PVA/壳聚糖/淀粉水凝胶的制备和性能

采用反复冷冻-解冻法制备了一系列的PVA/壳聚糖/淀粉水凝胶.测试了共混膜的力学性能、脱水率和溶胀度.结果表明:壳聚糖含量为2.7%的水凝胶具有最大的断裂延伸率,拉伸强度也较高.淀粉和壳聚糖的加入,改变了复合水凝胶的脱水率和溶胀度.     

PLA/PVA/SA复合纱线的制备与表征

将聚乳酸(PLA)短纤纱与聚乙烯醇(PVA)/海藻酸钠(SA)混合水凝胶溶液复合,经冷冻、解冻、浸泡和干燥后获得水凝胶复合纱线,并进一步进行矿化处理。通过扫描电子显微镜(SEM)、能谱(EDS)、红外光谱(FTIR)、吸水率和拉伸测试对试样的形貌结构、元素组成、基团变化、亲水性和力学性能表征分析。结果表明:复合纱线中水凝胶成功披覆纱线表面并渗透入纱线内部,在纱线表面形成三维微孔结构;经矿化处理后,纱线表面沉积大量磷灰石,且磷灰石含量多于纯PLA短纤纱;与纯PLA短纤纱相比,复合纱线吸水率增加约50%,力学性能增强。该制备所得复合纱线具有良好的体外生物活性、吸水性和力学性能,可用于构建组织工程支架材料。     

PVA/PAA/Fe~(3+)超分子水凝胶的制备及其性能

为提高水凝胶的力学性能并扩展其应用,采用生物相容性良好的聚乙烯醇(PVA)、聚丙烯酸(PAA)为基质材料,以氢键和配位键为物理交联点,制备具有高力学性能的PVA/PAA/Fe~(3+)水凝胶;通过调节溶液中盐酸浓度、Fe~(3+)浓度和水凝胶浸泡时间研究其对水凝胶力学性能的影响,通过溶液的pH值探讨水凝胶的稳定性,通过循环加载-卸载实验评估水凝胶的自恢复性能。研究结果表明:红外光谱表征水凝胶网络结构氢键及配位键已形成;当溶液盐酸浓度为0.2 mol/L、Fe~(3+)浓度为0.09 mol/L、浸泡时间为20 h时,水凝胶力学强度最优,其拉伸强度为12.69 MPa,韧性为41.64 MJ/m~3;将水凝胶做一次循环加载-卸载实验之后,静置240min,其应力、应变恢复率分别达到90%、87.8%。     

高强度和自修复PAA-co-PAM/Gelatin双物理网络水凝胶的制备及性能研究

针对传统的双网络(DN)水凝胶由于缺乏有效的动态交联机制,从而很难同时实现高强度和自愈合性能的问题。文中设计制备了具有双物理网络的水凝胶聚丙烯酸-co-丙烯酰胺/明胶(PAA-co-PAM/Gelatin),在所制备的凝胶中,聚丙烯酸-co-丙烯酰胺分子链以氢键交联作为第一网络,明胶通过分子链螺旋化交联作为第二网络。分别考察了不同丙烯酸-丙烯酰胺浓度及明胶含量对DN凝胶的力学性能和自修复性能的影响。实验结果表明:当丙烯酸-丙烯酰胺总浓度为5mol·L~(-1),明胶的质量分数为30%时,制备的水凝胶性能最佳,其弹性模量可达361.8kPa,断裂强度和断裂伸长率分别为605.3kPa和835%,冲击强度和耗散能分别为4.26MJ·m~(-3)和806.5kJ·m~(-3),自修复效率大于70%。所制备的PAA-co-PAM/Gelatin凝胶兼具良好的力学强度和自愈合性能,能够在4h内快速修复表面划痕。     

电子束辐射制备pH敏感性聚乙烯醇水凝胶

应用电子束辐射交联技术制备了聚乙烯醇接枝丙烯酸(PVA-g-AAc)水凝胶。研究了pH值、AAc单体用量和辐照剂量等因素对PVA-g-AAc水凝胶溶胀率的影响。实验结果表明,在1 697cm-1处,PVA-g-AAc水凝胶的红外光谱图上出现强烈的羰基的C O特征峰,表明AAc成功接枝到PVA分子上;PVA-g-AAc水凝胶的溶胀率随PVA/AAc/H2O中AAc的质量分数和浸泡时间增加而增大;在pH=9.2时,PVA-g-AAc水凝胶具有显著的pH敏感性;辐射剂量为15kGy时,由PVA/AAc/H2O(1/1/20,质量比)混合溶液制备的PVA-g-AAc水凝胶具有较高的溶胀率;辐射剂量为5kGy时,由PVA/AAc/H2O(1/5/20,质量比)混合溶液制备的PVA-g-AAc水凝胶具有较高的溶胀率。     

PVA-Silk复合水凝胶的启动摩擦性能研究

选用高分子聚乙烯醇(PVA)和脱胶后的蚕丝(Silk)为原料,采用反复冷冻-融化法制备PVA-Silk复合水凝胶.在光学显微镜上观察PVA-Silk复合水凝胶的微现形貌,在UMT-Ⅱ型微摩擦试验机上对PVA-Silk复合水凝胶开展往复式摩擦实验,研究接触时间、滑动速率及冷冻-融化次数时复合水凝胶的启动摩擦性能的影响.结果表明,随反复冷冻-融化次数的增加,PVA-Silk复合水凝胶的交联度增大,结晶度提高,其弹性模量增大,最大法向压缩变形量减小,且其基本恢复变形所需的时间减小;PVA-Silk复合水凝胶在滑动过程中的法向位移量和最大摩擦系数随接触时间的延长而增大,随反复冷冻-融化次数的增加而减少;但最大摩擦系数与滑动速率无明显的相关联性.     

PAA/GO/Fe~(3+)水凝胶的制备及自修复性能研究

为了制备高自修复效率水凝胶,本文以丙烯酸(AA)为单体,过硫酸铵((NH4)2S2O8)为引发剂,Fe~(3+)为离子交联剂,制备了具有自修复性能的双物理交联网络PAA/GO/Fe~(3+)水凝胶。采用红外光谱仪、电子万能试验机等对凝胶进行了表征和测试,分析了GO含量、Fe~(3+)浓度对凝胶的拉伸性能、溶胀性能以及自修复性能的影响。实验结果表明:当Fe~(3+)摩尔分数x为0.5%,GO质量分数w为0.4%时,水凝胶的综合力学性能最好,拉伸强度为0.28MPa,断裂伸长率为760%;吸水倍率为70倍,自修复效率达到了62%。     

PVA/HA-Si水凝胶的制备及其促血管化机制研究

皮肤是人体最大的器官,其受到烧伤及深度伤害难以自愈,严重影响周围神经、血管等组织的功能。该文以聚乙烯醇(PVA)为基体材料,通过原位合成法引入掺硅羟基磷灰石(HA-Si),经过反复冻融制得PVA/HA-Si水凝胶。通过XRD,SEM,FTIR,CCK-8,免疫荧光以及荧光定量PCR等技术对材料进行理化表征以及生物相容性评价,探索材料浸提液对hUVECs细胞活性的影响,观测材料对hUVECs细胞形态以及血管化相关基因表达的影响。研究结果表明无机-有机复合技术制备的PVA/HA-Si材料,与纯PVA相比,细胞黏附能力显著提高,HA-Si的加入上调血管化相关因子VEGF、b-FGF和TGF-α的表达,对血管再生起到一定的促进作用。PVA/HA-Si水凝胶具有成为一种促血管化皮肤修复材料的潜能。     

PVA/PAA/BC复合水凝胶的制备与性能

利用冰冻-解冻循环法制备聚乙烯醇（PVA）/聚丙烯酸（PAA）/细菌纤维素（BC）复合水凝胶.研究BC与单体丙烯酸（AA）用量对PVA/PAA/BC复合水凝胶的力学性能和溶胀特性的影响,初步探讨PVA/PAA/BC复合水凝胶的pH敏感性.实验结果表明：随着BC添加量的增多,PVA/PAA/BC复合水凝胶的含水率和拉伸强度与PVA/PAA水凝胶相比均有一定程度的提高,SEM表明复合水凝胶的网络交联点增多;加入AA会使复合水凝胶拉伸强度减小,但溶胀性能提高很多.综合考虑,BC添加量为4%,AA添加量为8%时,各项性能均较好.     

聚乙烯醇-聚丙烯酰胺互穿网络水凝胶的制备及吸附性能

采用聚乙烯醇(PVA)、聚丙烯酰胺(PAM)为原料,戊二醛(glutaraldehyde)为交联剂,制备了一种互穿网络(IPN)水凝胶。用傅立叶红外光谱仪对其结构进行表征,研究了PVA和PAM按不同配比及交联剂的不同用量制备的IPN水凝胶的吸水性和Cu²⁺的吸附性,主要探讨了吸附时间、pH、吸附温度等对吸附Cu²⁺的影响,分析了吸附行为及其动力学特性,并对其吸附机理做出了初步探讨。结果表明：在本实验研究范围内,30wt.% PAM含量的PVA-PAM IPN水凝胶在pH=5时对Cu²⁺的吸附效果最佳;在一定温度范围内,PVA-PAM IPN水凝胶对Cu²⁺的平衡吸附量随温度升高而增大;吸附行为符合准一级和准二级动力学方程,扩散机制为颗粒内扩散和膜扩散双重作用。     

Preparation and swelling behavior of polyvinyl alcohol physiological saline gel

Polyvinyl alcohol（PVA） physiological saline gel was prepared using physiological saline solution of the polymer by freezing and thawing method. The influences of the concentration of PVA, freezing and thawing cycle times and solvent swelling media on the swelling properties of PVA saline gel were investigated. The result show that the electrolytical ions have great effect on the swelling behavior of PVA saline gel. The equilibrium swelling ratio of PVA saline gel in aqueous swelling media is larger than that in saline swelling media. Also, the equilibrium swelling ratios of PVA saline gel in aqueous and in saline media decrease with the increase of gel concentration and the increase of freezing and thawing cycle times. The decreasing speed of equilibrium swelling ratio with the increase of freezing and thawing cycle times of PVA gel in distilled water is faster than that in physiological saline. The swelling kinetic equation can sufficiently describe the swelling behavior of PVA physiological saline gel.     

Preparation and swelling behaviors of rapid responsive semi-IPN NaCMC/PNIPAm hydrogels

Semi-interpenetrating network(semi-IPN) hydrogels composed of sodium carboxylmethylcellulose(NaCMC) and poly N-isopropylacrylamide(PNIPAm) were prepared by free radical polymerization of N-isopropyl acrylamide(NIPAm) in dimethylsulfoxide(DMSO) in the presence of NaCMC. The structures of hydrogels were characterized by Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM) and differential scanning calorimetry(DSC). SEM images show that the hydrogels present porous network structures. Most water in the hydrogels were free water and freezing water. The equilibrium swelling ratio(ESR) and swelling rate(SR) were quite different at various swelling temperature. ESR of the hydrogels ranged abruptly from 15.2 g/g to 1.56 g/g and the hydrogels changed from transparent into opaque with swelling temperature changing from 33 ℃ to 34 ℃, that is to say, the hydrogels exhibited the good temperature sensitivity at about 33 ℃ similar to low critical solution temperature(LCST) of pure PNIPAm, swelling rate were very different at below and above LCST due to hydrogel swelling with different swelling mechanism. Moreover, the semi-IPN hydrogels swelled much rapidly than pure PNIPAm hydrogels did at room temperature, the equillibrium swelling ratio(ESR) and swelling rate of the hydrogels increased with increasing of NaCMC content, i e. It is suggested that NaCMC could be potential for preparation of porous and rapid swelling hydrogels     

可降解自愈合壳聚糖/瓜尔胶水凝胶的制备与性能

可降解自愈合水凝胶在生物医用领域有广泛的应用前景,然而其设计仍面临很大的挑战。用高碘酸钠氧化瓜尔胶（GG）得到醛基化瓜尔胶（AGG）。将AGG与壳聚糖（CS）混合,AGG链上的醛基与CS链上的氨基进行席夫碱（Schiff base）反应形成动态亚胺键,从而得到壳聚糖/醛基化瓜尔胶（CS/AGG）水凝胶。该水凝胶拥有较好的自愈合性和可降解性。利用核磁共振氢谱（1H-NMR）对AGG进行了结构表征,结果表明GG成功被氧化成AGG。利用动态流变性能测试对水凝胶进行模量表征,频率扫描结果表明当CS和AGG的体积比在1∶5时水凝胶储能模量最高为400 Pa;动态交替时间扫描结果表明该水凝胶能在5 min内实现快速自愈合。降解性能测试表明CS/AGG水凝胶在pH=6.8和pH=7.4的环境下7 d内降解率可达65%。所制备的CS/AGG水凝胶的自愈合性和可降解性为其在可降解医用伤口敷料和药物释放等方面的应用提供能了可能性。     

Fabrication and Characterization of One Interpenetrating Network Hydrogel Based on Sodium Alginate and Polyvinyl Alcohol

One interpenetrating network hydrogel based on sodium alginate(SA) and polyvinyl alcohol(PVA) was synthesized by combining the raw materials of PVA and SA with the double physical crosslinking methods of freezing thawing and Ca~(2+) crosslinking. The PVA-SA composite hydrogel have been characterized by scanning electron microscopy for surface morphology, infrared spectroscopy for investigating the chemical interactions between PVA and SA, X-ray diffraction for studying the PVA-SA composite structure property and thermal gravimetric for understanding the PVA-SA composite thermal stability. The swelling behavior and the degradation rate of the PVA-SA composite hydrogel were studied in simulated gastrointestinal fluid. Using bovine serum albumin(BSA) and salicylic acid as the model drugs, the release behavior of the PVASA composite hydrogel on macromolecular protein drugs and small molecule drug were evaluated. The results showed that the water absorption and degradation ability of the PVA-SA composite hydrogel was much better compared to the pure SA hydrogel or pure PVA hydrogel. The hydrogel exhibited remarkable pH sensitivity and the network was stable in the simulated intestinal fluid for more than 24 h. With the advantages such as mild preparation conditions, simple method, less reagent and none severe reaction, the PVA-SA composite hydrogel is expected to be a new prosperous facile sustained drug delivery carrier.     

Research on the friction and wear mechanism of Poly(vinyl alcohol)/hydroxylapatite composite hydrogel

Poly(vinyl alcohol)/Hydroxylapatite (PVA/HA) composite hydrogel was prepared with poly(vinyl alcohol) and hydroxylapatite as raw materials, using the method of repeated freezing and thawing. The morphologies of PVA/HA composite hydrogel were observed by means of high-accuracy 3D profiler and scanning electron microscope (SEM). The compressive elastic modulus and the stress relaxation characteristics of PVA/HA composite hydrogel were measured using the flat-head cylinder indenter. The friction and wear tests between PVA/HA composite hydrogel and bovine knee articular cartilage were performed on the micro-tribometer. The worn morphologies of PVA/HA composite hydrogel were observed with environmental scanning electron microscope (ESEM). The results showed that PVA/HA composite hydrogel has the cross-link network microstructure which is similar to that of the natural bovine knee articular cartilages. With the increase of freezing-thawing cycles and the HA content, the degree of cross-link and the crystallization of PVA/HA composite hydrogel both increase, the elastic modulus increases evidently, the rate of stress relaxation is improved and the value of balance stress decreases. The friction coefficient decreases with the increase of the freezing-thawing cycles and the HA content. The more the freezing-thawing cycles are, the earlier the friction coefficient reaches the stable balance value. The friction deformation depth between PVA/HA composite hydrogel and bovine knee articular cartilage is inversely proportional to freezing-thawing cycles and the HA content. The main wear mechanisms of PVA/HA composite hydrogel are plastic flowing and adhesive flaking. The wear severity degree decreases with the increase of freezing-thawing cycles and the HA content. Supported by Key Program of the National Natural Science Foundation of China (Grant No. 50535050), Program for New Century Excellent Talents in University (Grant No. NCET-06-0479) and Natural Science Foundation of Jiangsu Province (Grant No. BK2005403)     

Synthesis and properties of physically crosslinked poly (vinyl alcohol) hydrogels

The present study is an investigation of the properties of poly (vinyl alcohol), which would be a better contact lens material than conventional HEMA in some ways. A transparent PVA hydrogel was prepared from a PVA solution in a mixed solvent consisting of water and a water-miscible organic solvent, DMSO, by the freezing-thawing method. The water content, visible light transmittance, mechanical and swelling properties of the hydrogels were evaluated as a function of PVA concentration and number of freeze-thaw cycles. The results show that the properties of PVA hydrogels depend on the polymer concentration, the number of freeze-thaw cycles and the addition of the organic solvent.     

Preparation and Swelling Behavior of Physically Crosslinked Hydrogels Composed of Poly（vinyl alcohol） and Chitosan

The physically crosslinked poly（vinyl alcohol）/chitosan （CS） composite hydrogels were prepared by cyclic freezing/thawing techniques, and the microstructure and swelling behavior of the hydrogels in the simulated gastric （pH 1.0） and intestinal （pH 7.4） media were investigated. The experimental results of infrared spectra （IR）, scanning electron microscope （SEM） and differential scanning calorimetry （DSC） demonstrated that poly（vinyl alcohol） and chitosan had good miscibility in the composite hydrogels, and the addition of chitosan perturbed the formation of poly（vinyl alcohol） crystallites. The swelling kinetics results indicated that the composite hydrogels had good pH sensitive properties to the acidic environments, and with the increase of chitosan content in the blend, the maximum swelling degreed and the swelling rate both increased, but it led to more dissolution at pH 1.0. And the composite hydrogels also exhibited good reversible swelling behavior with pH value of the swelling medium altering between 1.0 and 7.4. In addition, the higher freezing/thawing cycle times resulted in the lower swelling rate. Therefore, the swelling behavior of the composite hydrogels could be adjusted by changing the chitosan contents and the freezing/thawing cycle times.     

原位复合纳米羟基磷灰石／聚乙烯醇水凝胶的制备及性能研究

原位合成方法制备了n—HA／PVA复合水凝胶．通过调节聚乙烯醇、纳米羟基磷灰石和水的含量，制备了不同配比的复合水凝胶．用燃烧实验、TEM、IR和XRD等对材料的组成和结构进行了表征，并测定了水凝胶的力学性质．结果表明，PVA高分子空间三维结构对羟基磷灰石晶体的原位水热生长有一定影响，复合水凝胶中n-HA与PVA有一定键合，两相分布均匀，羟基磷灰石的含量对复合水凝胶的力学强度有很大影响．     

Enhancing the formation of starch-based hybrid hydrogel by incorporating carboxyl groups into starch chains

A novel starch-based hybrid hydrogel was formed by physical and mild steps. Firstly, aqueous solution of a mixture of starch maleic half-ester (SM) and poly(vinyl alcohol) (PVA) was subjected to freezing-thawing cycles to generate a physical functional SM/PVA hydrogel. Subsequently, the SM/PVA/HA hybrid hydrogel was obtained through the alternate soaking process. The structure and morphology of the hydrogels were examined with Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). It was found that the existence of carboxylic groups on SM chains not only enabled SM/PVA hydrogel to be pH-sensitive, but also enhanced the formation of hydroxyapatite in the hydrogel via chelating calcium ions onto the matrix.     

冻融循环作用下混凝土的硫酸盐应力腐蚀特性

在质量分数为5.0%的MgSO4溶液条件下,采用快冻法和常温腐蚀方法研究了高强混凝土（High Strength Concrete,HSC）、大掺量矿物掺合料混凝土（High-Volume Mineral AdmixtureConcrete,HVMAC）和综合运用引气剂、高效减水剂、混杂纤维和膨胀剂技术的高耐久性混凝土（High Durable Concrete,HDC）的应力腐蚀行为。结果表明：无论是常温条件还是冻融循环条件,混凝土在应力腐蚀作用下的相对动弹性模量要经历强化和劣化2个发展阶段,强化和劣化阶段的时间长度与实验温度条件密切相关。冻融循环作用显著加速了混凝土的硫酸盐应力腐蚀破坏进程,HSC在冻融循环作用下应力腐蚀的强化段和劣化段的时间长度比常温条件的相应时间长度分别压缩了96%和88%以上,HVMAC的劣化段时间长度则压缩了98%,而HDC压缩了71%。在冻融循环作用下,HDC发生应力腐蚀破坏的冻融循环次数分别比HSC和HVMAC延长了1.5倍和13倍,因此,在中国寒冷地区,HDC表现出更强的抗硫酸盐应力腐蚀能力。