulting polymers were studied by differential scanning calorimetry. Microwave irradiation proved to be an effective and efficient method for the preparation of PTMC.     

Ring-opening polymerization of 2,2-dimethyltrimethylene carbonate using rare earth aryl oxides substituted by alkyl groups

Single component rare earth aryl oxides substituted by various alkyl groups [Ln(OAr)3] such as methyl,isopropyl,and tertbutyl have been developed to initiate the ring-opening polymerization of 2,2-dimethyltrimethylene carbonate(DTC).The catalytic activity of rare earth aryl oxides,characteristics of the ring-opening polymerization as well as the polymerization kinetics and mechanism were intensively examined.The experimental results turn out that the catalytic activity of Ln(OAr)3 changes in good concordanc...     

Rare Earth Complex Initiated Ring-Opening Polymerization of 2,2-Dimethyltrimethylene Carbonate

Aliphatic polycarbonate is a series of useful biodegradable materials attracting more interests recently. Poly(2,2-dimethyltrimethylene carbonate) (polyDTC) has been studied for a long time. Polymerization of DTC can be catalyzed by alkyl metals1, trifluoromethanesulfonic acid and its esters2, alcohol/methylaluminum diphenolate system3 and etc. Herein tris(2,6-di-tert-butyl-4-methylphenoxo) lanthanides (Ln(OAr)3, Ln=La, Nd) are firstly applied to initiate the polymerization of DTC. Ln(O…     

Highly efficient metal‐free organic catalysts to design new Environmentally‐friendly starch‐based blends

A one‐step process is reported to directly synthesize blends of poly(trimethylene carbonate) (PTMC) with a modified granular starch. Trimethylene Carbonate (TMC) ring‐opening polymerization is performed in the presence of native starch particles in bulk conditions at 150 °C and the efficiency of metal‐free organic catalysts (TBD and phosphazene superbases P1‐t‐Oct, P2‐t‐bu, and P4‐t‐bu) are investigated to replace the organo‐metallic stannous octanoate initiator. TMC monomer is successively converted into PTMC and the robustness of organic catalysts is highlighted with significant activities at very low concentrations (<100 ppm), where stannous octanoate is inefficient. Reactivity of starch toward TMC ROP is deeply investigated by NMR techniques and a starch‐graft‐PTMC is indirectly evidenced. Starch substitution degree reaches 0.9% indicating that PTMC grafting only occurs at the surface of swollen granular starch. PTMC graft length from the starch surface remained low in the range 2–12 and model ROP reactions highlight the role of TMC hydrolysis on PTMC graft length. Despite low PTMC grafts, a fine dispersion of intact starch particles into the PTMC matrix is evidenced. Consequently, metal‐free organic catalysts at low concentrations are promising candidates for synthesizing blends of PTMC with high loadings of surface‐modified starch (32% by weight) in 2 min within a one‐step process. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 493–503     

Copolymerization of carbon dioxide and oxetane catalyzed by aluminum porphyrin complex system

Tetraphenylporphinatoaluminum chloride ([TPP]AlCl) catalyst and tetra-n-butylammonium bromide (TBAB) cocatalyst system is effective for the copolymerization of CO₂ and oxetane even under low CO₂ pressure (~2 MPa). In the presence of toluene as a solvent, poly(trimethylene carbonate) (PTMC) containing >99% of carbonate linkages with M_n = 8600 and M_w/M_n = 1.70 was synthesized. This is the first report of PTMC formation with excellent ratio of carbonate linkages from oxetane and CO₂. According to the kinetic analysis, proton nuclear magnetic resonance (¹H NMR) and matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) measurements of the products, PTMC was mainly synthesized via (i) the trimethylene carbonate (TMC) formation from CO₂ and oxetane and (ii) the successive ring-opening polymerization of TMC.     

Enzymatic ring-opening polymerization of 2,2-dimethyltrimethylene carbonate catalyzed by PPL immobilized on silica nanoparticles

Silica nanoparticles were first used as the carrier for the porcine pancreas lipase (PPL) immobilization. The result of transmission electron microscopy (TEM) showed that the immobilized lipase was still in nanosize after enzyme immobilization. The ring-opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) catalyzed by this immobilized PPL (IMPPL) was explored. ¹H NMR spectra suggested no evidence of decarboxylation during propagation. Influences of IMPPL concentration and reaction temperature on the molecular weight and yield of poly(DTC) were studied. The recovery and reuse of IMPPL for the ring-opening polymerization of DTC was also investigated. The recycling IMPPL showed even higher catalytic activity and a higher molecular weight of polycarbonate could be achieved.     

Kinetics and mechanism studies on scandium calix[6]arene complex initiating ring-opening polymerization of 2,2-dimethyltrimethylene carbonate

Scandium p-tert-butylcalix[6]arene complex has been synthesized from scandium isopropoxide and p-tert-butylcalix[6]arene and used as a single component initiator for the first time. The polymerization of 2,2-dimethyltrimethylene carbonate (DTC) using this complex can proceed under mild conditions. Poly (2,2-dimethyltrimethylene carbonate) (PolyDTC) with weight-average molecular weight of 33700 and molecular weight distribution of 1.21 can be prepared. Kinetics study indicates that the polymeri- zation rate is first order with respect to both monomer and initiator concentrations, and the apparent activation energy of the polymerization is 22.7 kJ/mol. 1H NMR spectrum of the polymer reveals that the monomer ring opens via acyl-oxygen bond cleavage leading to an active center of Sc-O.