共查询到19条相似文献,搜索用时 156 毫秒
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温敏性PCL-PEG-PCL水凝胶的合成、表征及蛋白药物释放 总被引:2,自引:0,他引:2
考察了温敏性PCL-PEG-PCL水凝胶中聚乙二醇(PEG)及聚己内酯(PCL)不同嵌段组成对其溶胶-凝胶相转变温度以及亲水性药物(牛血清白蛋白, BSA)释放速率的影响. 采用开环聚合法, 以辛酸亚锡为催化剂、PEG1500/PEG1000为引发剂, 与己内酯单体发生开环共聚, 合成了一系列具有不同PEG和PCL嵌段长度的PCL-PEG-PCL型三嵌段共聚物. 通过核磁共振氢谱及凝胶渗透色谱对其组成、结构及分子量进行了表征. 共聚物的溶胶-凝胶相变温度由翻转试管法测定. 利用透射电镜、核磁共振氢谱及荧光探针技术证实了该材料在水溶液中胶束的形成. 以BSA为模型蛋白药物, 制备载药水凝胶, 利用microBCA法测定药物在释放介质中的浓度, 研究其体外释放行为. 实验结果表明, 共聚物的溶胶-凝胶相变温度与PCL及PEG嵌段长度紧密相关, 即在给定共聚物浓度情况下, 固定PEG嵌段长度而增加PCL嵌段长度, 会导致相变温度降低; 而固定PCL嵌段长度而增加PEG嵌段长度, 其相变温度相应升高. 水凝胶中蛋白药物的释放速率与疏水的PCL嵌段长度无关, 而与亲水的PEG嵌段长度密切相关, 即PEG嵌段越长, 蛋白药物释放越快. 相似文献
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合成了系列聚右旋乳酸(PDLA)嵌段重量分率(fw=0~0.61)的窄分子量分布聚苯乙烯-b-聚右旋乳酸二嵌段共聚物(PS-b-PDLA).运用温度调制示差扫描热分析仪(TMDSC)和热台偏振光显微镜(POM)等研究手段,对制备所得的结晶性二嵌段共聚物的热性能、结晶速率与结晶形貌等进行了研究.研究结果表明,与聚右旋乳酸均聚物相比,随着PS-b-PDLA中结晶性PDLA嵌段重量分率fw减少,无定形聚苯乙烯嵌段(PS)对PDLA嵌段链段的结晶抑制作用增强,PS-b-PDLA的热结晶性能与结晶形貌发生显著变化;相对于PDLA均聚物,PS-b-PDLA的冷结晶温度(Tcc)和结晶平衡熔点(Tm0)分别下降14℃和38℃,球晶生长速率明显降低.在无定形PS嵌段链段的玻璃化温度(Tg)附近,二嵌段PS-b-PDLA的结晶行为出现拐点,揭示PS嵌段由于相分离所形成纳米微相空间对PS-b-PDLA中PDLA链段的结晶产生影响,并且该影响作用程度与PDLA嵌段的重量分率fw和结晶温度(Tc)相关。 相似文献
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聚对苯二甲酸丁二酯-聚四亚甲基醚多嵌段共聚物的研究 总被引:5,自引:1,他引:5
合成了硬段含量和软段分子量不同的聚对苯二甲酸丁二酯-聚四亚甲基醚(PBT-PTMG)多嵌段共聚物。研究了硬段含量和软段分子量对嵌段共聚合过程的影响。当软段分子量较大、硬段含量较高时,在嵌段共缩聚过程中有均聚物伴生。当软段分子量在2000左右,硬段含量在20%左右时,基本上不生成均聚物。硬段重量含量为 20%的低硬段 PBT-PTMG多嵌段共聚物是结晶的。由它纺成的弹体纤维有良好的力学性能和弹性回复。热处理能改进纤维的弹性回复。 相似文献
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以三枝化低不饱和度聚环氧丙烷(PPO)引发D-丙交酯(D-LA)逐步开环聚合, 合成了三枝化聚环氧丙烷-聚右旋乳酸(PPO-PDLA)共聚物. 用辛酸亚锡Sn(Oct)2与PPO-PDLA端羟基反应进行Sn(Oct)封端, 制备了三枝化PPO-PDLA-Sn(Oct)预聚物. 再于130 ℃下, 以其作为大分子引发剂与L-丙交酯(L-LA)开环聚合, 合成了分子量>105的三枝化PPO-PDLA-PLLA嵌段共聚物. 活性端基的引入, 降低了聚合反应温度, 从而降低了聚合中的酯交换或热降解反应发生的概率. 实现了高分子量PPO-PDLA-PLLA嵌段共聚物的合成. 结构测试结果表明, 合成的嵌段共聚物具有分子结构易控及立构规整度高等特点. 在结晶-熔融-再结晶重复热处理下, 三枝化PPO-PDLA-PLLA嵌段共聚物仅发生立构复合聚乳酸结晶, 且结晶能力稳定. 相似文献
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首先合成双端羟基的聚对二氧环己酮预聚物(PPDO)和双端羧基的聚乙二醇预聚物(PEG),然后以丁二酸酐/二环己基碳二亚胺(DCC)将PPDO与PEG偶联共聚,得到PPDO/PEG多嵌段共聚物.通过1H-NMR和GPC表征了聚合物的结构和分子量.采用差示扫描量热法(DSC)和热重分析(TGA)研究了共聚物的结晶性能和热稳定性.用透析法制备了共聚物纳米粒子,并用动态光散射(DLS)表征了共聚物纳米粒子的粒径及分散度,结果表明,随着共聚物亲水链段PEG含量的增加,其纳米粒子更易形成,粒子粒径随共聚物分子量增大而增大. 相似文献
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聚己内酯,聚乙二醇及其嵌段物的结晶行为高家武,段跃新,王身国,邱波(北京航空航天大学材料科学与工程系北京100083)(中国科学院化学研究所北京)关键词聚己内酯,聚乙二醇,嵌段共聚物,结晶度,结晶动力学聚己内酯(PCL)作为生物降解材料,无毒、无副作... 相似文献
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Anjie Dong Yinglei Zhai Li Xiao Haiying Qi Qi Tian Liandong Deng Ruiwei Guo 《Journal of Polymer Science.Polymer Physics》2010,48(5):503-508
The poly(ethylene glycol)/poly(2‐(N,N‐dimethylamino)ethyl methacrylate) (PEG/PDMAEMA) double hydrophilic block copolymers were synthesized by atom transfer radical polymerization using mPEG‐Br or Br‐PEG‐Br as macroinitiators. The narrow molecular weight distribution of PEG/PDMAEMA block copolymers was identified by gel permeation chromatography results. The thermosensitivity of PEG/PDMAEMA block copolymers in aqueous solution was revealed to depend significantly on pH, ionic strength, chain structure, and concentration of the block copolymers. By optimizing these factors, the cloud point temperature of PEG/PDMAEMA block copolymers can be limited within body temperature range (30–37 °C), which suggests that PEG/PDMAEMA block copolymers could be a good candidate for drug delivery systems. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 503–508, 2010 相似文献
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Qin Lin Serkan Unal Ann R. Fornof Yuping Wei Huimin Li R. Scott Armentrout Timothy E. Long 《Macromolecular Symposia》2003,199(1):163-172
Linear and branched poly(ethylene terephthalate) (PET) copolymers with polyethylene glycol) (PEG) methyl ether (700 or 2000 g/mol) end groups were synthesized using conventional melt polymerization. DSC analysis demonstrated that low levels of PEG end groups accelerated PET crystallization. The incorporated PEG end groups also decreased the crystallization temperature of PET dramatically, and copolymers with a high content of PEG (>17.6 wt%) were able to crystallize at room temperature. Rheological analysis demonstrated that the presence of PEG end groups effectively decreased the melt viscosities and facilitated melt processing. XPS and ATR-FTIR revealed that the PEG end groups tended to aggregate on the surface, and the surface of compression molded films containing 34.0 wt% PEG were PEG rich (85 wt% PEG). PEG end-capped PET (34.0 wt% PEG) and PET films were immersed into a fibrinogen solution (0.7 mg/mL BSA) for 72 h to investigate the propensity for protein adhesion. XPS demonstrated that the concentration of nitrogen (1.05%) on the surface of PEG endcapped PET film was statistically lower than PET (7.67%). SEM analysis was consistent with XPS results, and revealed the presence of adsorbed protein on the surface of PET films. 相似文献
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Ingrid W. Velthoen Edze J. Tijsma Pieter J. Dijkstra Jan Feijen 《Macromolecular Symposia》2008,272(1):13-27
Summary: Branched poly(L -lactide)-poly(ethylene glycol) (PLLA-PEG) block copolymers were synthesized from trifunctional PLLA and amine functionalized methoxy poly(ethylene glycol)s. The copolymers in water formed hydrogels that showed thermo-responsive behavior. The hydrogels underwent a gel to sol transition with increasing temperature as determined with the vial tilting method and oscillatory rheology. For all copolymers, the transition temperature increased with increasing copolymer concentration. The transition temperature of corresponding branched copolymers also increased with increasing PEG molecular weight, and surprisingly decreased with increasing molecular weight of the PLLA branches. In general, the gel-sol transition is explained by disruption of micellar or aggregate interactions because of partial dehydration and shrinkage of the PEG chains. An increase in the molecular weight of the PLLA branches led to the formation of micelles and aggregates as observed with DLS at low concentrations. It is speculated that the non-uniform size distribution and possible crystallization of longer PLLA blocks may have a negative effect on the formation of micellar packing upon gelation, allowing the disruption of micellar or aggregate interactions to occur at lower temperatures. The transition temperature of the gels could be tuned closely to body temperature by varying the concentration of the solution or the molecular weight of the PEG block and the PLLA blocks, which implies that these polymers may be used as injectable systems for in-situ gel formation. 相似文献
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利用差示扫描量热法(DSC)、偏光显微镜(POM)以及傅里叶变换红外(FTIR)光谱研究了一种超支化聚酯(HBP)对聚乙二醇(PEG)非等温结晶行为的影响,用Ozawa法、Jeziorny法和莫志深法对非等温结晶动力学进行了分析.结果表明:PEG和HBP/PEG的非等温结晶过程可用Ozawa和莫志深动力学方程描述,与Jeziorny动力学方程不符;超支化聚酯的加入改变了PEG的结晶成核和生长机理,对PEG的结晶有一定的延缓作用.超支化聚酯中的羰基与PEG的端羟基形成的氢键以及超支化聚酯自身较大的分子体积和高度支化的结构所导致的位阻效应是超支化聚酯延缓PEG结晶的主要原因. 相似文献
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Abstract Macro photoinitiators possessing polyethylene glycol(PEG) segments were used for radical polymerization of acrylamide(AAm) to yield high molecular weight block copolymers (PAAm-b-PEG-b-PAAm) composed of PEG and polyacrylamide(PAAm) as the inner segment and outer segment respectively. The block copolymers were used as flocculates to clear a saturated borax solution prepared from tincal concentrate and showed good flocculating properties. 相似文献
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Poly(trimethylene terephthalate)/polyethylene glycol (PTT/PEG) copolymers, with PEG content ranging from 27.2 to 47.4 wt%, were synthesized by melt copolycondensation. Wide-Angle X-ray diffractometer revealed that all copolymers had the same crystal structure of homo-PTT at room temperature. All copolymers could form ring-banded spherulites, and band spacing increased with increasing PEG content at a given crystallization temperature. Nonisothermal crystallization morphology of copolymers was greatly influenced by cooling rate. When the cooling rate was 2.5 °C/min or lower, banded patterns were absent, whereas when the cooling rate was 20 °C/min or higher, a novel crystal morphology composed of non-banded spherulites (central part) and ring-banded spherulites with decreasing band spacing along the radial growth direction was observed. Moreover, the size of the non-banded spherulitic part decreased with increasing cooling rate. Finally, the nonisothermal crystallization kinetics of copolymers were analyzed and only the Mo method was satisfactory to accurately describe this system. 相似文献
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Crystalline-crystalline poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly (ethylene glycol) (PEG) block copolymers (PHEGs) were synthesized by telechelic hydroxylated PHBV2000 and PEG with different number-average molecular weights. The synthesized PHEGs were analyzed using gel permeation chromatography and proton nuclear magnetic resonance. The cooling curves of the differential scanning calorimetry showed that the range of the melt-crystallization temperature of the PEG and PHBV blocks in the PHEGs partially overlapped. The spherulite of each PEG block and each PHBV block in the PHEGs crystallizes individually, but nucleated in the same site to form a concentric spherulite. The observations of the hot-stage polarized microscope (HSPM) showed that the first spherulite growth acted as a template for the later spherulite growth in the PHBV-b-PEG concentric spherulite. The spherulite growth rate of individual spherulite from the PEG block and PHBV block in PHEGs depends on the crystallization environment. The evolution of concentric spherulites in PHEGs at different crystallization conditions was studied in this study. 相似文献