温度及pH敏感共聚/粘土纳米复合水凝胶的合成与性能研究

以无机粘土为交联剂制备了具有温度、pH双重敏感性的聚（N-异丙基丙烯酰胺-co-甲基丙烯酸-β-羟乙酯）/粘土纳米复合水凝胶（P（NIPA-co-HEMA）/clay）,并用红外和X衍射对其结构和形态进行了表征。在弱碱性（pH=7.4）和25℃条件下,分别研究了温度和不同pH缓冲溶液对该凝胶溶胀度的影响,测定了纳米复合水凝胶的力学性能。结果表明：水凝胶的粘土已被剥离成单片层,且均匀分散在凝胶网络中,起交联作用;P（NIPA-co-HEMA）/clay具有良好的温度、pH双重敏感特性;凝胶的断裂伸长率〉1000%。     

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。     

壳聚糖接枝聚丙烯酸/石墨烯复合水凝胶的制备及表征

首先采用改进的Hummers法制备氧化石墨烯,将壳聚糖溶解在乙酸溶液中,后加入引发剂过硫酸钾和单体丙烯酸,引发丙烯酸发生接枝聚合,将丙烯酸接枝聚合到壳聚糖上得到壳聚糖接枝聚丙烯酸（CS-g-PAA）。将CS-g-PAA分散在蒸馏水中,加入石墨烯（GO）形成分散液,最后采用戊二醛交联得到CS-g-PAA/GO复合水凝胶。水凝胶呈现纤维状,直径为723±125 nm。CS-g-PAA:GO从3:1降低到1:1,水凝胶的孔隙率和比表面积分别为从94.33%和55.31 m2/g增加至96.12%和60.90 m2/g。体外凝血实验表明,CS-g-PAA和CS-g-PAA/GO水凝胶均可促进血液凝结,相比较纯的CS-g-PAA,复合水凝胶中引入GO后,水凝胶的血液凝固指数（BCI）从65.12%降低到40.19%。主要归因于GO促进血小板聚集和CS-g-PAA/GO具有更强的物理吸收能力的结合作用。CS-g-PAA/GO复合水凝胶有望成为理想的止血材料。     

PAM/SA/CNFs复合水凝胶的制备与性能研究

通过溶液交联聚合法制备了聚丙烯酰胺(PAM)/海藻酸钠(SA)/纤维素纳米纤维(CNFs)半互穿网络结构复合水凝胶。研究了不同添加量的CNFs对SA/PAM/CNFs复合水凝胶的溶胀性能和力学性能的影响;并测定了该复合水凝胶对亚甲基蓝染料的吸附性能。结果表明:当CNFs添加量为0.1ω/%时,复合水凝胶对亚甲基蓝染料的吸附效果最好,且平衡溶胀度最大为9.47,复合水凝胶压缩应力达到114.64 kPa。     

聚丙烯酸/氧化石墨烯复合水凝胶制备及对亚甲基蓝吸附

以丙烯酸(AA)为原料,二丙烯酸酯(Pul DA)分散的氧化石墨烯(GO)纳米胶粒(GO-Pul DA)为增强剂,N,N'-亚甲基双丙烯酰胺(BIS)为交联剂,通过自由基共聚合制备了一系列结构均一的聚丙烯酸/氧化石墨烯复合水凝胶(PAA/GO-Pul DA)。考察了BIS质量浓度、GO质量浓度以及溶液pH值对复合水凝胶力学性能、吸水性和亚甲基蓝(MB)吸附量的影响。结果表明,当GO质量浓度从0.1 g/L增加至1.0 g/L时,复合水凝胶拉伸强度从5.0 k Pa增加至10.4 k Pa,断裂伸长率高于100%,当GO的质量浓度为0.3 g/L时,复合水凝胶的断裂伸长率最高为151%;复合水凝胶表现出pH敏感的高吸湿性,pH从3.0增加至6.8时,平衡溶胀比(SRe)变化可达386 g/g,pH=6.8时最大SRe高达490 g/g。当溶液pH值从3.0增加至11.0时,PAA/GO-Pul D对MB的平衡吸附量(qe)可增加1 400~1 500 mg/g,pH=11.0时最大的qe高达1 789 mg/g。复合水凝胶对MB的吸附行为符合准一级动力学模型。5次吸附-解吸附循环后,相对于首次吸附,PAA/GO-Pul D对MB的吸附能力仍保持高达60%,解吸附效率高于90%。     

N-异丙基丙烯酰胺/甲基丙烯酸/氧化石墨烯复合水凝胶研究

以N-异丙基丙烯酰胺(NIPAM)和甲基丙烯酸(MAA)为单体,N,N-亚甲基双丙烯酰胺(BIS)为交联剂,过硫酸铵(APS)为引发剂,在氧化石墨烯(GO)水溶液中进行自由基原位聚合,制备了聚N-异丙基丙烯酰胺/聚甲基丙烯酸/氧化石墨烯(PNIPAM/PMAA/GO)复合水凝胶,研究了GO的含量变化对复合水凝胶性能的影响。结果表明,GO的加入能明显提高水凝胶的力学性能,复合水凝胶的平衡溶胀比随着GO含量的增加而降低,并且也具有优异的pH敏感性。     

化学交联法制备ZnO/PVA复合水凝胶

以氯化锌为原料制备纳米氧化锌(ZnO),采用化学交联法法制备ZnO/聚乙烯醇(PVA)复合水凝胶,研究ZnO加入量对复合水凝胶拉伸强度、断裂伸长率以及溶胀性能的影响。实验结果表明:ZnO含量为0.1%时,复合水凝胶的拉伸强度和断裂伸长率最大,而ZnO含量为0.4%时,复合水凝胶的溶胀率最大。     

n-HA/Ⅰ-Col/PVA复合水凝胶材料制备及其性能研究

本研究以纳米羟基磷灰石(n-HA)、聚乙烯醇(PVA)以及Ⅰ型胶原(Ⅰ-Col)为原料,通过物理共混法、表面活性剂OP-10发泡致孔法及化学-物理交联法制备纳米羟基磷灰石/Ⅰ型胶原/聚乙烯醇(n-HA/Ⅰ-Col/PVA)复合水凝胶,以期用于人工角膜支架材料.实验以化学交联剂戊二醛的用量、胶原用量作为变量来研究最佳配方.结果表明当加入4mL胶原和2mL 0.04 mol/L戊二醛时,复合水凝胶含水率为70.41％、孔隙率为58.95％、拉伸强度为3.87 MPa,具有较好的人工角膜综合性能;XRD与IR表明原材料与交联剂之间互相有物理-化学交联作用;SEM观察可见复合水凝胶呈多孔网状结构,孔洞之间相互贯通.     

纳米硅/聚丙烯酰胺水凝胶的制备及性能研究

通过光催化方法制备了纳米硅(F-SiNPs),再以丙烯酰胺(AM)为单体、过硫酸铵为引发剂、N,N-亚甲基双丙烯酰胺为交联剂,采用原位聚合法在纳米硅水溶液中制备了F-SiNPs/聚丙烯酰胺(F-SiNPs/PAM)复合水凝胶,并采用激光粒度分析仪(DLS)、场发射透射电子显微镜(FE-TEM)、红外光谱(FT-IR)、X射线光电子能谱(XPS)、场发射扫描电子显微镜(SEM)、紫外荧光光谱(UV-PL)等手段对复合水凝胶的结构与性能进行表征。结果表明,成功地制备了F-SiNPs/PAM复合水凝胶,且F-SiNPs/PAM复合水凝胶同时具有荧光特性与pH敏感性。     

PAA/PEG复合水凝胶膜的制备及其性能

以丙烯酸(AA)为单体、聚乙二醇(PEG)为大分子模板、N,N-亚甲基双丙烯酰胺为交联剂、过硫酸铵为引发剂,通过自由基溶液聚合法原位聚合制备了聚丙烯酸(PAA)/PEG复合水凝胶膜,研究了PEG用量对复合水凝胶成膜性、热稳定性、溶胀性能和力学性能的影响。结果表明:成功制备了PAA/PEG复合水凝胶膜;适量PEG的引入有利于复合水凝胶成膜;PAA/PEG复合水凝胶膜的热稳定性良好;PEG的引入对水凝胶膜的吸水溶胀性能不利;适量PEG有利于提高凝胶的力学性能,复合水凝胶膜软而韧;PEG与AA质量比为0.4的PAA/PEG复合水凝胶的拉伸强度和断裂标称应变最大,分别为1.58 MPa,414%。     

基于动态硼酸酯键/氢键的自修复水凝胶的制备及性能

通过4-(溴甲基)苯基硼酸(PBA)和1-乙烯基咪唑(IL)的烷基化反应制备了苯硼酸离子液体(PBA-IL)单体。在2,2,6,6-四甲基哌啶-1-氧自由基(TEMPO)氧化纳米纤维素(CNF)的存在下，通过丙烯酰胺(AM)和PBA-IL的一步聚合反应，制备了一种具有半互穿网络结构的自修复导电水凝胶(PAM/PBA-IL/CNF)。通过1HNMR对PBA-IL的化学结构进行表征；通过FTIR、XPS、SEM对水凝胶的化学结构和物理形貌进行表征，并测试了水凝胶的拉伸性能、自修复性能和导电性能。结果表明，PBA-IL单体和水凝胶成功制备，且水凝胶具有典型的多孔结构。PAM/PBA-IL3/CNF水凝胶[3代表PBA-IL含量为30%，以AM、PBA-IL、CNF悬浮液、N,N’-亚甲基双丙烯酰胺(MBA)溶液、过硫酸铵(APS)的总绝干质量为基准]的断裂应力为335.1 kPa、断裂伸长率为1969.5%、断裂能为12.1 kJ/m²、自修复效率为95.43%(150 min)、电导率为6.38 mS/cm。     

Preparation and characterization of PAM/SA tough hydrogels reinforced by IPN technique based on covalent/ionic crosslinking

In order to fabricate tough hydrogels with superior formability, polyacrylamide/sodium alginate (PAM/SA) interpenetrating polymer network (IPN) hydrogels were produced with ionically crosslinked SA interpenetrated in covalently crosslinked PAM. TGA results show that the heat resistance of PAM/SA IPN hydrogel is improved as compared to that of the individual component. Swelling studies indicate that increasing either chemical crosslinker content or ionic crosslinking via adding more N,N′‐methylenebisacrylamide (MBA) or SA results in lower ESR. It is concluded by tensile test that loosely crosslinked PAM coupled with tightly crosslinked SA improve mechanical strength for hydrogels based on covalent/ionic crosslinking. PAM/SA hydrogels via “one‐pot” method can form different complex shapes with mechanical properties comparable to conventional double network (DN) gels. The fracture strength of PAM_0.05/SA₂₀ reaches level of MPa, approaching 2.0 MPa. The work strives to provide method to tune mechanical and physical properties for hydrogels, which is hopefully to guide the design of hydrogel material with desirable properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41342.     

Nanocomposite carbon dots/PAM fluorescent hydrogels and their mechanical properties

In this work, the bio-friendly fluorescence carbon dots (CDs) which being fabricated by using α-D-lactose as carbon sources were successfully entrapped into the polyacrylamide (PAM) networks by atom transfer radical polymerization (ATRP) method at 50°C, which indicated a simple and versatile approach for a novel CDs/PAM composite hydrogel with both excellent mechanical and fluorescence properties. The HRSEM images exhibited that the CDs/PAM hydrogels have intensive microporous structure and uniformly distributed pores. The tensile and compressive mechanical properties of the CDs/PAM hydrogels with different weight ratios of AM/water (25%~50%)、MBA/AM (0.036%~0.18%) and CDs/water (0.0%~2.0%) were investigated, respectively. The results showed that when the weight ratios of AM/water at 47.6%, MBA/AM at 0.072% and CDs/water at 0.67wt%, the hydrogels exhibited optimized fracture strength at 161.4kPa and fracture stretch at 842.1%. In addition, with increasing weight ratios of the CDs/water from 0.0% to 2.0%, the CDs/PAM composite hydrogels exhibited higher fluorescence intensities and brighter blue fluorescent emission under the UV light excitation (300 nm). The excellent mechanical and fluorescence properties mean that they could be used as potentially optical visualization cartilage replacement materials in biomedical engineering fields.     

Glycerol-modified poly(vinyl alcohol)/poly(ethylene glycol) self-healing hydrogel for artificial cartilage

Poly(vinyl alcohol) (PVA) hydrogels have shown potential applications in bionic articular cartilage due to their tissue-like viscoelasticity, good biocompatibility and low friction. However, their lack of adequate mechanical properties is a key obstacle for PVA hydrogels to replace natural cartilage. In this study, poly(ethylene glycol) (PEG) and glycerol were introduced into PVA, and a PVA/PEG–glycerol composite hydrogel was synthesized using a mixing physical crosslinking method. The mechanical properties, hydrophilicity and tribological behavior of the PVA/PEG–glycerol hydrogel were investigated by changing the concentration of glycerol in PEG. The results showed that the tensile strength of the hydrogel reached 26.6 MPa at 270% elongation at break with 20 wt% of glycerol plasticizer, which satisfied the demand of natural cartilage. In addition, the excellent hydrophilicity of glycerol provides good lubricating properties for the composite gel under dry friction. Meanwhile, self-healing and cellular immunity assays demonstrated that the composite gel could have good self-healing ability and excellent biocompatibility even in the absence of external stimuli. This study provides a new candidate material for the design of articular cartilage, which has the potential to facilitate advances in artificial joint cartilage repair. © 2022 Society of Industrial Chemistry.     

干燥温度对纳米氧化石墨烯/PHBH复合膜结构及性能的影响

通过溶液浇铸法制备得到纳米氧化石墨烯（GO）/聚羟基丁酸-羟基己酸酯（PHBH）复合膜,利用SEM、XRD、DSC、拉伸测试、阻隔测试及透明度测试等检测手段,研究了不同干燥温度对复合膜结构及性能的影响,优化了制备工艺。结果表明：随着干燥温度的升高,GO在PHBH中的分散性以及复合膜的结晶度、断裂伸长率和阻隔性先增加后减小,而拉伸强度及透光率则随温度的增加而增加。当干燥温度为45℃→55℃梯度升温时,GO在PHBH中均匀分散,且复合膜的断面光滑,有良好的结晶度、热稳定性、力学及阻隔性能,其拉伸强度、断裂伸长率可分别达到20.11MPa、17.47%,且透氧系数及水蒸气透过系数分别为48cm³/(m²·d)、13.33g/(cm²·d),综合性能优于其他干燥温度下的复合膜。     

A Dual‐Crosslinked Strategy to Construct Physical Hydrogels with High Strength,Toughness, Good Mechanical Recoverability,and Shape‐Memory Ability

A novel type of physical hydrogel based on dual‐crosslinked strategy is successfully synthesized by micellar copolymerization of stearyl methacrylate, acrylamide, and acrylic acid, and subsequent introduction of Fe³⁺. Strong hydrophobic associations among poly(stearyl methacrylate) blocks form the first crosslinking point and ionic coordination bonds between carboxyl groups and Fe³⁺ serve as the second crosslinking point. The mechanical properties of the hydrogel can be tuned in a wide range by controlling the densities of two crosslinks. The optimal hydrogel shows excellent mechanical properties (tensile strength of ≈6.8 MPa, elastic modulus of ≈8.0 MPa, elongation of ≈1000%, toughness of 53 MJ m^?3) and good self‐recovery property. Furthermore, owing to stimuli responsiveness of physical interaction, this hydrogel also shows a triple shape memory effect. The combination of two different physical interactions in a single network provides a general strategy for designing of high‐strength hydrogels with functionalities.     

Fabrication of tough,self-recoverable,and electrically conductive hydrogels by in situ reduction of poly(acrylic acid) grafted graphene oxide in polyacrylamide hydrogel matrix

Developing electrically conductive hydrogels with good electronic properties and excellent mechanical performance is significant to their potential applications. In this article, we present a strategy to fabricate tough, self-recoverable and electrically conductive hydrogels containing reduced graphene oxide (rGO). Poly(acrylic acid) grafted graphene oxide (GO-g-PAA) was synthesized and incorporated into chemically crosslinked polyacrylamide (PAM) networks to obtain GO-g-PAA/PAM hydrogels, which were further treated with ascorbic acid solution at ambient temperature to give rGO-g-PAA/PAM hydrogels. The interfacial interaction between GO/rGO and hydrogel matrix was improved by reversible hydrogen bonds between the grafted PAA chains and PAM matrix. Consequently, both GO-g-PAA/PAM and rGO-g-PAA/PAM hydrogels exhibited improved tensile properties, excellent energy dissipation, and rapid self-recovery. The in situ chemical reduction of GO-g-PAA in hydrogel matrix endowed rGO-g-PAA/PAM hydrogels with satisfactory electrical conductivity and obvious resistance change upon stretching. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48781.     

Ultrastretchable,Super Tough,and Rapidly Recoverable Nanocomposite Double‐Network Hydrogels by Dual Physically Hydrogen Bond and Vinyl‐Functionalized Silica Nanoparticles Macro‐Crosslinking

It remains a challenge to develop tough hydrogels with recoverable or healable properties after damage. Herein, a new nanocomposite double‐network hydrogel (NC‐DN) consisting of first agar network and a homogeneous vinyl‐functionalized silica nanoparticles (VSNPs) macro‐crosslinked polyacrylamide (PAM) second network is reported. VSNPs are prepared via sol‐gel process using vinyltriethoxysilane as a silicon source. Then, Agar/PAM‐SiO₂ NC‐DN hydrogels are fabricated by dual physically hydrogen bonds and VSNPs macro‐crosslinking. Under deformation, the reversible hydrogen bonds in agar network and PAM nanocomposite network successively break to dissipate energy and then recombine to recover the network, while VSNPs in the second network could effectively transfer stress to the network chains grafted on their surfaces and maintain the gel network. As a result, the optimal NC‐DN hydrogels exhibit ultrastretchable (fracture strain 7822%), super tough (fracture toughness 18.22 MJ m^‐3, tensile strength 431 kPa), rapidly recoverable (≈92% toughness recovery after 5 min resting at room temperature), and self‐healable (can be stretched to 1331% after healing) properties. The newly designed Agar/PAM‐SiO₂ NC‐DN hydrogels with tunable network structure and mechanical properties by multi‐bond crosslinking provide a new avenue to better understand the fundamental structure‐property relationship of DN hydrogels and broaden the current hydrogel research and applications.