Preparation and Characterization of Nano-hydroxyapatite/polyvinyl Alcohol Gel Composites

Nano-hydroxyapatite reinforced poly（vinyl alcohol） gel（nano-HA/PVA gel） composites has been proposed as a promising biomaterial,especially used as an articular cartilage repair biomaterial.In this paper,nano-HA/PVA gel composite was prepared by in situ synthesis method and incorporation with freeze-thaw cycle process.The microstructure and morphology were investigated by X-ray diffraction,TEM,SEM and FTIR.The results showed that the size of HA particles synthesized in PVA solution was on the nanometer scale.Both the size and crystallinity of HA particles synthesized in PVA solution decreased compared with that of HA synthesized in distilled water.The nano-HA particles were distributed in PVA matrix uniformly due to the effect of PVA solution as a dispersant while low content of HA particles in the composites.On the contrary,with high content of nano-HA particles in the composites,the particles tended to aggregate.The result of FT-IR analysis indicated that the chemical bond between nano-HA particles and PVA matrix existed.The conformation and degree of tacticity of PVA molecule changed because of the addition of HA particles.Furthermore,the interfacial strength of the composites was improved due to the interaction between nano-HA particle and PVA matrix and this was beneficial to improving the mechanical properties of the composites.

PVA/MMT/TiO_2三元复合薄膜制备与研究

通过插层法和溶胶-凝胶法制备了PVA/MMT/TiO2三元复合薄膜。结果表明,MMT、TiO2均匀分散于基体中,由于无机粒子的协同增强作用,PVA/MMT/TiO2三元复合薄膜的热分解温度比纯PVA薄膜提高了59℃。MMT的质量一定时,复合薄膜的拉伸强度、直角撕裂强度和弹性模量随TiO2质量分数的增加而增加,并在TiO2质量分数为1.0%时分别达到最大值,但断裂伸长率则一直下降。MMT质量分数为3.0%、TiO2质量分数为1.0%、pH为7、搅拌3h和反应温度90℃条件下,制得的复合薄膜的性能最佳。

Dex/PVA复合凝胶的制备及其对辅酶A的控制释放

以葡聚糖-20(Dex)为原料,运用冷冻干燥法,在水相体系中制得粒径为100～200 nm的微凝胶.采用微波-冻融、冷冻干燥法在聚乙烯醇(PVA)凝胶中嵌入Dex微凝胶,生成Dex/PVA的复合凝胶,并用红外光谱、X-粉末衍射和透射电镜表征了Dex微凝胶的结构,用扫描电镜表征了Dex/PVA复合凝胶的微观形貌.溶胀试验和力学性能测试表明,Dex/PVA复合凝胶具有Dex微凝胶的环境响应性和PVA凝胶的力学性能.在不同温度、不同pH值条件下,用复合凝胶在辅酶A质量分数为0.80%的缓冲溶液中制得样品进行药物控制释放试验.结果显示,复合凝胶对辅酶A的控制释放具有温度和pH值敏感性,在温度10℃,pH=4.5的磷酸缓冲溶液中,含有30%Dex微凝胶的PVA复合凝胶能较好地控制辅酶A的释放,释药动力学方程为Rc=100t0.27/(1.47+6.56t-0.23),R2=0.998 9.

溶解纤维素-PVA复合凝胶的制备及其性能研究

将微晶纤维素溶解于N-甲基吗啉-N-氧化物(NMMO)溶剂体系,并与聚乙烯醇(PVA)NMMO溶液混合,采用溶胶-凝胶工艺制备纤维素-PVA复合凝胶,探究不同凝固浴对复合凝胶性能的影响,并利用X射线衍射(XRD)、热重分析(TGA)、扫描电子显微镜(SEM)等表征手段考察了复合凝胶的晶体结构、热稳定性、微观结构等性能,讨论基于NMMO溶剂体系纤维素与PVA复合的成胶机理。结果表明,与分别以水及无水乙醇为凝固浴制得的复合凝胶相比,以20%NMMO/1%硼砂为凝固浴制得的复合凝胶无裂纹,且具有良好的韧性,机械性能最佳;经NMMO溶解后制得的纤维素凝胶由纤维素Ι型转变为纤维素Ⅱ型,而经1%硼砂交联后制得的纤维素-PVA复合凝胶在2θ=13.18°和19.46°处出现新的结晶峰,其为PVA的衍射峰,说明纤维素与PVA交联复合;热重分析显示,与纤维素凝胶相比,纤维素-PVA复合凝胶的热稳定性显著提高,热降解初始温度从270℃升高至280℃左右;利用SEM可观察到经硼砂交联后的纤维素-PVA复合凝胶的孔隙约500nm,相对于纤维素凝胶,其孔隙结构更均匀紧凑。