不同比例及旋光结构的MPEG-PLGA合成与性能研究

以乙交酯(GA)和两种不同旋光结构的丙交酯(LA)∶外消旋丙交酯(D,L-LA)和左旋丙交酯(L-LA)为原料,在聚乙二醇(PEG)引发下合成了一系列不同LA/GA摩尔比的聚乙二醇-聚丙交酯乙交酯(MPEG-PLGA)嵌段共聚物,并对其结构、结晶性、热性能和力学性能进行了分析测试。结果表明:由D,L-LA合成的共聚物均为非晶态,LA/GA的变化对其各方面性能影响较小;而L-LA合成的共聚物在LA/GA为75∶25时出现结晶性,90∶10时结晶度进一步增大,玻璃化转变温度及拉伸强度也随之明显提高。     

新型药物载体材料——端羟基聚(丙交酯-co-对二氧环己酮)的合成与表征

聚乳酸(PLA)作为药物载体材料存在因疏水性强而导致的药物释放速率难控以及在循环系统中停留时间短等问题.研究表明,在PLA中引入乙醇酸(GA)可提高材料降解速率,引入聚乙二醇(PEG)则可延长共聚物在循环系统中的停留时间.研究以丙交酯(LA)和对二氧环己酮(PDO)为主要原料,在辛酸亚锡-乙二醇共引发体系的存在下,通过熔融开环聚合制备出了端羟基聚(丙交酯-co-对二氧环己酮)(HO-P(LA-co-PDO)-OH).这种同时具有PLA、GA和EG结构单元的大分子二醇可望成为一种降解速率可控、在循环系统中停留时间可调的新型药物载体材料.采用DSC、~1H NMR、~(13)C NMR和GPC-MALLs等对其结构和热学性能进行了表征.分子量检测结果表明,HO-P(LA-co-PDO)-OH的分子量随原料中PDO/LA摩尔比的减小而增大.     

不同构型乳酸对乳酸-羟基乙酸直接熔融共聚产物的影响

分别以外消旋乳酸 (D ,L LA)和左旋乳酸 (L LA)为原料 ,与乙醇酸 (GA)直接熔融共聚 ,以 0 .5 %氯化亚锡为催化剂 ,在 16 5℃、70Pa下反应 10h ,合成了不同配比的系列生物降解高分子乳酸 乙醇酸共聚物 (PLGA)。用GPC、FTIR、1 HNMR、DSC、X 射线衍射等进行表征 ,发现原料乳酸 (LA)的构型对聚合物的Mw、Tg、结晶性、组成等产生影响。单体投料摩尔比LA GA =5 0 5 0时 ,D ,L PLGA的 [η]和Mw比L 型大。以D ,L LA为原料时 ,共聚物结构相对简单 ,共聚物性质易受GA链段控制。投料摩尔百分比LA(或GA)≥ 90 %时 ,共聚物易于结晶 ,以L LA为原料时更为明显。利用1 HNMR数据计算共聚物组成 ,发现GA组分含量高于其投料值 ,且D ,L PLGA中GA的组成高于L 型产物。根据上述实验事实 ,提出D ,L LA、L LA分别与GA共聚时 ,由于GA在共聚中反应速率比LA高 ,并且D ,L LA与L LA存在反应速率差异 ,故有不同反应机理。     

对二氧环己酮与丙交酯共聚反应的~1H-NMR分析

由对二氧环己酮（PDO）和丙交酯（LA）单体,在不同温度下合成了PDO-co-LA共聚物,采用核磁共振（1H-NMR）研究了共聚反应动力学和共聚物分子链结构,提出了一种链段平均序列长度的计算方法。结果显示,丙交酯在共聚反应中的聚合能力要比对二氧环己酮强;实验条件下LA/PDO投料物质的量比为2/3时,共聚物中PDO与L...     

聚乳酸-乙醇酸熔融共聚物的制备与性能研究

以乳酸（LA）、乙醇酸（GA）为单体，通过直接熔融共聚法合成可生物降解材料聚乳酸-乙醇酸（PLGA）共聚物．研究了聚合时间、催化剂种类、搅拌速度、单体配比等因素对聚合物特性粘数的影响。结果表明：乳酸LA/乙醇酸GA为1：1，反应时间10h，氯化亚锡为催化剂，搅拌速度为200f／min时聚合物特性粘数最大。同时对共聚物的结构和形貌进行了表征。     

纳米C60/C70对丙烯酸(酯)共聚物的抗紫外线老化改性作用

将纳米C60／C70直接引入到丙烯酸(酯)共聚物中，合成具有抗紫外线功能的C60／C70-丙烯酸(酯)共聚物。用共聚物配制清漆，测定了固化后漆膜在紫外光照射下的光泽．时间变化曲线。探讨了共聚物抗紫外线的机理。     

耐溶剂型半互穿网络膜的制备方法

采用原住聚合法。以光油和二丙烯酸正己酯为前驱物,通过在体系中添加经硅烷偶联剂KH-570改性的蚋米CaCO3／SiO2核-壳结构复合粒子．成功制备出聚丙烯酸酯／聚二丙烯酸正己酯-IPN(PA／PHDDA半-IPN)膜和聚丙烯酸酯／聚二丙烯酸正己酯／纳米拉子(PA／PHDDA／纳米粒子半-IPN)膜。所制备的半．IPN膜仍具有良好的透光率和光泽度．以乙醇和丙酮作为介质对两种半-IPN膜的耐溶剂性能进行考察的结果表明。半-IPN膜具有良好的抗溶剂性能;同时PA／PHDDA／纳米粒子半-IPN膜也具有更高的热稳定性能。     

纳米C60/C70-丙烯酸(酯) 共聚物的合成及性能

将纳米C60／C70与丙烯酸(酯)单体在引发剂作用下共聚，合成得到C60／C70-丙烯酸(酯)共聚物。对该共聚物的结构进行了红外光谱和荧光光谱分析，探讨了有富勒烯参与的聚合反应机理和共聚物结构。将该共聚物用有机胺中和成盐，使其水性化，制得水溶性纳米C60／C70-丙烯酸(酯)高分子成膜材料，对其成膜性能进行了分析测试。发现C60／C70对丙烯酸(酯)聚合物具有独特的成膜改性功能。     

MPEG-PLLGA多孔支架制备影响因素研究

采用热致相分离法制备了MPEG-PLLGA(单甲氧基聚乙二醇-聚左旋丙交酯乙交酯)多孔支架。讨论了丙交酯/乙交酯(LA/GA)配比、聚合物质量浓度、预冻温度等因素对支架的孔径、孔隙率和力学性能的影响。结果表明,当聚合物质量浓度为0.03g/mL时,不同n(LA)/n(GA)比的MPEG-PLLGA支架的孔形貌相差较大,而当聚合物质量浓度为0.04g/mL和0.05g/mL时,3种n(LA)/n(GA)比的MPEG-PLLGA支架的孔形貌和孔径没有明显差异,且在相同聚合物质量浓度下,随着n(LA)/n(GA)比升高,所得支架的压缩强度增大;随聚合物溶液质量浓度的提高,3种n(LA)/n(GA)比支架的孔隙率、孔径均呈变小趋势,压缩强度逐渐增大;随预冻温度的降低,所得支架的孔径、孔隙率逐渐变小,压缩强度逐渐增大。     

UV固化含氟聚丙烯酸酯的制备

以甲基丙烯酸十二氟庚酯、丙烯酸-2-乙基己酯、甲基丙烯酸羟乙酯、苯乙烯为聚合单体,偶氮二异丁腈为引发剂,通过溶液聚合制得了含氟羟基聚丙烯酸酯共聚物(PGHES),以含异氰酸酯的不饱和单体HIp与共聚物PGHES侧链上的羟基反应制得光敏性含氟聚丙烯酸酯(U-PGHES)。用傅立叶红外光谱(FT-IR)、核磁共振氢谱(1 H-NMR)表征聚合物结构;用凝胶渗透色谱(GPC)及差示扫描量热仪(DSC)表征聚合物分子量及玻璃化转变温度;用光学接触角测量仪测量了聚合物固化膜接触角并计算得到表面能。结果表明,固化膜表面能随U-PGHES中含氟量的增加而降低,当含氟量达到9%时,表面能降低趋缓。     

Preparation and humidity-sensing properties of nanostructured potassium tantalate thin films

Nanostructured potassium tantalate (KT) thin films are prepared using a sol–gel process and the humidity-sensing behaviors of the films are investigated. The films possessed nano-sized grains and nanoporous structure. The KT film annealed at 500 °C showed high humidity sensitivity with nearly three orders change in the resistance during the relative humidity variation from 20% to 90%. The humidity-sensing behaviors of the thin films with annealing temperature are discussed.     

Humidity sensing properties of nanostructured- bilayered potassium tantalate: Titania films

Nanostructured-bilayered potassium tantalate (KT): titania (TiO₂) films have been prepared using a sol-gel spin-coating process and the humidity sensing properties of the films are investigated. The films possess the grain size of nanometer order and nanoporous structure. The bilayered TiO₂/KT and KT/TiO₂ films exhibit a better linearity with narrower hysteresis loop in the resistance variation for relative humidity than single layered KT and TiO₂ films. The bilayered TiO₂/KT and KT/TiO₂ films show over three orders of change in the resistance during the relative humidity variation from 20 to 90%, exhibiting a good exponential relationship. The humidity sensing properties in the nanostructured-bilayered KT:TiO₂ films are discussed.     

Humidity sensing behaviors of nanocrystalline Al-doped ZnO thin films prepared by sol–gel process

Nanocrystalline Al-doped ZnO(AZO) thin films prepared by sol–gel method were used for studying the variation of resistance with humidity. The particle size of the films exhibits nanometer order with zincite structure and the thickness of the films increases linearly with the number of coatings. The AZO film coated five times and annealed at 500 °C exhibits the highest sensitivity for the humidity, which shows three order change in the resistance during the relative humidity variation from 20 to 90%. It is considered that the high humidity sensitivity is due to proton hopping between water molecules adsorbed on the film surfaces with capillary nanopores.     

聚苯乙烯蜂窝状多孔膜的制备及应用

以线性聚苯乙烯(PS)为膜材料,采用Breath Figures法制备了高度规整的蜂窝状结构多孔膜.研究了溶液浓度、环境湿度、气体吹扫速度及不同溶剂对多孔膜结构的影响.结果表明,相比于苯和二氯甲烷,氯仿作为溶剂因其挥发度适宜,PS浓度在20～80mg/mL的铸膜溶液可形成规整的蜂窝状结构多孔膜,且膜孔分布均匀、大小均一;制膜的湿度需高于环境湿度,但随着湿度的增加孔径增大;气体吹扫速度可在400～1000mL/min范围,但吹扫速度较大时孔径略有降低.该膜可作为固定诸如辣根过氧化酶等活性酶的载体,用于酶催化反应.     

LiCl/SiO2-Al2O3薄膜的纳米结构和湿敏特性

通过溶胶－凝胶工艺制得具有良好湿敏特性的ＬｉＣｌ／ＳｉＯ２－Ａｌ２Ｏ３薄膜材料,利用ＸＲＤ和ＡＦＭ对这类薄膜进行了结构表征,结果表明,具有纳米分相结构的薄膜在全湿范围内阻抗值的变化〉３个数量级,阻抗的对数值与相对湿度的关系具有较好的线性度,吸湿响应〈３０ｓ,脱湿响应〈６０ｓ。     

LiCl/SiO2-Al2O3薄膜的纳米结构和湿敏特性

通过溶胶－凝胶工艺制得具有良好湿敏特性的LiCl／SiO₂－Al₂O₃薄膜材料,利用XRD和AFM对这类薄膜进行了结构表征．结果表明,具有纳米分相结构的薄膜在全湿范围内阻抗值的变化＞3个数量级,阻抗的对数值与相对湿度的关系具有较好的线性度,吸湿响应＜30s,脱湿响应＜60s．     

Mechanical Properties of Gelatin Film

Abstract

The mechanical properties of gelatin films were investigated. We prepared gelatin films under various conditions, such as changing temperature, storage time and humidity. The stress-strain curves were obtained by measuring the tensile-strength of sample films at various humidities. These results suggest that mechanical properties of gelatin films depend on the structure and water content of the sample. It was found that the structure of gelatin films was influenced by the drying process and the thermal history of the gelatin.     

V2O5干凝胶薄膜的制备及应用

综述了V2O5干凝胶（VXG）薄膜的结构组成特性，介绍了VXG薄膜的制备方法及其在电压开关、气体传感器、湿度传感器、智能窗和锂电池等领域的应用，指出了该研究存在的问题和发展前景。     

A surface acoustic wave humidity sensor with high sensitivity based on electrospun MWCNT/Nafion nanofiber films

Humidity detection has been widely used in a variety of fields. A humidity sensor with high sensitivity is reported in this paper. A surface acoustic wave resonator (SAWR) with high resonance frequency was fabricated as a basic sensitive component. Various nanotechnologies were used to improve the sensor's performance. A multi-walled carbon nanotube/Nafion (MWCNT/Nafion) composite material was prepared as humidity-sensitive films, deposited on the surface of an SAWR by the electrospinning method. The electrospun MWCNT/Nafion nanofiber films showed a three-dimensional (3D) porous structure, which was profitable for improving the sensor's performance. The new nano-water-channel model of Nafion was also applied in the humidity sensing process. Compared to other research, the present sensor showed excellent sensitivity (above 400 kHz/% relative humidity (RH) in the range from 10% RH to 80% RH), good linearity (R(2) > 0.98) and a short response time (～3 s@63%).     

Development and mechanical characterization of solvent-cast polymeric films as potential drug delivery systems to mucosal surfaces

Solvent-cast films from three polymers, carboxymethylcellulose (CMC), sodium alginate (SA), and xanthan gum, were prepared by drying the polymeric gels in air. Three methods, (a) passive hydration, (b) vortex hydration with heating, and (c) cold hydration, were investigated to determine the most effective means of preparing gels for each of the three polymers. Different drying conditions [relative humidity – RH (6–52%) and temperature (3–45°C)] were investigated to determine the effect of drying rate on the films prepared by drying the polymeric gels. The tensile properties of the CMC films were determined by stretching dumbbell-shaped films to breaking point, using a Texture Analyser. Glycerol was used as a plasticizer, and its effects on the drying rate, physical appearance, and tensile properties of the resulting films were investigated. Vortex hydration with heating was the method of choice for preparing gels of SA and CMC, and cold hydration for xanthan gels. Drying rates increased with low glycerol content, high temperature, and low relative humidity. The residual water content of the films increased with increasing glycerol content and high relative humidity and decreased at higher temperatures. Generally, temperature affected the drying rate to a greater extent than relative humidity. Glycerol significantly affected the toughness (increased) and rigidity (decreased) of CMC films. CMC films prepared at 45°C and 6% RH produced suitable films at the fastest rate while films containing equal quantities of glycerol and CMC possessed an ideal balance between flexibility and rigidity.