全物理交联三重互穿网络水凝胶的制备与性能

为提升水凝胶的综合力学力学性能,设计并研究了一种全物理交联三重互穿网络水凝胶.以自由基乳液聚合法,获得疏水缔合交联的聚丙烯酰胺网络,水凝胶一步成型,依次通过冷冻-融化循环、浸没FeCl3溶液分别形成微晶交联的聚乙烯醇网络及离子交联的海藻酸钠网络.获得P(AM-SMA)/PVA/SA三重互穿网络(HMITN)水凝胶.通过...     

双交联聚乙烯醇/海藻酸钠水凝胶的制备与表征

以聚乙烯醇(PVA)与海藻酸钠(SA)为原料,利用CaCl_2/硼酸溶液进行化学交联,再通过循环冷冻解冻物理交联,制备出PVA/SA水凝胶。分析讨论了水凝胶的交联机理、结构、力学性能、含水率、孔隙率及细胞相容性。红外光谱分析表明,经CaCl_2/硼酸溶液交联后,Ca~(2+)与SA中的-COO~-形成络合,硼酸溶液中B(OH)_4~-与PVA交联形成交联结构,循环冷冻解冻促使了复合水凝胶中分子间和分子内氢键的形成。扫描电镜测试表明,PVA/SA水凝胶内部具有丰富的多孔结构,孔径约5～30μm。水凝胶的性能可通过交联剂浓度等进行调控,其中m(PVA)/m(SA)为8∶2,交联剂质量分数为5%时,水凝胶压缩模量和压缩强度分别达到(121.84±3.03) kPa和(636.18±68.71) kPa;含水率和孔隙率分别为83.73%和79.98%。细胞培养结果表明,双交联PVA/SA水凝胶细胞相容性良好。     

高强度超拉伸全物理交联双网络水凝胶的制备与性能

以锂藻土(Laponite)与聚丙烯酰胺(PAM)间的氢键交联作用网络形成第1网络、以三价铁离子(Fe~(3+))与海藻酸钠(Alginate)间的离子交联作用形成第2网络,制备了锂藻土-聚丙烯酰胺/Fe~(3+)-海藻酸钠(Laponite-PAM/Fe~(3+)-Alginate)全物理交联双网络水凝胶。通过扫描电镜表征了Laponite-PAM/Fe~(3+)-Alginate双网络水凝胶的微观结构,探究了Fe~(3+)浓度和锂藻土含量对Laponite-PAM/Fe~(3+)-Alginate双网络水凝胶力学性能的影响,并通过拉伸-回复测试表征了水凝胶的回复性能和抗疲劳性能。结果表明,Laponite-PAM/Fe~(3+)-Alginate全物理交联双网络水凝胶内部具有致密的三维网络结构,其断裂强度可达2.4 MPa,断裂伸长率可达2600%,韧性可达44.8 MJ/m~3,具有优异的力学性能、良好的回复性能及抗疲劳性能。     

聚乙烯醇/聚丙烯酸水凝胶的电刺激响应性研究

通过冰冻－解冻循环方法制备了机理交联水凝胶聚乙烯醇（PVA）／聚丙烯酸（PAA），研究了该水凝胶在直流电场作用下的弯曲响应性质，考察不同浓度和组成的凝胶在0．01mol/L Na2Co3电解质水溶液中，。作用电场的电场强度对凝胶弯曲速率的影响，以及电解质溶液的浓度对凝胶弯曲速率的影响，初步探索了凝胶在电场作用下的弯曲机理。     

离子双交联海藻酸钠/聚(丙烯酰胺-co-丙烯酸)高强度水凝胶的研究

利用海藻酸盐分子和共聚物链上丰富的羧基与多价金属离子的高配位能力,采用"一步法"离子双交联制备了高强度、高韧性的海藻酸钠/聚(丙烯酰胺-co-丙烯酸)-Fe~(3+)(S/P-Fe~(3+))双网络水凝胶。对浸泡多种金属离子(Na~+、Ca~(2+)、Cu~(2+)、Al~(3+)、Fe~(3+))溶液得到的金属离子双交联水凝胶的力学性能展开研究,结果表明,随着金属离子价态的升高,水凝胶的力学强度逐渐增大,其中铁离子的增强效果最好。通过优化SA含量、AAc与AAm的比例以及Fe~(3+)浓度,获得最佳配比的S/P-Fe~(3+)(SA 2%(质量分数,下同),AAc 5%(摩尔分数,下同)和Fe~(3+)0.06 mol/L)高强度水凝胶,其力学性能优越(拉伸强度3.24 MPa,断裂伸长率1 228%),同时该离子双交联高强度水凝胶还具有高的含水量(76%)。此外,S/P-Fe~(3+)水凝胶的交联强度受环境影响,通过p H值变化可调节其力学性能,使其具备形状记忆性。     

聚苯乙烯-马来酸钠/纤维素复合纤维水凝胶的制备及其药物释放研究

研究了用静电纺丝制备聚苯乙烯-马来酸酐共聚物(SMA)/醋酸纤维素(CA)复合超细纤维。通过一缩二乙二醇(DEG)交联,并在0.05mol/L NaOH/乙醇溶液中水解制得SMA-Na-DEG/纤维素超细纤维水凝胶。对其结构和拉伸性能进行了分析和测试,结果表明:该水凝胶pH响应良好,pH=9.1时,溶胀比达到最大值27.6g/g;加入纤维素后,水凝胶的力学性能明显提高。此外,还以水杨酸为药物,评估了SMA-Na-DEG/纤维素水凝胶的药物释放行为,并探讨了其释放机理。     

阿魏酸交联处理对明胶性质的影响

采用恒重法测定了交联明胶在25℃的水吸附等温曲线,分别用质构仪和乌氏黏度计测定了不同浓度阿魏酸交联明胶溶液的凝胶强度和黏度,评价了阿魏酸交联处理对明胶的水吸附性、胶凝性和黏性的影响。结果表明:在水分活度相同的条件下交联明胶的平衡含水量在水分活度较低时略低于明胶,而在水分活度较高时则略高于明胶;可以用GAB模型很好地拟合水吸附等温数据;交联明胶溶液形成凝胶的临界质量浓度为0.7%g/m L,与明胶接近;在临界浓度以上交联明胶的凝胶强度随着溶液浓度的增加而提高,但是明显地比相同浓度下明胶的强度低;交联明胶的特性黏数(354.38 m L/g)比明胶的(85.80 m L/g)高。     

Cu/Zn/Ce/ZSM-5分子筛的碱改性及催化性能研究

采用NaOH溶液和金属离子(Cu~(2+)、Zn~(2+)、Ce~(4+))改性ZSM-5分子筛。通过SEM、XRD等表征手段,探讨NaOH溶液浓度、Cu/Zn/Ce物质的量比以及不同制备方法对ZSM-5分子筛形貌及性能的影响。以光催化辅助降解酸性大红GR模拟废水,考察改性后的ZSM-5分子筛的催化活性。结果表明,当NaOH溶液的浓度为0.2mol/L、Cu负载量为8%、Cu/Zn/Ce物质的量比为8∶4∶1、制备方法为溶胶-凝胶法时,分子筛的催化性能最佳,离子溶出量较小。     

前驱溶液的碱浓度对BiVO4粉体的微波水热法制备及光催化性能的影响

以Bi(NO3)3·5H2O和NH4VO3为原料,采用微波水热法在200℃不同前驱液碱浓度下制备了BiVO4粉体。利用XRD、FE-SEM、BET、UV-Vis等手段研究了前驱液碱浓度对BiVO4晶型、结构及形貌的影响,并对不同前驱液碱浓度下合成粉体的光催化性能进行了研究。溶于纯水获得的粉体是单斜相和四方相1～3μm八面体结构的BiVO4混晶。溶于HNO3和NaOH溶液时制得粉体为纯单斜相3μm大小球状BiVO4,NaOH增加到4mol/L时为2μm大小鱼排骨状BiVO4的混晶。光催化结果表明,紫外光下光催化活性顺序为:BiVO4(纯水)>BiVO4(4mol/L NaOH)>BiVO4(2mol/L NaOH),可见光下光催化活性顺序为:BiVO4(4mol/L NaOH)>BiVO4(纯水)>BiVO4(2mol/L NaOH)。     

聚天冬氨酸/木质纤维素水凝胶制备及溶胀性能研究

采用水溶液聚合法合成聚天冬氨酸/木质纤维素(PASP/LNC)水凝胶;运用SEM、TGA和FT-IR对水凝胶的结构进行表征;考察预处理时间、预处理温度、高锰酸钾(KMnO_4)浓度、戊二醛用量、聚天冬氨酸(PASP)用量、反应时间以及反应温度对PASP/LNC水凝胶溶胀性能的影响。实验结果表明:预处理时间15min,预处理温度50℃,KMnO_4浓度0.06mol/L,戊二醛用量lg,PASP用量11g,反应时间3.5h,反应温度70℃时,水凝胶溶胀性能最佳,最大溶胀比为10.92。     

交联剂对PVP/PCL共聚凝胶性能的影响

研究了N,N-亚甲基双丙烯酰胺(NMBA)、戊二醛(GDA)两种交联剂对聚乙烯吡咯烷酮(PVP)/聚己内酯(PCL)共聚水凝胶性能的影响。交联剂含量低于NVP的0.7%时,GDA交联凝胶平衡溶胀率ESR较高,高于0.7%时,NMBA交联凝胶的ESR较高。DSC分析表明,GDA交联凝胶结合水含量较高。NMBA、GDA交联凝胶的Fick动力学参数n分别为0.462、0.267,说明GDA交联凝胶的溶胀过程偏离Fick模型。降解实验表明,GDA交联凝胶中PCL降解较慢。力学性能测试表明,GDA交联凝胶表现出较高的断裂强度和断裂伸长率。     

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.     

Crosslinking of gelatin-based drug carriers by genipin induces changes in drug kinetic profiles in vitro

Hydrogels are extensively studied as carrier matrices for the controlled release of bioactive molecules. The aim of this study was to design gelatin-based hydrogels crosslinked with genipin and study the impact of crosslinking temperature (5, 15 or 25°C) on gel strength, microstructure, cytocompatibility, swelling and drug release. Gels crosslinked at 25°C exhibited the highest Flory–Rehner crosslink density, lowest swelling ratio and the slowest release of indomethacin (Idn, model anti-inflammatory drug). Diffusional exponents (n) indicated non-Fickian swelling kinetics while drug transport was anomalous. Hydrogel biocompatibility, in vitro cell viability, cell cycle experiments with AH-927 and HaCaT cell lines indicated normal cell proliferation without any effect on cell cycle. Overall, these results substantiated the use of genipin-crosslinked hydrogels as a viable carrier matrix for drug release applications.     

Highly Elastic and Ultratough Hybrid Ionic–Covalent Hydrogels with Tunable Structures and Mechanics

Hybrid ionically–covalently crosslinked double‐network (DN) hydrogels are attracting increasing attention on account of their self‐recovery ability and fatigue resistance, but their relative low mechanical strength and tedious performance adjustment severely limit their applications. Herein, a new strategy to concurrently fabricate hybrid ionic–covalent DN hydrogels and modulate their structures and mechanics is reported, in which an in situ formed chitosan ionic network is incorporated by post‐crosslinking the chitosan‐based composite hydrogel using multivalent anions solutions. The obtained hybrid DN hydrogels exhibit predominant mechanical properties including superior elastic modulus, high tensile strength, and ultrahigh fracture energy because of the more efficient energy dissipation of rigid short‐chain chitosan network. Notably, the swollen hydrogels still remain mechanically strong and tough even after immersion in water for 24 h. More significantly, simply changing the post‐crosslinking time can vary the compactness and rigidity of the chitosan network in situ, achieving flexible and efficient modulation of the structures and mechanics of the hybrid DN hydrogels. This study opens up a new horizon in the preparation and regulation of DN hydrogels for promising applications in tissue scaffolds, actuators, and wearable devices.     

水凝胶对海洋生物附着的影响研究

研究了海带孢子在阴离子、阳离子、非离子型凝胶表面的附着及生长情况。结果表明,离子型凝胶比非离子型凝胶具有更好的防附着能力,其中聚氯化三甲基3 丙烯酰胺丙基胺凝胶和聚丙烯酸凝胶表面海带孢子的萌发率均为0,适合作为防附着材料。此外,离子型凝胶表面孢子的附着量受凝胶的交联度影响,而孢子的萌发率以及配子体的生长发育均与凝胶的交联度无关。     

Macroporous hydrogels based on 2-hydroxyethyl methacrylate

Four series of macroporous hydrogels based on crosslinked copolymers of 2-hydroxyethyl methacrylate (HEMA)-sodium methacrylate (MANa), copolymer HEMA-[2-(methacryloyloxy)ethyl]trimethylammonium chloride (MOETACl), terpolymer HEMA-MANa-MOETACl and on a polyelectrolyte complex were used as carriers for immobilization of proteins, chicken egg white albumin and avidin. The adsorption capacity of the hydrogels for the two proteins, kinetics and pH dependence of albumin adsorption and desorption were studied. The morphology of the hydrogels with and without immobilized albumin was studied by low-vacuum scanning electron microscopy.     

Properties and biocompatibility of chitosan films modified by blending with PVA and chemically crosslinked

In the present work we report the synthesis, characterization, and preliminary biocompatibility of polymer blends based on Chitosan and poly(vinyl alcohol) (PVA) with low degree of hydrolysis and chemically crosslinked by glutaraldehyde for potential application on skin tissue repairing. The microstructure and morphology of the blended hydrogels were characterized through Fourier Transform Infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM/EDX) analysis. Hydrogels were investigated by swelling as preliminary in vitro test using simulated body fluid. In addition, biocompatibility, cytotoxicity, and cell viability were assessed via MTT assay with VERO cell culture and cell spreading-adhesion analysis. It was found that by increasing the chitosan to PVA ratio, simulated body fluid uptake of the material was significantly altered. All the tested hydrogels have clearly presented adequate cell viability, non-toxicity, and suitable properties which can be tailored for prospective use in skin tissue engineering.     

Effect of the molecular weight of polyethylene glycol (PEG) on the properties of chitosan-PEG-poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide) hydrogels

Our prior study has shown that polyethylene glycol (PEG) played a crucial role in improving the properties of the physically crosslinked chitosan-PEG-poly(N-isopropylacrylamide) (PNIPAAm) hydrogels. In this paper, we further investigated the effect of the molecular weight (MW) of PEG on the properties of the chitosan-based physical hydrogels. Fourier Transform Infrared Spectroscopy (FTIR) study showed that the interaction between PEG and other components in the physically crosslinked hydrogels became stronger as the MW of PEG increased. The wide angle X-ray diffraction (WAXD) study indicated that the crystallinity of the physical hydrogels decreased with an increase in the MW of PEG. The thermal study using differential scanning calorimetry (DSC) revealed the crystallizability of the physical hydrogels first reduced with an increase in the MW of PEG, but slightly increased thereafter with a further increase in the MW of PEG. The swelling test showed the water uptake capability of the physical hydrogels increased with an increase in the MW of PEG. The results obtained by scanning electron microscope (SEM) found that the morphological changes of the physical hydrogels with MW of PEG were consistent with the results of swelling and thermal properties; and, contrary to pure PNIPAAm hydrogels which showed a compact and dense network structure at a temperature (37 degrees C) above its LCST, the physical chitosan-PEG-PNIPAAm hydrogels exhibited porous network structure at 37 degrees C instead. The mechanical property of the physical hydrogels was initially increased with an increase in PEG MW, but deteriorated with a further increase in PEG MW. Therefore, the MW of PEG played a key role in controlling the property of the chitosan-based physical hydrogels.     

Cooking‐Inspired Versatile Design of an Ultrastrong and Tough Polysaccharide Hydrogel through Programmed Supramolecular Interactions

Simultaneously achieving strength and toughness in soft materials remains a challenge, especially for physically crosslinked hydrogels with many inactive interaction sites. In this work, inspired by the cooking of thick soup in China, a facile method that includes free water evaporation of the diluted pregel solution followed by crosslinking (WEC) is proposed to fabricate polysaccharide hydrogels. Herein, without the constraints of viscosity and crosslinking, polymer chains can homogenously approach as much as possible, thereby enabling the transformation of inactive supramolecular interaction (H‐bonding and ionic coordination) sites into active sites until reaching the maximum level. Through facilely tuning the concentrating degree, programmed supramolecular interactions, serving as energy‐dissipating sacrificial bonds, impart the hydrogels with strength and toughness over a very wide range, where a “ductile‐to‐tough” transition is discovered to occur first. Using WEC in alginate, the concentration can be as high as 25 wt% without sacrificing processing ability, a result that is significantly beyond common value (3–7 wt%), and the extremely stiff and tough hydrogels are obtained, superior to isotropic alginate hydrogels ever reported. This research offers a facile and versatile strategy to fabricate isotropic polysaccharide hydrogels, which become ideal matrix materials for further fabrication of hybrid or anisotropic hydrogels.     

Preparation and characterization of stimuli-resistible hydrogels nano-coated with polyelectrolyte multilayer films

Alginate (ALG) hydrogels were nano-coated with polyelectrolyte multilayer (PEM) films composed of poly(diallyldimethyl ammonium chloride) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS). Non- and nano-coated ALG hydrogels were immersed into salt solutions (pH 6, ionic strength: 0.01 M), and the swelling behavior of these ALG hydrogels was observed by optical microscopy. The increases in the diameter of the 10-step coated ALG hydrogels were one fourth or less than that of the non-coated hydrogels. These results indicate that the characteristics of nano-coated ALG hydrogels remain unchanged independent of how the external environment is changed (e.g., pH, ionic strength). Consequently, tolerant ionic hydrogels may be prepared by the nano-coating of hydrogel surfaces with PEM films and may be useful for technological and biomedical applications.