壳聚糖与聚乙烯醇磁性水凝胶的制备和性能研究

采用反复冷冻-融化技术(冻融)制备了Fe3O4/PVA/CS磁性水凝胶,并以相同方法制备了不交联、不掺磁的PVA/CS共混水凝胶和交联、不掺磁的PVA/CS交联水凝胶,研究对比了三类水凝胶的溶胀性能、再溶胀性能和力学性能随组分配比及冻融次数的变化行为,并研究了Fe3O4/PVA/CS磁性水凝胶的磁性能.结果表明:随着交联剂和Fe3O4的加入和冻融次数的增加,水凝胶的溶胀率减小,再溶胀速率减缓,但力学性能却呈现出增大趋势.Fe3O4/PVA/CS磁性水凝胶各个样品的磁滞回线皆剩磁很少,矫顽力很小,且剩磁和矫顽力的大小取决于Fe3O4掺量的大小,与冻融次数基本无关,随着Fe3O4掺量的增加剩磁和矫顽力都增大.     

冻融法制备微米级Fe3O4/聚乙烯醇磁性水凝胶及其磁力学性能研究

以微米级Fe3O4粉末和聚乙烯醇(PVA)为原料,采用反复冷冻-融化技术(冻融)制备了Fe3O4/PVA磁性水凝胶,研究了磁性水凝胶的力学性能、磁场阈值,磁性能等随Fe3O4的含量及冻融次数的变化行为,并使用扫描电子显微镜(SEM)以及X射线衍射(XRD)分别研究了Fe3O4/PVA磁性水凝胶的微观形貌和结晶性能.结果表明随冻融循环次数的增加,Fe3O4/PVA磁性水凝胶的力学性能、磁场阈值,及磁性能等均随Fe3O4的含量及冻融次数显著变化;Fe3O4在磁性水凝胶中分布均匀,PVA水凝胶经反复冷冻-融化后结晶性能有所提高.     

原位聚合法制备壳聚糖/聚丙烯酸水凝胶磁微球及其性能表征

为了避免制备过程中有机试剂对水凝胶磁微球生物安全性的影响,采用原位聚合法,在水溶液体系中制备了壳聚糖/聚丙烯酸(CS/PAAc)水凝胶磁微球.首先将壳聚糖(CS)包覆于纳米磁微球(Fe3O4)表面,随后加入丙烯酸单体,使其在壳聚糖磁微球上吸附并且原位聚合,然后经戊二醛交联得到了CS/PAAc水凝胶磁微球.用红外光谱、扫描电镜对合成的水凝胶磁微球进行了结构表征和形貌观察,并且进行了热重分析、元素分析、磁性能测试和粒度分析;研究了pH对水凝胶磁微球溶胀性能的影响.结果表明CS/PAAc水凝胶磁微球具有较好的球形结构,大小在500 nm左右;Fe3O4含量约为73%,具有良好的顺磁性质,磁饱和强度为45 emu·g-1;呈现出良好的pH敏感性,当pH=3时,CS/PAAc水凝胶磁微球的溶胀率达到最小.     

聚乙烯醇水凝胶的制备及其溶胀性能

以硼砂为交联剂,采用化学交联法制备了聚乙烯醇(PVA)水凝胶。通过测试PVA水凝胶的溶胀性能,讨论了聚乙烯醇与交联剂的最佳配比,以及盐浓度、温度、交联剂对其溶胀率的影响。结果表明,随着交联剂用量的增加,PVA水凝胶的溶胀率逐渐增大,当达到最大值时,又随着交联剂的增加而降低。随着盐浓度的增加,PVA水凝胶的溶胀率逐降低。PVA水凝胶没有温度敏感性。     

聚丙烯酸/氧化石墨烯自修复水凝胶的合成及性能

通过改进的Hummers方法成功制备了氧化石墨烯(GO)。以Fe3+为交联剂、丙烯酸(AA)为单体、GO为增强剂,采用原位聚合法制备了聚丙烯酸(PAA)/GO自修复水凝胶。考查了不同GO含量下,PAA/GO自修复水凝胶的溶胀性能,并探讨了GO含量、Fe3+含量和H2O含量对PAA/GO自修复水凝胶力学性能的影响,研究了PAA/GO自修复水凝胶的自修复性能。结果表明,Fe3+含量、GO含量和H2O单体含量分别为0.5 %（摩尔分数）、0.5 %（质量分数,下同）、80 %时,具有最佳力学性能（其拉伸强度为743.5 kPa,断裂伸长率为2940.5 %）;GO含量为0.25 %时,PAA/GO自修复水凝胶的吸水性能最大;PAA/GO自修复水凝胶具有优异的自修复性能。     

聚乙烯醇/聚丙烯酸钠/Zn0.2Fe2.8O4复合水凝胶的制备及其溶胀行为

将水溶性纳米Zn0.2Fe2.8O4(ZFO)粒子、用氢氧化钠(NaOH)中和的丙烯酸(PAAS)加入一定量的聚乙烯醇(PVA)水溶液中分散均匀,再加入引发剂过硫酸钾、交联剂N,N’-亚甲基双丙烯酰胺引发聚合,制备了PVA/PAAS/ZFO水凝胶。采用傅里叶红外光谱仪(FTIR)、透射电子显微镜(TEM)对其组成和结构进行表征,并系统研究了复合水凝胶在不同溶剂中的溶胀性能。结果表明,纳米ZFO粒子均匀分散在PVA/PAAS凝胶网络中,纳米ZFO粒子的加入使水凝胶的溶胀速率和平衡溶胀度先增加后减小,在纳米ZFO含量为1%时达到最大;在不同浓度的电解质溶液和不同pH值的溶液中进行溶胀时,水凝胶表现出良好的离子浓度和p H刺激响应性。     

聚丙烯酸钠/聚乙烯醇复合水凝胶的制备及其电响应行为

以过硫酸钾为引发剂,N, N′-二甲基双丙烯酰胺为交联剂结合冷冻-解冻交联,制备了一系列不同配比的聚丙烯酸钠(PAAS)/聚乙烯醇(PVA)互穿网络水凝胶,并用傅里叶红外光谱仪(FTIR)、场发射扫描电子显微镜(SEM)、热失重分析仪(TG)、万能试验机等对其进行表征。结果表明,PVA均匀分散于互穿网络水凝胶中,PVA的加入可以提高PAAS水凝胶的热性能;使PAAS水凝胶的溶胀速率和最大溶胀度减小,在PVA含量达到14%(质量分数,下同)时最低,随后又提高;PVA的加入可以显著提高其力学性能,断裂伸长率和拉伸强度均随PVA含量的增加而增大;PVA的加入提高了互穿网络的电响应灵敏度,且其最佳含量为21%。     

高浓度聚乙烯醇水凝胶性能研究

利用冷冻-解冻法制备了不同类型高浓度(30wt.%)聚乙烯醇(PVA)水凝胶,研究了PVA水凝胶的溶胀率、拉伸强度和流变特性。结果表明,高浓度PVA水凝胶的溶胀率受PVA的分子量和醇解度影响较大,PVA分子量越大,水凝胶的溶胀率越高;醇解度越高,溶胀率越低。随着冻融循环次数的增加,PVA水凝胶的强度增强;分子量越大,PVA水凝胶的强度反而越弱。在一定的频率范围内,PVA水凝胶的模量随着频率的增加而增加;随着冻融循环次数的增加,PVA水凝胶的储能模量增大。     

磁性半纤维素接枝聚丙烯酰胺水凝胶的制备及其性能研究

以半纤维素和丙烯酰胺为原料,利用自由基聚合法制备了多孔半纤维素接枝聚丙烯酰胺水凝胶,并且通过原位共沉淀法在凝胶上负载Fe3O4粒子,从而得到了磁性水凝胶。分别用FT-IR和SEM对水凝胶的结构和表面形态进行分析;考察了多孔半纤维素接枝聚丙烯酰胺凝胶的溶胀性能并对溶胀动力学进行了数学拟合。研究表明多孔半纤维素接枝聚丙烯酰胺水凝胶的平衡溶胀率随着交联剂量的增大而减小,随着半纤维素/丙烯酰胺比例的增大而增大,随着pH的增大而增大,水凝胶在pH=5.6的溶胀符合Schott溶胀动力学模型。振动样品磁强计(VSM)磁性能测试表明,磁性半纤维素接枝聚丙烯酰胺凝胶具有超顺磁性特征,其饱和磁化强度为10 emu/g。     

BES-Na磺酸型聚氨酯复合水凝胶的制备与性能研究

以N,N-双(2-羟乙基)-2-氨基乙磺酸钠(BES-Na)和二羟甲基丙酸(DMPA)为亲水扩链剂,原位聚合制备了一系列磺酸型水性聚氨酯(SWPU);再将丙烯酰胺(AM)引入SWPU中乳液聚合制备了一系列BES-Na磺酸型聚氨酯复合水凝胶(SWPUH)。采用傅里叶变换红外光谱(FTIR)表征了SWPUH的结构,研究了BES-Na含量对SWPUH水凝胶的溶胀性能、p H敏感性、离子强度敏感性以及力学性能的影响。结果表明,SWPUH6溶胀比最大,为33. 12,且较SWPUH1平衡溶胀比提升了50. 20%; SWPUH水凝胶还具有多重敏感性,BES-Na的加入能改善水凝胶的酸碱稳定性,且在不同离子强度溶液中,仍然具有较高的溶胀性能。另外,SWPUH水凝胶还具有优异的力学性能,其中SWPUH6水凝胶压缩强度达到最大3. 42 MPa,较SWPUH1压缩强度提升了约4. 5倍,拉伸强度最大值为0. 33 MPa,断裂伸长率最大达到了774%,相比SWPUH1分别提升了175%和59. 3%。     

3D gel printing of magnetic hydrogel scaffolds assisted by in-situ gelation in a water level-controlled crosslinker bath

Polyvinylalcohol/chitosan (PVA/CS) is an excellent dual-network hydrogel material, but some significant challenges remain in fabricating composites with specific structures. In this study, 3D gel printing (3DGP) combined with a water-level controlled crosslinker bath was proposed for the rapid in-situ prototyping of PVA/CS/Fe₃O₄ magnetic hydrogel scaffolds. Specifically, the PVA/CS/Fe₃O₄ hydrogels were extruded into the crosslinker water to achieve rapid in-situ gelation, improving the printability of hydrogel scaffolds. The effect of the PVA/CS ratio on the rheological and mechanical properties of dual-network magnetic hydrogels was evaluated. The printing parameters were systematically optimized to facilitate the coordination between the crosslinking water bath and printer. The different crosslinking water baths were investigated to improve the printability of PVA/CS/Fe₃O₄ hydrogels. The results showed that the printability of the sodium hydroxide (NaOH) crosslinker was significantly better than that of sodium tripolyphosphate (TPP). The magnetic hydrogels (PVA: CS= 1: 1) crosslinked by NaOH had better compressive strength, swelling rate, and saturation magnetization of 1.17 MPa, 92.43%, and 22.19 emu/g, respectively. The MC3T3-E1 cell culture results showed that the PVA/CS/Fe₃O₄ scaffolds promoted cell adhesion and proliferation, and the scaffolds crosslinked by NaOH had superior cytocompatibility. 3DGP combined with a water-level controlled crosslinker bath offers a promising approach to preparing magnetic hydrogel materials.     

Comparison the properties of PVA/Na+‐MMT nanocomposite hydrogels prepared by physical and physicochemical crosslinking

A novel physicochemical crosslinked nanocomposite hydrogel based on polyvinyl alcohol (PVA) and natural Na‐montmorillonite (Na⁺‐MMT) was synthesized by chemical crosslinking of nanocomposite hydrogel followed by a freezing‐thawing process. The effects of physical crosslinking, as well as physicochemical crosslinking, on the structure, morphology, and properties (thermal, mechanical, swelling, and deswelling) of nanocomposite hydrogels were investigated and compared with each other. The structure and morphology of nanocomposites were studied by Fourier transform infrared, X‐ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy techniques. The thermal and mechanical properties of nanocomposites that were affected by physical and physicochemical crosslinking were evaluated by thermogravimetric analysis, differential scanning calorimeter, dynamic mechanical analysis, hardness test, and Water vapor transmission rate (WVTR) experiments. The results showed that the physicochemical crosslinking of a PVA nanocomposite leads to a reduction in crystallinity and melting temperature, as well as an increase in the Hardness and WVTR compared to a physically crosslinked PVA nanocomposite hydrogel. The swelling and deswelling experiments were performed using a gravimetric method, and it was shown that controlled crosslinking of PVA nanocomposite hydrogel with glutaraldehyde causes the swelling ratio to increase and the cumulative amount of water loss to decrease. The swelling (sorption) and deswelling (desorption) kinetics data for physically and physicochemical crosslinking of nanocomposite hydrogels were fitted with a fickian model. It is concluded that through control crosslinking of PVA nanocomposite can lead to a hydrogel with higher swelling capacity than that is in conventional PVA nanocomposite hydrogel. POLYM. COMPOS., 37:897–906, 2016. © 2014 Society of Plastics Engineers     

辐射交联PVA/PVP/胶原复合水凝胶的制备及性能研究

采用辐射交联与冻融循环相结合的方法,将胶原引入聚乙烯醇(PVA)/聚乙烯基吡咯烷酮(PVP)水凝胶体系,制备具有较高生物活性的PVA/PVP/胶原复合水凝胶。通过含水率、溶胀性能、力学性能及微观结构研究胶原对复合水凝胶结构与性能的影响,并优选最佳体系进行体外细胞毒性实验(MTT法)。研究结果表明,复合水凝胶具有均匀分布的三维多孔结构,胶原的添加增大水凝胶网络空间结构,其初始含水率达92%,并在10 h内达到溶胀平衡,但力学性能降低。辐射交联与冻融循环相结合的方法有利于提高胶原水凝胶制备效率,胶原结构不改变,其体外细胞存活率从PVA/PVP水凝胶的77.3%提高到93.8%,细胞相容性提高。     

镁离子对PVA/GG-Mg2+复合水凝胶的结构和物理化学性质的影响

聚乙烯醇(PVA)和结冷胶(GG)构成的复合水凝胶(PVA/GG)有助于提高材料的生物相容性，在生物材料方面得到广泛的关注和应用。为进一步改善其结构和力学性质，在PVA/GG中引入Mg²⁺参与高分子链的交联，合成了PVA/GG-Mg²⁺复合水凝胶。通过分析其网络结构、力学性质、溶胀和热失水动力学，研究了Mg²⁺对分子间作用、水凝胶结构和性质的影响。结果表明在PVA/GG-Mg²⁺水凝胶中，Mg²⁺对重组网络结构、增强力学性能、强化离子与高分子的静电和氢键作用、改进水凝胶的保水性能等方面起到了很重要的作用。系统中Mg²⁺所产生的影响与PVA/GG-Ca²⁺和PVA/GG-Al³⁺复合水凝胶中Ca²⁺和Al³⁺的影响相似。研究有助于复合水凝胶在生物材料领域的应用。     

Physically crosslinked polyvinyl alcohol/chitosan/gum tragacanth hydrogels loaded with vitamin E for wound healing applications

For the healing process, in this study, an innovative polymeric hydrogel network including polyvinyl alcohol (PVA)/chitosan (CS)/gum tragacanth (GT) loaded with vitamin E (VE) was produced by the freeze–thaw approach. In order to investigate the characteristics of the prepared samples, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) analyzes were performed. Also, water vapor transmission rate (WVTR), swelling ratio, gel fraction and mechanical properties were measured. Then, to observe their cytocompatibility, MTT assay and cell adhesion studies were assessed. The results of FTIR confirmed the presence of PVA, CS, GT, and VE in hydrogel films. As well as, the SEM images showed the effect of the freezing and thawing method in creating a smooth surface with small and regular pores. It was found with adding the CS and GT to PVA improves swelling ratio, gel fraction, WVTR and elongation of hydrogel films. Further, in examining the adhesion and cytotoxicity of the samples, the non-toxic quiddity of the PVA/CS/GT hydrogel films was corroborated. In the end, the antibacterial properties revealed that the film containing GT and CS had the greatest antibacterial activity. According to the observed results, PVA/CS/GT hydrogel films loaded with VE can be good for wound healing applications.     

Porous boron nitride nanofibers/PVA hydrogels with improved mechanical property and thermal stability

Polyvinyl alcohol (PVA) hydrogel is a promising material possessing good chemical stability, high water absorption, excellent biocompatibility and biological aging resistant. However, the poor mechanical performance of PVA hydrogel limits its applications. Here we report the utilization of one-dimensional (1D) BN nanofibers (BNNFs) as nanofillers into PVA matrix to prepare a novel kind of BNNFs/PVA composite hydrogel via a cyclic freezing and thawing method. For comparison, the composite hydrogels using spherical BN nanoparticles i.e. BN nanospheres (BNNSs) as fillers were also prepared. The mechanical properties, thermal stabilities and swelling behaviors of the composite hydrogels were investigated in detail. Our study indicates that the mechanical properties of the hydrogels can be improved by adding of BNNFs. After loading of BNNFs into PVA with content of 0.5?wt%, the compressive strength of the composite hydrogel increases by 252% compared with that of pure PVA hydrogel. The tensile performance of BNNFs/PVA composite hydrogels has also been improved. Impressive 87.8% increases in tensile strengths can be obtained with 1?wt% BNNFs added. In addition, with the increase of BNNFs content, the thermal stability and the swelling ratio of hydrogels are increased gradually. The swelling ratio of hydrogel increases by 56.3% with only 1?wt% BNNFs added. In comparison, the improvement effects of the BNNS fillers on the mechanical strengths and swelling ratios are much weaker. The enhanced effects of BNNFs can be ascribed to the strong hydrogen bond interaction between BNNFs and PVA. The high aspect ratios of the nanofibers should also be took into account.     

磺化β-环糊精/PVA凝胶电刺激响应行为的研究

首先将β-环糊精(β-CD)和聚乙烯醇(PVA)用戊二醛交联制成凝胶;然后以浓硫酸作为改性剂,将磺酸根引入凝胶中,制备出一种阴离子型磺化β-CD/PVA凝胶,并对该凝胶的平衡溶胀率、粘接性能和电刺激响应行为等进行了研究。结果表明:该凝胶在Na2SO4水溶液中的平衡溶胀率随离子强度增加而减小;其剪切强度随PVA含量增加呈先升后降态势,并且在w(PVA)=5%时相对最大(3.8 MPa)。在非接触性直流电场作用下,该凝胶在Na2SO4水溶液中弯向电场负极,其弯曲偏转速率和应变随外加电压增加而增大,并且在离子强度为0.15 mol/L时相对最大;在循环电场作用下,该凝胶的电刺激响应行为具有良好的重现性和可逆性。     

室温交联PVA水凝胶的制备与性能研究

以环氧氯丙烷为交联剂,采用室温化学交联法制备了聚乙烯醇(PVA)水凝胶,研究了交联温度和交联时间对PVA溶胀性能和力学性能的影响,借助差示扫描量热法(DSC)和扫描电子显微镜(SEM)对PVA水凝胶进行分析表征。结果表明,当交联时间为3d且交联温度为50℃时PVA水凝胶的综合性能最佳。PVA的玻璃化转变温度为-54.50℃,PVA水凝胶中包含有自由水、束缚水和非冷冻水。     

蒽改性聚乙烯醇水凝胶的制备与表征

首先以蒽甲醛和聚乙烯醇(PVA)为原料、二甲基亚砜(DMSO)为溶剂、对甲苯磺酸(TsOH)为催化剂,反应得到蒽接枝改性聚乙烯醇(AnPVA)。然后利用混合溶剂凝胶法制备AnPVA水凝胶。通过差示扫描量热法(DSC)、拉伸等测试,研究水凝胶的力学等性能。结果表明,相比于纯PVA水凝胶,AnPVA水凝胶的力学性能得到了显著提高,在水凝胶中引入疏水基团是一种十分有效提高水凝胶力学性能的手段。AnPVA水凝胶浸泡于水中加热后无明显溶胀,有着优异的耐热和耐水性能,并且该水凝胶是物理交联网络,有着良好的循环重塑性能。