Volumetric Change and Surface Properties of Temperature-Sensitive Polyvinylalcohol (PVA) Hydrogel

Polyvinylalcohol (PVA) polymer gel is a temperature sensitive polymeric gel, with a critical transition temperature (with H₂O) of 310 K. At higher than 310 K, this temperature sensitive polymer gel shrinks because of discharging water, whereas at lower temperatures, the gel swelled because of absorbing water. The reversibility of the gel's volume change was confirmed by temperature swing. The adsorption behavior of an organic compound onto the PVA polymer gel in water was tested at various temperatures. The amount of adsorbed organic compound increased remarkably at temperatures higher than about 310 K. Then, it was confirmed that the organic compound in PVA polymer gel could be reversibly adsorbed and desorbed by a temperature change between 293 and 323 K. The mechanism of adsorption of the organic compound onto the PVA polymer gel could be explained by hydration and dehydration of polymer gel.     

高聚合度聚乙烯醇的制备研究

制备高聚合度聚乙烯醇的方法有乳液聚合法,辐射聚合法,超低温复合乳液聚合法等。本文采用低温乳液聚合法制备聚合度在2000以上的聚乙烯醇,此方法具有容易实现工业化,聚合率高的特点。     

Hydrogels Formed by Cross-Linked Polyvinylalcohol as Colon-Specific Drug Delivery Systems

Polyvinylalcohol (PVA) of different molecular weights was cross-linked with succinyl, adipoyl, or sebacoyl chloride to obtain hydrogel-forming polymers and to determine their suitability as colon-specific drug delivery systems. Diclofenac sodium, propranolol hydrochloride, and vitamin B6 hydrochloride were used as hydrophilic model drugs with colon-specific release that should yield high concentrations in the large intestine, minimizing release in the upper part of the gastrointestinal tract. Spray-dried mixtures of the drugs and the polymer (at a 1 : 2 w/w ratio) were prepared, and the release of the drugs from the mixtures was evaluated in vitro at pH 2.0, 5.5, and 7.4. The results indicated the ability of the cross-linked polymers to slow the release of the drugs analyzed with respect to the pure drug dissolution at each pH. The lengthening of the cross-linker acyl chain was noted to decrease drug release further.     

PVA对碳酸钙、淤泥/不饱和聚酯树脂体系增强的探讨

采用聚乙烯醇(PVA)对碳酸钙、淤泥进行改性并将其作为不饱和聚酯树脂填料。研究了PVA掺量对碳酸钙/不饱和聚酯树脂和淤泥/不饱和聚酯树脂体系力学性能的影响。采用IR、DSC和SEM探讨了PVA对这2类体系的改性机理。实验结果表明:加入5%PVA后,碳酸钙/树脂体系,淤泥/树脂体系弯曲强度分别提高了55.3%和58.4%。PVA对2种体系的改性增强效应均源于PVA与填料和树脂之间氢键的桥梁作用,氢键改善了无机填料与树脂的相容性,这与以往改性剂与碳酸钙反应生成酯酸钙固化物的机理是不同的。     

Amino‐polyvinyl Alcohol Coated Superparamagnetic Iron Oxide Nanoparticles are Suitable for Monitoring of Human Mesenchymal Stromal Cells In Vivo

Mesenchymal stromal cells (MSCs) are promising candidates in regenerative cell‐therapies. However, optimizing their number and route of delivery remains a critical issue, which can be addressed by monitoring the MSCs’ bio‐distribution in vivo using super‐paramagnetic iron‐oxide nanoparticles (SPIONs). In this study, amino‐polyvinyl alcohol coated (A‐PVA) SPIONs are introduced for cell‐labeling and visualization by magnetic resonance imaging (MRI) of human MSCs. Size and surface charge of A‐PVA‐SPIONs differ depending on their solvent. Under MSC‐labeling conditions, A‐PVA‐SPIONs have a hydrodynamic diameter of 42 ± 2 nm and a negative Zeta potential of 25 ± 5 mV, which enable efficient internalization by MSCs without the need to use transfection agents. Transmission X‐ray microscopy localizes A‐PVA‐SPIONs in intracellular vesicles and as cytosolic single particles. After identifying non‐interfering cell‐assays and determining the delivered and cellular dose, in addition to the administered dose, A‐PVA‐SPIONs are found to be non‐toxic to MSCs and non‐destructive towards their multi‐lineage differentiation potential. Surprisingly, MSC migration is increased. In MRI, A‐PVA‐SPION‐labeled MSCs are successfully visualized in vitro and in vivo. In conclusion, A‐PVA‐SPIONs have no unfavorable influences on MSCs, although it becomes evident how sensitive their functional behavior is towards SPION‐labeling. And A‐PVA‐SPIONs allow MSC‐monitoring in vivo.     

Physico-Chemical Characterisation of the Influence of Moisture on the Fibre/Matrix Interaction in Epoxy/Anhydride Composites

The effect of moisture on the fibre/matrix interaction in epoxy/anhydride composites is investigated and explained through the characterisation of the matrix cure in the interphase. The fibre/matrix interaction is inferred from ILSS measurements on the composite, which are compared with a recently-introduced DSC interaction parameter. The matrix cure in the bulk as well as in the interphase is characterised through FT-IR microspectroscopy. Complementary information is gained by measuring the overall T_g value. Moisture is shown to lower the fibre/matrix interaction if the prepreg (= composite precursor) is stored at room temperature or lower prior to final cure. This is due to the reduced crosslink density of the matrix. For PE prepreg stored in ordinary atmospheric conditions, moisture from the surroundings lowers the fibre/matrix interaction sharply. If the prepreg is stored in a dry environment, nearly no effect of the storage is detected on the fibre matrix interaction in PE (polyethylene) fibre composites, while for PVAL (polyvinylalcohol) fibre composites a strong decrease is still found, caused by water adsorbed at the more hydrophilic fibre surface.     

可完全生物降解塑料

本文论述了降解塑料的定义,淀粉基降解塑料的研究现状,以及可生物降解性及其评价方法     

高强高模聚乙烯醇纤维研究进展

本文主要介绍近年来高强高模聚乙烯醇纤维研究在聚合度选择、纺丝方式、拉伸方式、溶剂选择、凝固条件以及萃取等方面的新进展及其在产业上的应用。     

聚乙烯醇基中空活性炭纤维的制备——碳化过程的研究

讨论了用聚乙烯醇纤维制备活性炭纤维的碳化过程中，纤维成分、结晶形态及物理织构的变化，并指出了中空结构的形成过程和影响因素。获得较高得率的均匀活性炭纤维，应采用７℃／ｍ ｉｎ 较慢的升温速率。     

聚乙烯醇/蒙脱石纳米复合材料的多尺度模拟

采用分子动力学(MD)和耗散粒子动力学(DPD)方法对聚乙烯醇(PVA)/蒙脱石(MMT)纳米复合材料进行多尺度模拟,通过一定的映射规则由MD模拟所得含不同聚合度(DP)的PVA复杂体系界面结合能数据计算DPD模拟所需相互排斥作用参数。并对相同组成下的水溶剂化PVA/MMT纳米复合材料分别进行NPT系综MD模拟和介观DPD模拟,发现不同尺度模拟方法所得最终平衡构象分布规律一致。