高强度聚乙烯醇/氧化石墨烯复合水凝胶

采用冷冻-解冻方法制备了物理交联的聚乙烯醇/氧化石墨烯复合水凝胶。采用热失重、X射线衍射、差示扫描量热、扫描电镜、力学性能、溶胀性能及离子强度敏感性等分析对制备的复合水凝胶进行了表征,研究了氧化石墨烯(GO)含量、冷冻-解冻循环次数、聚乙烯醇(PVA)浓度对复合水凝胶性能的影响。研究结果表明,复合水凝胶呈现出三维多孔网络结构;随着GO含量的增加,水凝胶的热稳定性增强、熔融温度上升,拉伸强度和压缩强度也得到明显提高,说明GO在复合水凝胶中起到了物理交联剂的作用;复合水凝胶的平衡溶胀比随着GO含量的增加而增大,但当GO的质量分数超过0.4%时逐渐减小;增加冷冻-解冻循环次数或PVA浓度,水凝胶的拉伸强度和压缩强度增大,力学性能得到显著改善。     

医用聚乙烯醇/海藻酸钠/氧化石墨烯水凝胶的制备及性能

采用冷冻-解冻方法制备了物理交联的医用聚乙烯醇/海藻酸钠/氧化石墨烯复合水凝胶,并采用红外光谱、X射线衍射、扫描电镜、热失重等对复合水凝胶进行表征,研究了氧化石墨烯含量对复合水凝胶的结构及性能的影响。结果表明,复合水凝胶呈现三维多孔的网络结构;氧化石墨烯、海藻酸钠和聚乙烯醇之间存在强烈的氢键作用,随着氧化石墨烯含量的增加,复合水凝胶的力学性能增强,热稳定性和凝胶率也得到提高;氧化石墨烯与海藻酸钠具有协同作用促进细胞增殖,复合水凝胶具有优异的生物相容性。     

氧化石墨烯/聚丙烯酰胺/聚甲基丙烯酸复合水凝胶

以N,N-亚甲基双丙烯酰胺(BIS)为交联剂,过硫酸铵(APS)为引发剂,采用自由基引发聚合,使丙烯酰胺(AM)和甲基丙烯酸(MAA)在氧化石墨烯(GO)水溶液中进行共聚,制备了GO/PAM/PMAA复合水凝胶。研究了GO、MAA和BIS含量对复合水凝胶性能的影响。结果表明,GO/PAM/PMAA复合水凝胶具有三维网络结构,表现出pH敏感性,具有较好的药物缓释性能;热稳定性、力学性能随GO、BIS含量的增加而增强;平衡溶胀比随GO、BIS含量的增加而降低,随MAA含量的增加先增大,后减小,当n(AM)∶n(MAA)=10∶1时达到最大值。     

氧化石墨烯增强PVA-PAA复合水凝胶的制备及性能研究

水凝胶具有高含水、低摩擦、良好生物相容性等优良性能,被认为是最具潜力的软骨修复材料,但传统水凝胶因为力学强度低限制了其应用。本实验将氧化石墨烯(GO)作为增强剂,通过冷冻-解冻与退火法相结合制备了高强度的聚乙烯醇-聚丙烯酸-氧化石墨烯(PVA-PAA-GO)复合水凝胶。结果表明:PVA-PAA-GO复合水凝胶具有多孔网状结构和良好的力学强度,随着GO含量的增加,复合水凝胶的力学强度呈先上升后下降的趋势,GO含量为0.05%时,力学强度可达34 MPa,GO含量为0.05%、1%时,PVA-PAA-GO复合水凝胶的损耗因子小于0.1,与天然软骨的动态力学性能相似。     

细菌纤维素/聚乙烯醇双网络复合水凝胶的制备与性能研究

利用冷冻-解冻法制备了细菌纤维素（BC）/聚乙烯醇（PVA）双网络复合水凝胶,研究不同BC含量及循环周期对BC/PVA复合水凝胶力学性能和溶胀特性的影响,结果表明,随着BC含量的增多,复合水凝胶的含水率、平衡溶胀比、拉伸强度和压缩强度与普通的PVA水凝胶相比均有一定程度的提高;综合考虑,当BC含量为4%时,各项性能均达到最佳值;随着循环次数的增多,水凝胶内部的物理交联点增多,导致水凝胶的含水率下降,拉伸强度和压缩强度则有明显的上升趋势。SEM观察的结果与之前的分析是一致的。     

纳米羟基磷灰石/聚乙烯醇复合水凝胶的溶胀性

采用溶液共混合成法制备了纳米羟基磷灰石/聚乙烯醇(n-HA/PVA)复合水凝胶材料,研究了n-HA含量、冷冻循环次数与复合水凝胶含水率、溶胀比和溶解率之间的关系.结果表明水凝胶含水率、溶胀比和溶解率受冷冻-融化循环次数和n-HA含量的影响.随着n-HA的含量增加,含水率、溶胀比和溶解率逐渐减少.随着冷冻-融化循环次数的增加,含水率和溶解率逐渐降低而溶胀比逐渐增大.     

聚乙烯醇/淀粉复合水凝胶的辐射合成

通过辐射法制备聚乙烯醇/淀粉复合水凝胶,研究了辐照剂量和淀粉含量对聚乙烯醇/淀粉复合水凝胶的凝胶含量和溶胀率的影响.辐照剂量较小时,凝胶含量随着淀粉含量的增加明显降低,当辐照剂量大于40kGy时,凝胶含量随淀粉含量的增加下降平缓,溶胀率则随淀粉含量增加逐渐增大.红外结果分析表明淀粉与聚乙烯醇发生接枝反应.结果表明,通过...     

PEGDA/SA复合水凝胶的制备及性能研究

通过SLA 3D打印和离子交联的方法制备出聚乙二醇二丙烯酸酯(PEGDA)/海藻酸钠(SA)复合水凝胶。探究了PEGDA和SA不同含量对复合水凝胶溶胀性能、力学性能和热动态分析的影响。溶胀测试结果表明,PEGDA含量的降低或SA含量的上升的均能有效提高水凝胶的吸水速率和平衡溶胀率;压缩性能测试结果表明,SA网络的引入有助于提高凝胶的极限压缩应变和能量耗散性能,PEGDA/SA含量为50/2.5的复合水凝胶极限压缩应变达到30.4%,比相同PEGDA含量的单网络水凝胶提升了45.4%;数字散斑分析结果表明,复合水凝胶的泊松比复合水凝胶的泊松比在0.35~0.5之间;DMA结果标明,复合水凝胶在-20~100℃之间拥有相同的物质结构,SA的加入并没有影响到材料的玻璃化转变温度。     

高强度聚N,N-二甲基丙烯酰胺/氧化石墨烯复合水凝胶的制备

以N,N-二甲基丙烯酰胺(DMA)为单体,N,N-胱胺二丙烯酰胺(CBA)为交联剂,在氧化石墨烯(GO)水分散液中进行自由基原位聚合,制备了高强度PDMA/GO复合水凝胶,研究了GO和交联剂CBA的含量对复合水凝胶性能的影响。结果表明,复合水凝胶的热稳定性、拉伸强度和压缩强度随GO和CBA含量的增加而增加,其平衡溶胀比随GO含量的增加而减小。利用CBA的二硫键可以还原断裂的性质,通过热重分析测定了PDMA在GO表面的接枝效率。结果表明,GO不是简单共混在水凝胶中,而是起到了交联剂的作用,使得复合水凝胶具有优良的拉伸强度和压缩强度。     

聚乙二醇改性纳米纤维素/聚乙烯醇复合水凝胶的制备及性能

通过酸碱处理和机械研磨结合的方法制备纳米纤维素(CNFs),并利用冻融循环法分别制备了聚乙烯醇(PVA)和纳米纤维素/聚乙烯醇(CNFs/PVA)复合水凝胶,以及聚乙二醇(PEG)改性PVA和CNFs/PVA复合水凝胶。考察不同配方下复合水凝胶的微观形貌变化,并对复合水凝胶的溶胀性能、压缩强度及热稳定性能进行研究。结果表明,CNFs与PEG对PVA水凝胶的微观形貌均有改善作用,加入PEG后形成的PEG/PVA凝胶产生明显的三维网络结构。当PEG与CNFs同时加入到PVA凝胶后形成的CNFs-PEG/PVA凝胶具有均匀的互穿孔洞结构,此时复合水凝胶的孔隙率最高((67.5±4.3)%),溶胀度最好(980%),且压缩强度较PVA水凝胶也有所提升。PEG对复合凝胶的热稳定性无影响,而加入CNFs后,CNFs-PEG/PVA复合凝胶的初始热分解温度从235℃上升至300℃,显著提高了PVA凝胶的热稳定性。     

Facile preparation of low swelling,high strength,self-healing and pH-responsive hydrogels based on the triple-network structure

A polyacrylic acid(PAA)/gelatin(Gela)/polyvinyl alcohol(PVA)hydrogel was prepared by copolymerization,cooling,and freezing/thawing methods.This triplenetwork(TN)structure hydrogel displayed superior mechanical properties,low swelling ratio and self-healing properties,The superior mechanical properties are attributed to the triple helix association of Gela and PVA crystallites by reversible hydrogen bonding.The characterization results indicated that the fracture stress and the strain were 808 kPa and 370% respectively,while the compression strength could reach 4443 kPa and the compressive modulus was up to 39 MPa under the deformation of 90%.The hydrogen bonding in PVA contributed to maintain and improve the self-healing ability of hydrogels.Every type of hydrogels exhibited a higher swelling ratio under alkaline conditions,and the swelling ratios of PAA,PAA/PVA and PAA/Gela hydrogels were 27.71,12.30 and 9.09,respectively.The PAA/Gela/PVA TN hydrogel showed the lowest swelling ratio(6.57)among these hydrogels.These results indicate that the novel TN hydrogels possess good environmental adaptability and have potential applications in the biomedical engineering and sensor field.     

Cross-linked nanocomposite hydrogels based on cellulose nanocrystals and PVA: Mechanical properties and creep recovery

Cellulose nanocrystal (CNC) reinforced poly(vinyl alcohol) (PVA) hydrogels with a water content of ∼92% were successfully prepared with glutaraldehyde (GA) as a cross-linker. The effects of the CNC content on the thermal stability, swelling ratio and mechanical and viscoelastic properties of the cross-linked hydrogels were investigated. The compressive strength at 60% strain for the hydrogels with 1 wt% CNCs increased by 303%, from 17.5 kPa to 53 kPa. The creep results showed that the addition of CNCs decreased the creep elasticity due to molecular chain restriction. The almost complete strain recovery (∼97%) after fixed load removal for 15 min was observed from the hydrogels with CNCs, compared with 92% strain recovery of the neat cross-linked PVA hydrogels. The incorporation of CNCs did not affect the swelling ratio and thermal stability of the hydrogels. These results suggest the cross-linked CNC-PVA hydrogels have potential for use in biomedical and tissue engineering applications.     

细菌纤维素/聚谷氨酸复合水凝胶的辐照制备及性能

采用Co~(60)-γ射线辐照交联法制备细菌纤维素/聚谷氨酸(BC/PGA)复合水凝胶。采用红外光谱和扫描电子显微镜等对复合水凝胶的结构进行表征,研究了BC引入对复合水凝胶的凝胶分数、热失重、溶胀性能、压缩性能和流变性能的影响,并利用CCK-8法对复合水凝胶进行了细胞毒性评价。研究结果表明,辐照作用下BC纳米纤维和PGA形成双交联复合凝胶网络,BC可有效增加复合水凝胶的压缩强度、储能模量(G')和凝胶分数,降低复合水凝胶的平衡溶胀度。50kGy辐照剂量下,相对于纯PGA水凝胶,复合水凝胶压缩强度增大5倍,G'增大10倍。同时复合水凝胶无细胞毒性,可安全应用于生物医学领域。     

Poly(vinyl alcohol)/poly(acrylic acid)/TiO2/graphene oxide nanocomposite hydrogels for pH-sensitive photocatalytic degradation of organic pollutants

Poly(vinyl alcohol)/poly(acrylic acid)/TiO₂/graphene oxide nanocomposite hydrogels were prepared using radical polymerization and condensation reaction for the photocatalytic treatment of waste water. Graphene oxide was used as an additive to improve the photocatalytic activity of poly(vinyl alcohol)/poly(acrylic acid)/TiO₂ nanocomposite hydrogels. Both TiO₂ and graphene oxide were immobilized in poly(vinyl alcohol)/poly(acrylic acid) hydrogel matrix for an easier recovery after the waste water treatment. The photocatalytic activity of poly(vinyl alcohol)/poly(acrylic acid)/TiO₂/graphene oxide nanocomposite hydrogels was evaluated on the base of the degradation of pollutants by using UV spectrometer. The improved removal of pollutants was due to the two-step mechanism based on the adsorption of pollutants by nanocomposite hydrogel and the effective decomposition of pollutants by TiO₂ and graphene oxide. The highest swelling of nanocomposite hydrogel was observed at pH 10 indicating that poly(vinyl alcohol)/poly(acrylic acid)/TiO₂/graphene oxide nanocomposite hydrogels were suitable as a promising system for the treatment of basic waste water.     

Fabrication and characterization of methylene-blue-doped polyvinyl alcohol-polyacrylic acid blend for holographic recording

A methylene-blue-sensitized polymer blend of polyvinyl alcohol and polyacrylic acid is fabricated and tested for holographic recording. It was found to have good characteristics such as high sensitivity, storage stability, ease of fabrication, and environmental stability. Optimization of the ratio of polyvinyl alcohol/polyacrylic acid, the sensitizer concentration, pH, energy, diffraction efficiency measurements, etc., have been done. pH is found to have a great influence on the recovery of the dye in this matrix. The results of experimental investigations into the properties of this new material are reported.     

Study on graphene-oxide-based polyacrylamide composite hydrogels

In this paper, graphene oxide (GO) is added into poly(acrylamide) (PAM) hydrogels to modify their mechanical and thermal properties. The original PAM hydrogels, which are commonly crosslinked by N,N-methylenebisacrylamide (BIS), generally exhibit pronounced weakness and brittleness. After adding the GO into the hydrogel (BIS-gel), the GO–BIS-gels become very tough and exhibit fairly good tensile properties. The mechanical and thermal properties of GO–BIS-gels vary greatly by changing GO or BIS content. This phenomenon is probably caused by the microstructure, which related to the specific combination of GO sheets and BIS, acting as multifunctional crosslinking agents in the GO–BIS-gels. However, the BIS-gels have higher equilibrium swelling ratio than that of corresponding GO–BIS-gels. Contents of GO and BIS can be adjusted for preparing hydrogels with different applications.     

改性石墨烯/聚氯乙烯复合材料的制备及性能

采用不同含量的硅烷偶联剂γ-甲基丙烯酰氧基丙基三甲氧基硅烷（KH570）对石墨烯（GE）进行改性,将改性GE（KH-GE）与聚氯乙烯（PVC）进行熔融混炼制备KH-GE/PVC复合材料。通过FTIR、Raman、XRD、TEM和SEM表征改性前后GE结构变化,并考察了KH-GE/PVC复合材料的力学性能、导电性能及稳定性能。结果表明,GE∶KH570质量比为1∶2时,KH-GE的层间距较大,改善了GE的团聚,使GE在PVC基体中的分散得到了改善。随着KH-GE含量的增加,KH-GE/PVC复合材料的力学性能显著提高,当KH-GE质量分数为1.5wt%时,KH-GE/PVC复合材料的拉伸强度和断裂伸长率分别为23.98 MPa和226.78%,比未添加KH-GE的PVC复合材料分别提高了51.1%和65.73%;相对于纯PVC,当KH-GE质量分数为1.5wt%时,对应的50%热失重（T_50%）及90%热失重（T_90%）分别从289.81℃和486.01℃提高到298.51℃和596.53℃,提高了KH-GE/PVC复合材料的热稳定性,导电性也显著提高。     

Preparation and characterization of pH- and temperature-responsive nanocomposite double network hydrogels

A methodology is described for the preparation of pH- and temperature-responsive double network (DN) hydrogels with poly(N-isopropylacrylamide) (PNIPAM) as a tightly crosslinked 1st network, polyacrylic acid (PAA) as a loosely crosslinked 2nd network and graphene oxide (GO) as an additive. GO sheets were first prepared via an oxidation reaction and then dispersed in NIPAM aqueous solution via silanization. Free-radical polymerization of NIPAM was carried out at 20 °C in a water bath, and then subjected to UV light, leading to the formation of pH- and temperature-responsive PNIPAM/AA/GO DN hydrogels. The effects of GO sheets and AA contents on various physical properties were investigated. Results show that PNIPAM/AA/GO hydrogels undergo a large volumetric change in response to temperature. It also exhibits significantly fast swelling/deswelling compared with conventional PNIPAM hydrogel. Moreover, the PNIPAM/AA/GO hydrogels have a much better mechanical property than the conventional PNIPAM hydrogels.     

Biodegradable amylose films reinforced by graphene oxide and polyvinyl alcohol

Graphene oxide/amylose (GO/amylose) composite films with different amounts of graphene oxide (GO), glycerol and polyvinyl alcohol (PVA) were prepared by a solution casting method. The structure, morphologies, and properties of the films were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis, UV–vis spectroscopy and tensile tests. The results indicated good dispersion of the GO nanosheets in the GO/amylose composite films and consequently a significant improvement in their mechanical properties. The addition of GO increased the tensile strength of the GO/amylose films, significantly. When glycerol was used as a plasticizer, the elongation at break of the films increased. When PVA was also added to the composite films, the films were mechanically strong and flexible. The incorporation of GO also decreased the moisture absorbability and UV transmittance of the films. The stability of the GO/amylose films in acidic and alkaline solutions was also studied and the films had excellent stability in both acidic and alkaline aqueous mediums.