聚乳酸/聚丙二醇多嵌段共聚物的合成及表征

以乳酸为原料,通过缩合聚合合成了齐聚乳酸(OLA);以1,6-己二异氰酸酯为扩链剂,扩链OLA和聚丙二醇(PPG)得到多嵌段共聚物(OLA-b-PPG)。采用核磁共振氢谱(1 H-NMR)、傅里叶红外光谱(FT-IR)表征嵌段共聚物的结构;由凝胶渗透色谱(GPC)测定嵌段共聚物的分子量及分子量分布;采用热重分析法(TGA)和示差扫描量热法(DSC)对聚合物的热性能进行了表征;通过拉伸实验测试了聚合物的力学性能。结果表明:OLA和PPG能够通过1,6-己二异氰酸酯扩链制得多嵌段共聚物OLA-b-PPG。OLA-b-PPG的重均分子量为33463g/mol,分子量分布为1.93。与OLA相比,OLA-b-PPG熔点降低,为126℃。OLA-b-PPG的断裂强度为12.2±0.3MPa,断裂延伸率为(3.5±0.5)%。     

用变温红外研究聚乳酸嵌段共聚物生成过程中的化学反应

本文采用熔融缩聚法合成一定分子量的聚乳酸(PLA),采用聚己内酯多元醇(PCL)的聚氨酯预聚体进行共聚反应,以制得PLA-PCL嵌段共聚物.采用变温红外研究了PLA预聚体与PCL预聚体的反应活性,并研究了共聚产物的分子量.结果表明,PLA预聚体与PCL预聚体具有很高的反应活性,共聚后PLA的分子量有大幅度提高.     

以乙基黄原酸丙酸乙酯为链转移剂的PMMA-b-PS的可逆加成断链转移自由基聚合

将乙基黄原酸丙酸乙酯作为链转移剂,进行甲基丙烯酸甲酯(MMA)的可逆加成断链转移自由基聚合(RAFT),并将得到的产物作为大分子链转移剂,加入第二单体苯乙烯(St)进行扩链反应,制备了PMMA-b-PS嵌段共聚物。通过红外光谱、核磁共振、凝胶渗透色谱、热重分析和差示扫描量热等测试手段对制备的PMMA-b-PS嵌段共聚物进行分析表征。研究表明,第二单体St与大分子链转移剂发生了共聚,形成了嵌段共聚物;制备所得PMMA-b-PS嵌段共聚物的数均相对分子质量明显增加,相对分子质量分布变宽,初始热分解温度明显提高,玻璃化转变温度介于PMMA与PS的玻璃化转变温度之间。     

可生物降解多嵌段共聚物P(LLA-mb-BSA)的制备与性能

本文以直接缩聚制得的聚乳酸(PLLA)和聚丁二酸己二酸丁二醇酯(PBSA)预聚物为原料,以1,4-苯基二噁唑啉(PBO)及六亚甲基二异氰酸酯(HDI)为双扩链/偶联剂,采用扩链/偶联法制备可生物降解多嵌段共聚物P(LLA-mb-BSA)。重点考察了反应条件对扩链/偶联反应的影响,并对共聚物的链结构、热转变和力学性能进行了初步研究。该法简便高效,可制得高分子量的多嵌段共聚物。P(LLA-mb-BSA)多嵌段共聚物的软、硬段不相容,PLLA硬段保持较好的结晶性,而软段当分子量较低时接近无定型结构,其力学性能可由组成在较大的范围内进行调节。     

PBSu/PBAu嵌段聚酯酰脲共聚物的合成及流变性能

以羟基或氨基封端的丁二酸-丁二醇-尿素(Poly(butylene-succinate-urea),PBSu)聚酯酰脲共聚物与己二酸-丁二醇-尿素(Poly(butyleneadipate-urea),PBAu)聚酯酰脲共聚物为预聚物,借助甲苯-2,4-二异氰酸酯(Toluene-2,4-diisocyanate,TDI)对两种预聚物进行扩链反应,得到一种新的含PBSu和PBAu链段的可降解嵌段聚酯酰脲共聚物(PBSu-b-PBAu)。改变扩链时间、扩链温度、扩链剂含量进行了该嵌段共聚物的合成实验,并采用单因素选择法得到TDI扩链合成嵌段共聚物的最佳工艺条件。通过GPC、旋转流变仪、毛细管流变仪测定了最佳工艺条件下合成的不同进料比的嵌段共聚物的分子量和流变性能,结果表明含PBSu和PBAu链段的可降解嵌段聚酯酰脲共聚物具有比PBSu和PBAu更高的黏度和更好的弹性效应。     

含PBSu和PBAu链段可降解聚酯酰脲的合成及性能研究

以丁二酸-丁二醇-尿素(PBSu)聚酯酰脲共聚物与己二酸-丁二醇-尿素(PBAu)聚酯酰脲共聚物为预聚物,甲苯-2,4-二异氰酸酯(TDI)为扩链剂,通过熔融共聚成功地制备了可降解聚酯酰脲嵌段共聚物(PBSu-co-PBAu)。采用核磁共振氢谱(1HNMR)、热重分析仪(TG)、差示扫描量热仪(DSC)、X射线衍射仪(XRD)、万能拉力试验机以及水降解测试表征了共聚物的结构与性能。研究发现,随着PBAu含量的增加,嵌段共聚物塑性提高。合成得到的嵌段共聚物具有优异的热稳定性能和良好的生物降解性能,且具有比均聚物PBSu和PBAu以及未改性的聚酯PBS和PBA更好的拉伸性能。此外,还可以通过改变PBSu和PBAu的进料比,对材料的热性能、降解性能和力学性能进行一定范围的调节。     

长链支化PCL-b-PLLA共聚物共混改性聚乳酸的制备及性能

合成了一种长链支化聚己内酯-聚乳酸嵌段共聚物(LB-PCL-b-PLLA),通过熔融共混用于改性聚乳酸(PLA),并通过吹塑制备了改性PLA薄膜.利用长链支化聚己内酯嵌段的链缠结作用和聚乳酸嵌段与基体的共结晶作用,在改性PLA内部构建了类似化学交联的物理交联网络,同时实现了材料的增韧和熔体强度提升.实验结果表明,在仅添...     

新型嵌段聚氨酯和聚氨酯脲的性质研究

基于不同分子量的环氧乙烷－四氢呋喃共聚醚、异佛尔酮二异氰酸酯和扩链剂１，４－二醇／乙二胺等合成了一系列嵌段聚氨酯／嵌段聚氨酯脲，通过拉伸实验、差示扫描量热和Ｘ－ＲＡＹ衍射等对其结构和性质进行了研究。     

主链含磷的聚对苯二甲酸丙二醇酯嵌段共聚物的制备及性能

通过酯交换反应和熔融缩聚法制备了系列主链含磷的聚对苯二甲酸丙二醇酯(PTT)的多嵌段共聚物,并对其化学结构、相对分子质量、热稳定性、阻燃和力学性能进行了表征。结果表明,嵌段共聚酯具有膨胀型阻燃特性,随着主链中磷含量的增加,嵌段共聚酯初始分解温度降低,但残炭量和极限氧指数逐渐增加,含磷组分引入到大分子链提高了共聚酯的阻燃性能。由于共聚物相对分子质量的下降,阻燃共聚酯的拉伸强度和冲击强度均随着磷含量的增加而降低。     

含立构复合晶体的聚己内酯形状记忆弹性体的制备及性能

以聚己内酯(PCL)、左旋丙交酯(LLA)、右旋丙交酯(DLA)为原料,以辛酸亚锡(Sn(Oct)_2)为催化剂,合成了不同LA含量的P(LLA-b-CL)和P(DLA-b-CL)嵌段共聚物。用凝胶渗透色谱、核磁共振等研究了嵌段共聚物的组成与结构。将2种嵌段共聚物按一定比例溶液共混,并通过流延法得到PCL基形状记忆弹性体薄膜,研究了其结晶性能、晶体形态、力学性能及形状记忆性能。结果表明,随LA添加量增大,弹性体薄膜中的PLLA与PDLA形成的立构复合(SC)晶体结晶度增大;同时,PLA非晶区含量提高,70℃拉伸时PLA链段产生滑移,形状回复率降低。因此,弹性体中SC晶体的结晶度越高,形状回复率越高,形状回复率最佳可达93.54%。     

Synthesis and characterization of novel biodegradable pentablock copolymers from L‐lactide,p‐dioxanone and poly (ethylene glycol)

ABCBA type pentablock copolymers, in which the A, B and C blocks are poly (p‐Dioxanone) (PPDO), poly (L‐Lactide) (PLLA), and polyethylene glycol (PEG), respectively, were synthesized via a two‐step ring‐opening polymerization in bulk using stannous octoate as the catalyst. PLA‐b‐PEG‐b‐PLA Triblock copolymer was synthesized at first and then p‐Dioxanone monomers as the other blocks were added to it. In the first step, poly ethylene glycol and, in the second step, triblock copolymer acts as the macro initiator. The obtained copolymers were identified by ?1&/sup;H&/I;, ?13&/sup;CNMR&/I; and IR&/I; spectroscopy. The intrinsic viscosity of copolymers was measured in chloroform/phenol (3/1 v/w) solution. The thermal properties, such as melting point, melting enthalpy and crystallinity, were studied. From the results of differential scanning calorimetry and thermal gravimetric analysis, it was observed that the PPDO blocks show similar crystallization behavior like homopolymer and also melting temperature of two PPDO end blocks raise with an increase in DON content in copolymer.     

酰胺1010—b—己内酯多嵌段共聚物的合成与表征

羧基封端的酰胺１０１０预聚的与羟基封端的己内酯预聚物，在催化剂作用下直接进行酯化反应，产物用乙醇抽提，乙醇可溶物和不溶物经ＮＭＲ质子谱，ＦＴ－ＩＲ谱及元素分析，结果表明，生成了酰胺１０１０－ｂ－己内酯多嵌段共聚物。采用的酰胺１０１０预取物和己内酯预聚物同样分别有３种分子量，即Ｍｎ＝１０００，２０００和３０００。两种预聚物不同分子量的组合，合成得到了一系列不同硬，软链段含量的酰胺１０１０－ｂ－己内酯     

多嵌段共聚物的ATRP合成及表征

采用末端功能化的聚(二甲基硅氧烷)大分子(Br-PDMS-Br)为引发剂,CuCl为催化荆,2,2'-联吡啶(bpy)为配体,通过原子转移自由基聚合(ATRP)法,合成出结构明确的多嵌段共聚物聚甲基丙烯酸丁酯-b-聚二甲基硅氧烷-b-聚甲基丙烯酸丁酯和聚苯乙烯-b-聚甲基丙烯酸丁酯-b-聚二甲基硅氧烷-b-聚甲基丙烯酸...     

Dye-terminated, hyperbranched polytruxenes and polytruxene-block-polythiophene multiblock copolymers made in an "AB2 + A" approach

Novel dye-terminated, hyperbranched polytruxenes and polytruxene-block-polythiophene multiblock copolymers have been synthesized in a simple "AB(2) + A" approach. Photoexcitation into the higher energy polytruxene absorption band results in an efficient excitation energy transfer to the peripheral dye or polythiophene blocks.     

含聚氧乙烯嵌段的二元多嵌段共聚物的合成和性能

用甲苯二异氰酸酯将聚乙二醇及聚丙二醇或遥爪羟基聚苯乙烯偶联成多嵌段共聚物。研究了共聚条件及纯共聚物的表征。这两种共聚均具有良好的乳化性和一定的结晶度,与LiClO_4的络合物有颇高的室温导电率。第一种共聚物有一定的强度和弹性。     

聚乳酸嵌段共聚物的制备及扩链研究

为了获得性能更优良的聚乳酸材料,以乳酸、ε-己内酯、丁二酸酐为原料,采用梯度升温法合成了聚乳酸嵌段共聚物,用IPDI对其扩链.采用乌氏黏度法、FT-IR、1H-NMR、TGA及XRD等手段对产物进行了表征.FT-IR和1H-NMR测试结果显示,预期的聚乳酸嵌段共聚物成功合成;几种聚合方法中,以先合成端羟基活性低聚物P(...     

Fabrication of hydrophilic paclitaxel-loaded PLA-PEG-PLA microparticles via SEDS process

In this work, chemically bonded poly(D, L-lactide)-polyethylene glycol-poly(D, L-lactide) (PLA-PEG-PLA) triblock copolymers with various PEG contents and PLA homopolymer were synthesized via melt polymerization, and were confirmed by FTIR and ¹H-NMR results. The molecular weight and polydispersity of the synthesized PLA and PLA-PEG-PLA copolymers were investigated by gel permeation chromatography. Hydrophilicity of the copolymers was identified by contact angle measurement. PLA-PEG-PLA and PLA microparticles loaded with and without PTX were then produced via solution enhanced dispersion by supercritical CO₂ (SEDS) process. The effect of the PEG content on the particle size distribution, morphology, drug load, and encapsulation efficiency of the fabricated microparticles was also studied. Results indicate that PLA and PLA-PEG-PLA microparticles all exhibit sphere-like shape with smooth surface, when PEG content is relatively low. The produced microparticles have narrow particle size distributions and small particle sizes. The drug load and encapsulation efficiency of the produced microparticles decreases with higher PEG content in the copolymer matrix. Moreover, high hydrophilicity is found when PEG is chemically attached to originally hydrophobic PLA, providing the produced drug-loaded microparticles with high hydrophilicity, biocompatibility, and prolonged circulation time, which are considered of vital importance for vessel-circulating drug delivery system.     

聚乳酸-聚丁二酸丁二醇酯嵌段共聚体系对聚乳酸熔体流变性能的影响

采用未封端的聚乳酸(PLA1)和聚丁二酸丁二醇酯(PBS)通过大分子链末端直接脱水酯化反应制备聚乳酸-聚丁二酸丁二醇酯嵌段共聚体系(LB),并对比研究LB体系及纯PBS两种改性剂对封端聚乳酸(PLA)熔体流变性能的影响。流变测试结果证明,LB或PBS的添加均使PLA的储能模量有较明显的提高。但当改性剂的含量相同时,LB对PLA熔体流变性能的提高幅度明显高于PBS,这可能是因为在LB共聚体系中除传统的"海岛"结构外还形成了新的PLA1-PBS"核壳"结构。     

Synthesis of multiblock thermoplastic elastomers based on biodegradable poly (lactic acid) and polycaprolactone

A new biodegradable (AB)_n type of multiblock copolymers derived from poly (ε-caprolactone) (PCL) and poly (lactic acid) (PLA) was prepared via the method of the chain extending reaction among PCL oligomers, PLA oligomers and hexamethylene diisocyanate (HDI). Fourier transform infrared spectra (FTIR), ¹H NMR, thermal gravity analysis (TGA) and derivative thermograms (DTG) were used to characterize the copolymers and the results showed that PCL and PLA were coupled by the reaction between –NCO groups and terminal –OH and –COOH groups of PCL and PLA, respectively. The material displayed enhanced mechanical properties: Young's modulus was as low as 2.7 ± 0.7 MPa and elongation at break value was above 790% at the composition of PCL/PLA = 80/20 (w/w). Moreover, according to SEM micrographs interfacial adhesion of the composites was improved. Thermal degradation temperature of the composites was higher than PLA but was lower than PCL, which is an advantage for industry process.     

Modification of nylon-6 with poly (m-phenylene isophthalamide) via MDI as a chain extender

Reinforcement of flexible nylon-6 by using poly (m-phenylene isophthalamide) PmIA (Nomex) using (MDI) 4,4-diphenylene methane diisocyanate as a chain extender was studied. Observation by scanning electron microscopy showed that the multiblock copolymer had a homogeneous texture. From the differential scanning calorimetry measurements, the multiblock copolymers were shown to have only one melting point, T _m, which is higher than that of nylon-6. The wide-angle X-ray diffraction pattern shows that nylon-6 has two diffraction peaks at 2=20° and 23.8°. However, the multiblock copolymer has only one peak at 2=20°, indicating a different crystal structure of multiblock copolymers. The copolymers appear to have a significant reinforcing effect on the mechanical properties.