不同结晶度聚乳酸膜降解性的研究

结晶度是影响可降解聚合物降解性的重要指标之一.作者利用三氯甲烷和其它有机溶剂混合来溶解聚乳酸,制备出聚乳酸的溶剂膜并比较了其降解性.实验中采用三氯甲烷为溶剂先制备出5%的聚乳酸溶液,待其完全溶解后再分别加入5%(质量分数)的乙醇、乙酸乙酯、己烷、四氢呋喃、苯和甲苯.DSC测试结果表明,不同混合溶剂制备的聚乳酸溶剂膜具有不同的结晶度,膜的结晶度不但受溶剂种类的影响,同时也与其添加的量有关,此外结晶度与其降解性有一定的关系.     

不同分子量超高脱乙酰度壳聚度糖的制备

将甲壳素分别在含硼氢化钠的氢氧化钠-正戊醇中和氢氧化钠-水中进行脱乙酰反应,再将得到的壳聚糖用过氧化氢-水反应体系降解,制得不同分子量的超高脱乙酰度壳聚糖.在氢氧化钠-正戊醇中制备的壳聚糖分子量介于24万和35万之间,在氢氧化钠-水中制备的壳聚糖分子量介于81万和100万之间.实验结果表明:在氢氧化钠-正戊醇体系中反应5 h或在氢氧化钠-水体系中反应6 h所制备壳聚糖的脱乙酰度均达98%以上,在脱乙酰反应中,延长反应时间脱乙酰度增大;采用过氧化氢-水反应体系降解壳聚糖时,影响壳聚糖分子量的因素包括过氧化氢与壳聚糖的投料比、反应温度及反应时间,而过氧化氢与壳聚糖的投料比是主要的影响因素.改变这些影响因素,可制备出分子量介于3.2万和56万之间的壳聚糖.     

壳聚糖膜的制备及性能研究

壳聚糖具有良好的生物相容及生物降解性,在医药、环境、印染等领域有较多应用。本文利用壳聚糖的优良成膜性能制备了系列壳聚糖膜,同时对壳聚糖膜的吸水性、耐酸性、耐盐性、透光率、强度等性能行了研究。实验表明：壳聚糖膜的拉伸强度在所研究的浓度范围内随着铸膜液浓度的增大呈现降低趋势。经戊二醛交联后膜的尺寸稳定性能、耐化学品性能以及力学性能均有所提高。壳聚糖膜的透光度与壳聚糖浓度、交联剂加入量有较大关系。     

壳聚糖与己内酯接枝材料膜的制备及性能研究

将己内酯低聚物成功地接枝到壳聚糖分子上，制备出一种新型的壳聚糖材料膜，用化学分析及红外光谱表征结构，并测试了相关性能，结果表明，在一定温度及催化剂下，已内酯低聚物与壳聚糖分子接枝混杂，形成的材料膜改善了壳聚糖膜的脆性，并显示出良好的降解性。     

壳聚糖的超声波降解及最佳工艺研究

以天然大分子量壳聚糖为原料,利用超声波降解法制备低聚壳聚糖,并通过单因素实验研究盐酸质量分数、降解温度、超声功率和超声时间对超声波降解壳聚糖的影响,采用正交试验设计确定制备分子量小于1万的低聚壳聚糖的最佳降解条件.超声波降解壳聚糖的最佳降解条件为:盐酸质量分数3％、降解温度65℃、超声功率500 W、超声时间180 m...     

微波催化法制备壳聚糖及其膜性能研究

采用微波催化法制备了具有不同分子量及脱乙酰度的壳聚糖,探讨了反应时间对壳聚糖分子量和脱乙酰度的影响,并考察了壳聚糖分子量对其膜结晶性能、透气性能和拉伸性能的影响．结果表明：壳聚糖膜的结晶度随分子量的增加而降低,随成膜时间的延长而增加;壳聚糖膜的透氧气和二氧化碳性能均随着其分子量的增大而减小;壳聚糖膜拉伸强度随其分子量的增大而减小,其断裂伸长率随分子量增大而有所增加．     

微波催化法制备壳聚糖及其膜性能研究

采用微波催化法制备了具有不同分子量及脱乙酰度的壳聚糖,探讨了反应时间对壳聚糖分子量和脱乙酰度的影响,并考察了壳聚糖分子量对其膜结晶性能、透气性能和拉伸性能的影响.结果表明:壳聚糖膜的结晶度随分子量的增加而降低,随成膜时间的延长而增加;壳聚糖膜的透氧气和二氧化碳性能均随着其分子量的增大而减小;壳聚糖膜拉伸强度随其分子量的增大而减小,其断裂伸长率随分子量增大而有所增加.     

聚乳酸超细纤维膜的制备及降解性能研究

通过静电纺丝法制备了不同相对分子质量的聚乳酸和聚乳酸/羟基磷灰石(PLLA/HA)复合纤维膜。对纤维膜的微观结构、热性能及体外降解进行了分析。结果表明:实验中所制备的PLLA纤维膜具有珠串的微结构,经过体外降解后变成了多孔结构,该结构有利于细胞的吸附;PLLA/HA纤维复合膜中羟基磷灰石抑制了PLLA降解过程中的自催化作用,减缓了降解速率。     

过氧化氢制备壳低聚糖及分子量和其分布的研究

在弱酸性备件下，采用过氧化氢法降解壳聚糖。研究了降解过程中潭度、时间和过氧化氢用量对壳低聚糖分子量及其分布变化的影响。结果表明，反应温度的升高，反应时间的延长以及过氧化氢用量的增加都有利于壳聚糖分子量的降低。分子量分布随降解温度升高变宽，而反应时间的延长，过氧化氢用量的增加，壳低聚糖的分子量分布（PD）变窄。     

光交联壳聚糖／聚乙烯醇共混膜的制备与性能

将壳聚糖与感光性物质混合制成感光性壳聚糖，再与聚乙烯醇按一定比例共混、成膜并进行光交联，制备了系列壳聚糖（CTS）／聚乙烯醇（PVA）光交联共混膜，并对共混膜的结构和性能进行比较，结果表明：重氮树脂系列CTS／PVA光交联共混膜性能优于CTS／PVA共混膜，且重氮树脂系列CTS／PVA光联共混膜有其独特的表面形貌，孔结构的大小及形态与共混膜中CTS／PVA的比例、重氮树脂的含量有关。     

BIODEGRADATION AND MECHANICAL PROPERTIES OF HYDROXYAPATITE/POLY-DL-LACTIDE COMPOSITES FOR FRACTURE FIXATION

The biodegradation and mechanical properties of self-designed hydroxyapatite/poly-DL-lactide (HA/PDLLA) compositites -were investigated in vitro and invio. In vitro, the specimens of HA/PDLLA and unfilled PDLLA -with similar molecular weights were immersed in phosphate-buffered saline. Ageing of the various devices were monitored by measuring molecular weight,water absorption, weight loss, PH, mechanical strengths and mi-crostructural changes. The follow-up times were 2, 4 , 6 , 8, 10 and 12 weeks. In vivo, a transverse transcondylar osteotomy of the distal femur was fixed with a HA/PDLLA rod (diameter, 4. 5mm;length, 30-40mm). The follow-up times were 3. 6 and 12 weeks. Roentgenographic, histologic, and biomechanical studies were carried out. The results show that the HA/PDLLA composities have higher mechanical strength and slower degradation than that of the unfilled PDLLA and that of all osteotomies unite within six weeks without delay. Consequently, the HA/PDLLA composites possess sufficient mechani     

Preparation and Charactcrization of a Novel PDLLA/Chondroitin Sulfate/Chitosan Asymmetry Film

A novel bioactive and bioresorbable asymmetry film was prepared,The PDLLA membrane was activated by 1,6-hexanediamine to obtain a stable positive charge surface.Chondroitin sulfate and chitosan were then deposited on activated PDLLA membrane via layer-by-layer(LBL)electro-static assembly (ESA)technique.The deposition process was monitored by UV-Vis absorbance spectroscopy.The composite membrane was frozen lyophilized to form the asymmetry film and characterized by attenuated total reflectic (ATR)-FT-IR,XPS and SEM.The experimental results show that a stable 1,6-hexanediamme layer on PDLLA substrate based on the aminolysis of the polyester and the layer thickness increase linearly first with the increase of the deposited layers,and then increases slowly due to the layer interpenetration.The test results of ATR-FT- IR and SEM show the asymmetry film is modified uniformly with a dense inner layer and a porous sponge outer layer.     

Preparation and Degradation Characteristics of Poly （d,l-lactide） Composite Films

PDLLA/CHI/β-TCP/NGF composite films were prepared by a solvent evaporation method. The degradation characteristics of the poly （d, l-lactide） composite films were studied in vitro and in vivo. The acidity produced by poly （d, l-lactide） materials was not obvious. Adding chitosan and β-TCP can relieve the acidity problem and improve strength performance of films. The NGF has influences on the degradation characteristics of films. It is verified that PDLLA/CHI/β-TCP/NGF composite films prepared by solvent evaporation method have excellent degradation characteristics. It can be used as a perfect biomaterial for repairing nerve injuries.     

Preparation and Characterization of a Novel PDLLA/ Chondroitin Sulfate/Chitosan Asymmetry Film

A novel bioactive and bioresorbable asymmetry film was prepared. The PDLLA membrane was activated by 1, 6-hexanediamine to obtain a stable positive charge surface. Chondroitin sulfate and chitosan were then deposited on activated PDLLA membrane via layer-by-layer （LBL） electro-static assembly （ESA） technique. The deposition process was monitored by UV-Vis absorbance spectroscopy. The composite membrane was frozen lyophilized to form the asymmetry film and characterized by attenuated total reflectic （ATR）-FT-IR, XPS and SEM. The experimental results show that a stable 1, 6-hexanediamine layer on PDLLA substrate based on the aminolysis of the polyester and the layer thickness increase linearly first with the increase of the deposited layers, and then increases slowly due to the layer interpenetration. The test results of ATR-FT- IR and SEM show the asymmetry film is modified uniformly with a dense inner layer and a porous sponge outer tayer.     

In vitro Degradation of Butanediamine-Grafted Poly（DL-Lactic acids）

The degradation of butanediamine-grafted poly（DL-lactic acid） polymers （BDPLAs） in vitro together with PDLLA and maleic anhydride-grafted poly（DL-lactic acid） polymers （MPLAs） was investigated by observation of the changes of the pH value of incubation media, and weight loss ratio during degradation duration of 12 weeks. The results reveal that the acidity of PDLLA degradation products was weakened or neutralized by grafting butanediamine onto PDLLA. A uniform degradation of BDPLAs was observed in comparison with an acidity-induced auto-accelerating degradation featured by PDLLA and MPLAs. The biodegradation behaviors of BDPLAs can be adjusted by controlling the content of BDA. BDPLAs might be a new derivative of PDLLA-based biodegradable materials for medical applications without acidity-caused irritations and acidity-induced auto-accelerating degradation behavior as that of PDLLA.     

壳聚糖膜的制备及其表面浸润性

采用流延法,通过调节壳聚糖溶液的质量分数制备表面结构不同的壳聚糖膜,并通过扫描电子显微镜和静态接触角测定仪对膜表面形貌及浸润性进行了研究。结果表明,壳聚糖溶液的质量分数是壳聚糖膜表面形貌的重要影响因素。在壳聚糖溶液的质量分数由2%增至8%条件下,所制备的壳聚糖膜的表面结构从有较强立体层次感的簇状凸起逐渐变得层次感降低,纹路密集,并出现很多紧密排列的小颗粒;膜表面的浸润性发生细微变化,在空气中均表现为既亲水又亲油的特性,而在水中油滴的表面接触角平均高达150°以上,即达到超疏油性。     

PDLLA/HA/FK506复合神经导管的制备及体外降解性能

以聚乳酸（PDLLA）为基材、纳米羟基磷灰石（HA）为添加剂、加入免疫抑制剂FK506，用溶剂挥发法制备PDLLA／HA/FK506复合神经导管。通过观察复合导管在磷酸缓冲溶液中降解时pH值变化、质量损耗及材料微观形貌，研究了该复合导管的体外降解性能。结果表明：加入适量纳米羟基磷灰石可以改善聚乳酸降解的酸性问题并提高其力学强度。免疫抑制剂FK506的加入对导管材料的降解性能有一定的影响。PDLLA/HA／FK506复合神经导管具有良好的降解性能。     

低相对分子质量壳聚糖季铵盐碘络合物性质

壳聚糖（CTS）氧化降解得低相对分子质量壳聚糖（CTS’）,接入3-氯-2-羟丙基三甲基氯化铵（CTA）单体得低相对分子质量壳聚糖季铵化衍生物（CTS＇-CTA）．CTS＇-CTA与单质碘能生成稳定络合物（CTS＇-CTA-I2）．在络合物溶液中,络合物呈一定规则形态,粒径主要分布在1000nm左右．CTS＇-CTA-I2与壳聚糖和聚乙烯吡咯烷酮（PVP）混合制备凝胶薄膜（CTS-[CTS’-CTA-I2]-PVP）,扫描电子显微镜（SEM）显示碘络合物均匀地分布在凝胶薄膜上．CTS-[CTS＇-CTA-I2]-PVP凝胶薄膜对大肠杆菌和金黄色葡萄球菌的抑菌环直径均大于15mm,为高度敏感．     

辐射法降解壳聚糖对酵母菌的抑菌特性研究

采用辐射法对壳聚糖进行降解处理．通过酵母菌的抑菌实验验证0．2g/L的辐射壳聚糖具有明显的抑菌活性，并进一步对辐射前后的壳聚糖的分子量进行到定，初步探索了分子量的大小与抑菌作用的关系。