Preparation and antibacterial effects of PVA-PVP hydrogels containing silver nanoparticles

The poly(vinyl alcohol)/ poly(N-vinyl pyrrolidone) (PVA-PVP) hydrogels containing silver nanoparticles were prepared by repeated freezing-thawing treatment. The silver content in the solid composition was in the range of 0.1-1.0 wt %, the silver particle size was from 20 to 100 nm, and the weight ratio of PVA to PVP was 70 : 30. The influence of silver nanoparticles on the properties of PVA-PVP matrix was investigated by differential scanning calorimeter, infrared spectroscopy and UV-vis spectroscopy, using PVA-PVP films containing silver particles as a model. The morphology of freeze-dried PVA-PVP hydrogel matrix and dispersion of the silver nanoparticles in the matrix was examined by scanning electron microscopy. It was found that a three-dimensional structure was formed during the process of freezing-thawing treatment and no serious aggregation of the silver nanoparticles occurred. Water absorption properties, release of silver ions from the hydrogels and the antibacterial effects of the hydrogels against Escherichia coli and Staphylococcus aureus were examined too. It was proved that the nanosilver-containing hydrogels had an excellent antibacterial ability.

Synthesis and characterization of photo-cross-linked hydrogels based on biodegradable polyphosphoesters and poly(ethylene glycol) copolymers

Novel biodegradable hydrogels by photo-cross-linking macromers based on polyphosphoesters and poly(ethylene glycol) (PEG) are reported. Photo-cross-linkable macromers were synthesized by ring-opening polymerization of the cyclic phosphoester monomer 2-(2-oxo-1,3,2-dioxaphospholoyloxy) ethyl methacrylate (OPEMA) using PEG as the initiator and stannous octoate as the catalyst. The macrorners were characterized by H-1 NMR, Fourier transform infrared spectroscopy, and gel permeation chromatography measurements. The content of polyphosphoester in the macromer was controlled by varying the feed ratio of OPEMA to PEG. Hydrogels were fabricated by exposing aqueous solutions of macromers with 0.05% (w/w) photoinitiator to UV light irradiation, and their swelling kinetics as well as degradation behaviors were evaluated. The results demonstrated that cross-linking density and pH values strongly affected the degradation rates. The macromers was compatible to osteoblast cells, not exhibiting significant cytotoxicity up to 0.5 mg/mL. "Live/dead" cell staining assay also demonstrated that a large majority of the osteoblast cells remained viable after encapsulation into the hydrogel constructs, showing their potential as tissue engineering scaffolds.

Medicated wound dressings based on poly(vinyl alcohol)/poly(N-vinyl pyrrolidone)/chitosan hydrogels

Poly(vinyl alcohol) /poly(N-vinyl pyrrolidone) (PVP)/chitosan hydrogels were prepared by a low-temperature treatment and subsequent Co-60 -gamma-ray irradiation and then were medicated with ciprofloxacin lactate (an antibiotic) and chitosan oligomer (molecular weight = 3000 g/mol). The gel content, swelling ratio, tensile strength, and crystallinity of the hydrogels were determined. The effects of the chitosan molecular weight, the low-temperature treatment procedure, and the radiation dosage on the hydrogel properties were examined. The molecular weight of chitosan was lowered by the irradiation, but its basic polysaccharide structure was not destroyed. Repeating the low-temperature treatment and gamma-ray irradiation caused effective physical crosslinking and chemical crosslinking, respectively, and contributed to the mechanical strength of the final hydrogels. The incorporation of PVP and chitosan resulted in a significant improvement in the equilibrium swelling ratio. and elongation ratio of the prepared hydrogels. The ciprofloxacin lactate and chitosan oligomer were soaked into the hydrogels. Their in vitro release behaviors were examined, and they were found to follow diffusion-controlled kinetics.

聚环氧氯丙烷聚氨酯／聚苯乙烯IPN的玻璃化转变行为

用ＤＳＣ和动态弹粘谱（ＤＭＳ）研究了聚环氧氯丙烷聚氨酯／聚苯乙烯互穿聚合物网络［ＰＵ（ＰＥＣＨ）／ＰＳＩＰＮ］的玻璃化转变行为发现，当ＩＰＮ中聚苯乙烯（ＰＳ）含量大于２０％（质量分数）时，ＩＰＮ是不相容体系，有两个玻璃化转变ＰＳ交链度的增加，对应于ＰＵ的玻璃化转变（ＴｇⅠ）不变，对应于ＰＳ的玻璃化转变（ＴｇⅡ）向高温方向移动，转变越来越不明显，加入氨酯反应催化剂时，Ｔｇ明显内移，ＴｇⅡ内移超过２０℃，相容性增加。

聚环氧氯丙烷聚氨酯／聚（甲基丙烯酸甲酯－苯乙烯）IPN的研究

改变聚（甲基丙烯酸甲酯－苯乙烯）（Ｐ（ＭＭＡ－ｃｏ－Ｓｔ）中甲基丙烯酸甲酯的含量（Ｗ_（ＭＭＡ）），通过一步法合成出聚环氧氯丙烷聚氨酯（ＰＵ（ＰＥＣＨ）／Ｐ（ＭＭＡ－ｃｏ－Ｓｔ）ＩＰＮ．ＤＳＣ、ＴＥＭ和动态粘弹谱研究结果表明：当Ｐ（ＭＭＡ－ｃｏ－Ｓｔ）中Ｗ_（ＭＭＡ）大于０．６时，ＩＰＮ仅有一个Ｔｇ；当Ｗ_（ＭＭＡ）小于０．４时，ＩＰＮ有２个Ｔ_ｇ，ＴＥＭ上出现相区，Ｐ（ＭＭＡ－ｃｏ－Ｓｔ）溶度参数（δ）及δ的氢键作用分量（δｈ）与相态、力学性能有密切关系。

PU软段结构对PU／PMMA IPN中两组分相容性的影响

用同步法合成了４种聚氨酯／聚甲基两烯酸甲酯互穿聚合物网络（ＰＵ／ＰＭＭＡＩＰＮ），利用ＤＤＣ、ＴＥＭ和动态力学谱（ＤＭＳ）等手段综合研究了ＩＰＮ中两组分的相容性和相态结构，用基团贡献加和方法计算了各种ＰＵ和ＰＭＭＡ的溶度参数δ，结合ＰＵ软段链结构讨论了各种ＩＰＮ呈现不同相容性和相态结构的原因。

聚环氧氯丙烷聚氨酯／聚甲基丙烯酸甲酯IPN力学性能

利用改变组成比、聚氨酯ＰＵ软段（端羟基聚环氧氯丙烷）的分子量、Ｒ值（ＮＣＯ／ＯＨ）、异氰酸酯和两网络各自交联剂含量合成出５个系列的聚环氧氯丙烷聚氨酯／聚甲基丙烯酸甲酯互穿聚合物网络（ＰＵ／ＰＭＭＡＩＰＮ），利用ＩＰＮ中交联、互穿、缠结程度的不同，并结合ＤＳＣ、ＴＥＭ、动态粘弹谱讨论了ＩＰＮ力学性能。

互穿聚合物网络（IPN）形成过程的动力学研究进展

本文评述了目前在互穿聚合物网络（ＩＰＮ）形成过程的动力学研究方面所取得的成果和存在的不足。认为ＦＴ－ＩＲ是一研究复杂的ＩＰＮ体系动力学的有效手段。阐述了几种ＩＰＮ体系的形成动力学行为及其特点。

CSM/PBMA/EP三组分IPN形态及性能研究

本文用同步-分步结合的方法合成了氯磺化聚乙烯/聚甲基丙烯酸丁酯/环氧树脂(CSM/PBMA/EP)三组分IPN,对其形态及性能进行了研究。结果表明:随组成比的改变可以得到相容性不同的IPN,当CSM/PBMA/EP=40/40/20时,在动态力学谱上出现一个加宽的T_g转变峰;EP含量为9％时,得到相容性比较好的IPN。用分步染色的方法不仅可以观察三组分IPN的相区尺寸变化,也可以了解三相的相容程度。

增韧环氧树脂/蓖麻油聚氨酯IPN的性能研究

研究了端羧基丁二烯-丙烯腈共聚物增韧环氧树脂(TER)与蓖麻油聚氨酯(PU)组成的互穿聚合物网络(IPN)的应力-应变行为、密度和溶胀行为。结果表明,在TER嵌段共聚物/PU(质量比)值为某一定值时,IPN表现出补强弹性体行为,它既有较高的强度,又有很高的伸长率,断裂能也达到最大值;IPN的密度高于按共混物加合法则计算的值,溶胀度则低于计算值,说明网络间存在着互穿。

Soft matter pH sensing: from luminescent lanthanide pH switches in solution to sensing in hydrogels

The synthesis, complexation, and photophysical properties of the Eu(III)-based quinoline cyclen conjugate complex Eu1 and its permanent, noncovalent incorporation into hydrogels as sensitive, interference-free pH sensing materials for biological media are described. The Eu(III) emission in both solution and hydrogel media was switched reversibly on-off as a function of pH with a large, greater than order of magnitude enhancement in Eu(III) emission. The irreversible incorporation of Eu1 into water-permeable hydrogels was achieved using poly[methyl methacrylate-co-2-hydroxyethyl methacrylate]- based hydrogels, and the luminescent properties of the novel sensor materials, using confocal laser- scanning microscopy and steady state luminescence, were characterized and demonstrated to be retained with respect to solution behavior. Water uptake and dehydration behavior of the sensor-incorporated materials was also characterized and shown to be dependent on the material composition.