聚乙二醇双丙烯酸酯交联剂的合成工艺

研究了高吸水性树脂交联剂聚乙二醇双丙烯酸酯的合成工艺。结果表明:在丙烯酸1 mol、n(聚乙二醇)∶n(丙烯酸)=1∶3、环己烷15 mL、甲苯5 mL、催化剂对甲苯磺酸0.018 mol、反应温度90℃和反应时间8 h等试验条件下,产物收率96.7%(x);用优化条件下合成的交联剂制备聚丙烯酸钠高吸水性树脂,其吸水倍率690.2、吸盐水107.5、吸人工尿51.1、吸水速率10.1 s。     

聚乙二醇定形相变材料的热稳定性

利用热重分析仪对不同分子量、不同支撑材料、不同配方的聚乙二醇(PEG)定形相变材料的热稳定性进行了分析。结果表明,机械加工方法有可能会对PEG分子链有破坏作用,PEG定形相变材料具有良好的热稳定性。随着PEG分子量的增加,PEG定形相变材料的热分解温度越来越高,热稳定性更好。活性炭颗粒(ACG)和膨胀石墨(EG)都会使PEG相变材料的热分解温度降低,热稳定性有所降低。随着PEG定形相变材料中支撑材料含量的增加,定形相变材料的热稳定性降低。     

PET—PEG嵌段共聚物的热性能和流变性

酯交换法合成了一系列不同ＰＥＧ含量的ＰＥＴ－ＰＥＧ嵌段共聚物，并以差示扫描量热法研究了这些嵌段共聚物及纯ＰＥＴ的热性能。用毛细管流变仪研究了不同温度和不同长径比条件下它们的流为性能。     

星型聚乙二醇对甲苯磺酸酯的合成

分别用三羟甲基丙烷和季戊四醇的相应溴化物与多甘醇单钠盐醚化后,经对甲苯磺酰化反应,得到一类星型聚乙二醇对甲苯磺酸酯。产物经元素分析、核磁共振谱、质谱证实其分子结构。     

槲皮素-聚乙二醇固体分散体对亚硝化反应的抑制作用

以槐米为原料制备槲皮素。为改善槲皮素的水溶性,以聚乙二醇为载体,采用熔融法将其制成槲皮素-聚乙二醇固体分散体,使其在水中的溶解度由11．8mg／L提高到80．2mg／L。在模拟人体胃液的条件下,考察该分散体对亚硝化反应的抑制作用。结果表明,槲皮素-聚乙二醇固体分散体对亚硝化反应具有较强的抑制作用,其对亚硝胺合成的最大阻断率达91.3％,对亚硝酸钠的最大清除率为86．1％。     

Temperature- and pH-sensitive core–shell nanogels as efficient carriers of doxorubicin with potential application in lung cancer treatment

Temperature- and pH-sensitive core–shell nanogels were prepared by one-pot soapless emulsion polymerization of N-isopropylacrylamide and 2-methacryloyloxy benzoic acid with the aid of a crosslinker (core) using poly(ethylene glycol) methyl ether methacrylate as stabilizer (shell). The size of nanogels depended on the crosslinker used, being considerable smaller (around 100?nm) with the use of the acid-labile crosslinker 9-divinyl-2,4,8,10-tetraoxaspiro[5.5]-undecane (DVA). Doxorubicine (DOX) was loaded in nanogels with good efficiency. The empty nanogels were biocompatible for a lung cancer cell line (NCI-H1437), while the DOX-loaded, DVA-crosslinked nanogels resulted with efficient cytotoxicity for that cell line.     

希土镝改性铁氧体磁流体的制备与表征

采用化学共沉淀法制备了水基镝复合铁氧体磁流体,研究了操作温度、镝的用量、表面活性剂的加入方式、pH值对磁性能的影响,通过多次实验总结出适宜的条件：25％NH3·H2O作为沉淀剂和pH值的调节剂,在n（Fe^3＋）：[n（Fe^2＋）＋n（Dy^3＋）]=1：1下,反应体系温度控制在35℃左右,调pH值至％10,镝的用量为24ml[n（Fe）：n（Dy^3＋）=14：1]。对产品的形貌、粒度、黏度、磁化强度、稳定性等进行了相应的表征,结果表明制得的水基磁流体磁性显著提高。     

A new chain extension reaction on poly(lactic–glycolic acid) (PLGA) thermal oligomers leading to high molecular weight PLGA-based polymeric products

A novel and effective chain-extension procedure for obtaining high-molecular-weight PLGA-based bioerodible polymers is described. This procedure consists in a polycondensation reaction between PLGA thermal oligomers of average molecular weight 1000–3000 and bischlorofomates of either simple diols or α,ω-bis-hydroxylated oligomers, such as polyethyleneglycols or bis-hydroxy terminated poly-ε-caprolactones. In the latter case, multiblock copolymers are obtained. By varying the nature and the length of the starting diol, as well as the lactic/glycolic acid molar ratio in the starting PLGA oligomer, products with widely different physicochemical properties can be synthesized. In particular, dissolution times in aqueous media can be tuned within an ample range, from a few days to several months. This provides exceptional opportunities for designing products whose properties are tailored in view of specific applications in the biomedical field. © 1998 SCI.     

Silicate-based polymer-nanocomposite membranes for polymer electrolyte membrane fuel cells

Proton-exchange membrane fuel cells have emerged as a promising emission free technology to fulfill the existing power requirements of the 21st century. Nafion^® is the most widely accepted and commercialized membrane to date and possesses excellent electrochemical properties below 80 °C, under highly humidified conditions. However, a decrease in the proton conductivity of Nafion^® above 80 °C and lower humidity along with high membrane cost has prompted the development of new membranes and techniques. Addition of inorganic fillers, especially silicate-based nanomaterials, to the polymer membrane was utilized to partially overcome the aforementioned limitations. This is because of the lower cost, easy availability, high hydrophilicity and higher thermal stability of the inorganic silicates. Addition of silicates to the polymer membrane has also improved the mechanical, thermal and barrier properties, along with water uptake of the composite membranes, resulting in superior performance at higher temperature compared to that of the virgin membrane. However, the degrees of dispersion and interaction between the organic polymer and inorganic silicates play vital roles in improving the key properties of the membranes. Hence, different techniques and solvent media were used to improve the degrees of nanofiller dispersion and the physico-chemical properties of the membranes. This review focuses mainly on the techniques of silicate-based nanocomposite fabrication and the resulting impact on the membrane properties.     

聚乙二醇掺杂聚苯胺复合材料气敏性能的研究

以聚乙二醇(PEG)为掺杂剂,过硫酸铵(APS)为引发剂,用一步乳液聚合法合成PAN/PEG复合物.通过控制变量法,考察了不同制备因素对PAN/PEG乳液稳定性和复合材料气敏性能的影响,优化得到合成过程中最佳实验参数:n(DBSA)/n(An)=1.0,n(APS)/n(An)=1.0,n(PEG)/n(An)=2,聚...