高强度水凝胶的制备及其研究进展

水凝胶因其拥有较高的溶胀比和极高的含水率,被广泛应用于各种领域,但力学性能较弱的缺点限制了其在组织工程、软体机器人、可穿戴电子设备等高负载领域的发展。综述了近年来纳米复合水凝胶、双网络水凝胶、大分子微球复合水凝胶、疏水缔合水凝胶等高强度水凝胶的制备方法及研究进展;讨论了各类型高强水凝胶的特点并指出了目前研究中存在的问题;同时,对高强度水凝胶未来的研究方向进行了展望。     

Poly(DMAEMA-co-VP)/Fe_3O_4纳米复合水凝胶的制备及性能

以甲基丙烯酸-N,N-二甲氨基乙酯(DMAEMA)、4-乙烯基吡啶(VP)为单体,N,N-亚甲基双丙烯酰胺(BIS)为交联剂,在Fe_3O_4纳米粒子分散液中原位共聚制备了具有温度、pH、磁场三重响应性的纳米复合水凝胶。对纳米复合水凝胶的溶胀性能、温敏性、pH敏感性、磁场响应性等性能进行了研究,进而考察了纳米复合水凝胶对重金属离子(Cu~(2+))的吸附脱附行为。结果表明,纳米复合水凝胶具有良好的温敏性、pH敏感性和磁场响应性,并且对重金属离子(Cu~(2+))有可逆的吸附-脱附作用。     

高强度耐低温纳米纤维素/聚乙烯醇导电复合水凝胶制备及其在柔性传感中的应用

纳米纤维素具有大长径比、较高的弹性模量与比表面积及丰富的表面官能团,是一种优良的纳米增强材料。首先以纳米纤维素(CNFs)为分散介质辅助分散MXene纳米片层,制备CNF-MXene纳米复合物,并通过FTIR与XPS分析CNFs与MXene的相互作用。以此复合物为增强填料,聚乙烯醇(PVA)为基底,制备CNF-MXene/PVA复合水凝胶,进一步通过KOH溶液处理,提高复合水凝胶的力学性能,并赋予复合水凝胶优异的离子导电性。该复合水凝胶表现出优异的力学性能,其拉伸强度与断裂伸长率分别达到255.9 kPa与1098.2%,还具有高电导率(2.38 S/m)、一定的抗冻性能与灵敏的应变/压力响应性。基于该复合水凝胶组装的应变/压力柔性传感器,由于具有极低的检测极限质量(100 mg)与极快的响应时间(225 ms),可以监控脉搏跳动与喉咙发声微小震动引起的压力变化。因此,该复合水凝胶基柔性传感器非常有希望应用于未来新一代可穿戴电子、人机交互等领域。      

纳米细菌纤维素/聚乙烯醇复合水凝胶在模拟体液中的疲劳行为

聚乙烯醇(PVA)复合水凝胶作为半月板及软骨等长期承重植入体,在生理环境中的疲劳行为关系到植入体的持久性和稳定性。采用弥散增强的方法将纳米细菌纤维素(BC)均匀分散在PVA水凝胶基体中,制备了纳米BC/PVA复合水凝胶。在模拟体液(SBF)环境中,采用压缩疲劳过程分析、疲劳前后刚度变化分析及疲劳前后尺寸稳定性分析3种方法,测试和评价了复合水凝胶的抗疲劳性能和力学稳定性。结果表明:纳米BC/PVA复合水凝胶在模拟人体环境中具有良好的抗疲劳性能,能够满足体内植入物的抗疲劳性能需求;纳米BC的加入可以有效提升复合水凝胶的力学稳定性和抗疲劳性能,但随着纳米BC含量的进一步升高,复合水凝胶的抗疲劳性能有所减弱,当PVA与纳米BC质量比为30∶1时,纳米BC/PVA复合水凝胶疲劳前期与后期最大位移变化量最小(0.002mm),疲劳前后刚度变化最小(5.41%),且疲劳前后尺寸稳定性最强,变形量仅为0.427mm,抗疲劳性能达到最佳。     

有机复合水凝胶的研究进展

有机复合水凝胶由于具有许多独特的性能而得到广泛应用。但由于传统水凝胶在力学性能、热性能、响应速率和生物相容性等方面存在缺陷,限制了它作为新材料的应用前景。使用有机分子对水凝胶进行复合改性已成为近年来水凝胶研究领域的热点课题之一。本文综述了近年来有机复合水凝胶的研究进展,从材料的制备、性能和潜在的应用领域进行了阐述,并对其未来发展进行了展望。     

高强度Poly(AM-co-IA)/Al_2O_3纳米复合水凝胶的制备及形状记忆行为EI北大核心CSCD

以氧化铝(Al_2O_3)纳米粒子作为无机交联剂,丙烯酰胺(AM)和衣康酸(IA)为单体,原位自由基聚合制备了高强度PAI/Al_2O_3纳米复合水凝胶,并提出了水凝胶的交联机理。对纳米复合水凝胶的力学性质、微观结构和溶胀性质进行了表征。结果表明,制备的水凝胶具有优异力学性能,拉伸和压缩强度分别可达477 k Pa和13.45 MPa。此外,PAI/Al_2O_3纳米复合水凝胶还表现出透明的外观,规整的网络结构,较低的溶胀率以及水驱动的形状记忆行为。因此,这种水凝胶在生物医学领域有广阔的应用前景。     

高强度Poly(AM-co-IA)/Al_2O_3纳米复合水凝胶的制备及形状记忆行为

以氧化铝(Al_2O_3)纳米粒子作为无机交联剂,丙烯酰胺(AM)和衣康酸(IA)为单体,原位自由基聚合制备了高强度PAI/Al_2O_3纳米复合水凝胶,并提出了水凝胶的交联机理。对纳米复合水凝胶的力学性质、微观结构和溶胀性质进行了表征。结果表明,制备的水凝胶具有优异力学性能,拉伸和压缩强度分别可达477 k Pa和13.45 MPa。此外,PAI/Al_2O_3纳米复合水凝胶还表现出透明的外观,规整的网络结构,较低的溶胀率以及水驱动的形状记忆行为。因此,这种水凝胶在生物医学领域有广阔的应用前景。     

导电复合水凝胶的分类及其在柔性可穿戴设备中的应用

近年来，基于水凝胶的导电材料及其作为柔性可穿戴设备的应用引起了人们的广泛关注。柔性可穿戴设备不仅可以采集人体生理信号用于远程健康监测，还在人机界面、软机器人等方面展示出巨大的应用潜力。导电水凝胶所具有的良好导电性、高延伸性、可调柔韧性、生物兼容性和多重刺激响应性等优点使其成为制备柔性可穿戴设备的理想材料。到目前为止，各种导电材料被广泛用于制作导电复合水凝胶。本文根据导电材料对导电复合水凝胶进行分类，包括离子导电水凝胶(基于盐离子、离子液体、聚电解质等导电物质)、电子导电水凝胶(基于导电聚合物基、碳材料、MXene和金属等导电物质)两大类，并介绍了导电水凝胶在人体运动监测、健康监测、人机界面等柔性可穿戴设备中的应用进展。     

羟基磷灰石纳米纤维增强甲基丙烯酸酐改性明胶复合水凝胶的制备及性能

采用溶剂热法制备了具有超高长径比的羟基磷灰石(HAP)纳米纤维,并将其与甲基丙烯酸酐改性明胶(GelMA)结合,利用紫外光交联制备了HAP纳米纤维/GelMA复合水凝胶。通过SEM、XRD、力学测试、溶胀测试、降解测试、细胞培养等对HAP纳米纤维/GelMA复合水凝胶进行结构表征和性能测试。SEM断面观察表明,HAP纳米纤维/GelMA水凝胶呈三维孔隙贯通的多孔结构。力学实验表明,HAP纳米纤维能有效增强水凝胶的弹性模量,且随着HAP纳米纤维添加量的增加,力学性能增强效果越明显。溶胀实验表明,当HAP纳米纤维质量分数为5.2wt%~14.2wt%时,HAP纳米纤维复合水凝胶的溶胀率变化不明显,当质量分数为18.2wt%时,溶胀率降低。降解实验表明,HAP纳米纤维的加入能有效保持水凝胶结构形态,使其更加稳定可控。细胞包裹培养实验表明,HAP纳米纤维/GelMA复合水凝胶能为细胞提供良好的三维生长环境,表现出优良的生物相容性。本实验制备的HAP纳米纤维/GelMA复合水凝胶在组织工程领域有着良好的应用前景。      

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。     

染料包覆胶态银纳米粒子掺杂的有机复合膜的制备与光吸收特性

为避免传统的湿化学法制备纳米掺杂复合材料中热处理给材料性能带来的负面影响,提出了一种简易可行的工艺方法:通过胶体化学法制备出稳定的胶态银纳米粒子分散系,以它为纳米粒子来源,使有机染料罗丹名6G(R6G)分子包覆到银纳米胶粒表面,将该胶体分散系均匀掺杂到明胶溶液中,制备出染料包覆胶态银纳米粒子掺杂的有机复合膜.本工作成功地制备出无机/有机活性基元掺杂的三元系复合膜,实现了染料分子对金属纳米粒子完全意义上包覆的设想和对活性基元的室温包埋工艺.电镜(TEM)观测了复合膜的显微结构,对复合膜的UV-Vis吸收光谱进行了测量.给出了一种包覆掺杂的结构模型,并用该模型成功地解释了实验结果.     

Effect of silver nanoparticles content on the various properties of nanocomposite hydrogels by in situ polymerization

A series of nanocomposite hydrogels (APEAg series gels) were prepared from acrylic acid, poly(ethylene glycol) methyl ether acrylate, and silver nanoparticles through in situ polymerization by UV irradiation. The effect of the content of silver nanoparticle on the properties of the nanocomposite hydrogels was investigated. Results showed that, with increasing of the content of the silver nanoparticle in the hydrogels, the crosslinking density and shear modulus of the hydrogel were not obviously changed, the electrical conductivities of the nanocomposite hydrogels increased, and their initial rate of Escherichia coli inactivation significantly increased, but their adhesive force only slightly decreased. These materials can be assessed as promising bioadhesive patch or wound-dressing material or electrical massage patch.     

Preparation of the Silver-Superconductor Composite by Deposition of the Silver Nanoparticles in the Bismuth Cuprate Superconductor

BiSCCO (Bi–Sr–Ca–Cu–O) is high temperature superconductor with a lot of possible applications. Interfaces between superconductors and metal conductors are one of the technological problems. In this work, silver-superconductor composite was prepared by using flow of silver nanoparticles suspension in DMF (N,N-dimethylformamide) through superconductor’s pore system. Silver nanoparticles were prepared by reaction of silver nitrate with DMF. Properties of prepared composite were measured by SEM charting, XRD and critical current measurements. SEM chart showed uniform distribution of silver across sample. XRD and critical current measurements validated superconducting properties of prepared composite. In the future, materials based on this method could be used as an interface between superconductors and metals or as a base for superconducting composite with much better mechanical properties.     

氧化石墨烯/壳聚糖层层自组装复合膜的制备及其在环保领域中的应用

利用层层自组装技术将氧化石墨烯与壳聚糖进行自组装,制备出一种新型的氧化石墨烯/壳聚糖复合膜,并利用原位合成的方法引入纳米银粒子。采用紫外可见光谱(UV-Vis)、红外光谱(FTIR)、X射线衍射(XRD)和原子吸收等分析方法对复合膜的自组装行为和催化性能进行了研究。实验结果表明,氧化石墨烯与壳聚糖可通过层层自组装技术制备出新型复合膜,这种复合膜可包裹纳米银粒子,膜内纳米银粒子对4-硝基苯酚的催化活性较高,并且可实现循环使用。此外,在稳定性实验中,复合膜不会释放纳米银粒子或银离子,避免了给水体带来二次污染。因此,这种材料在水处理等环保领域中可能具有巨大的潜在实用价值。     

Composite inks of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate)/silver nanoparticles and electric/optical properties of inkjet-printed thin films

Poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate)/silver nanoparticles composite inks have been prepared through in situ synthesis and ultrasonic dispersion. The developed inks were proved to be suitable for various inkjet printing trials to deposit the thin films which were subsequently characterized to assess their electric and optical properties. The results have indicated that the dedoping of PSS from PEDOT during the in situ synthesis can be detrimental to the conductivity of the deposited composite films. However, the addition of silver nanoparticles to pristine PEDOT:PSS has significantly enhanced the conductivity of the thin films, with an inevitable loss in transparency. The various factors that can influence the properties of the thin films have also been analyzed and discussed. This study provides an insight into the effect of silver nanoparticles on PEDOT:PSS thin films deposited using inkjet printing process, and their properties due to the methods of ink formulation.     

纳米银/壳聚糖复合水凝胶的原位制备、表征及抗菌性能研究

在壳聚糖/1,2-丙二醇凝胶中采用抗坏血酸原位还原硝酸银生成纳米银,进而通过碱液置换得到具有不同纳米银含量的物理交联的纳米银/壳聚糖复合水凝胶.紫外-可见光谱、X射线衍射图谱和低分辨率TEM照片的结果表明,复合水凝胶内形成了分散良好的纳米银.高分辨率TEM照片结果表明纳米银的直径在20～50nm之间,但其结晶状态并不均一.抗菌性实验证明,纳米银/壳聚糖复合水凝胶对大肠杆菌和金黄色葡萄球菌均有抗菌效果.     

天然石墨-纳米银/聚氨酯导电复合薄膜的制备及性能

采用热处理还原银盐原位引入银粒子的方法, 成功制备了天然石墨-纳米银/聚氨酯(C-Ag/PU)导电复合薄膜。并通过透射电镜(TEM)、 扫描电镜(SEM)观察了该复合薄膜的微观结构, 用X射线衍射仪(XRD)跟踪了银的还原和银粒子的生长过程, 探讨了加热温度和加热时间对银还原过程的影响, 研究了纳米银的生成和聚集对C/PU复合体系导电性能的影响。结果表明, 随着热处理的进行, 银粒子不断地生成和聚集, 最终以纳米尺寸(约10nm)均匀分散在聚合物基体中。纳米银粒子在天然石墨粒子之间起到了桥梁的作用, 改善了复合体系的导电通路, 显著提高了复合体系的导电性。      

Colored and functional silver nanoparticle-wool fiber composites

Silver nanoparticles utilizing the surface plasmon resonance effect of silver have been used to color merino wool fibers as well as imparting antimicrobial and antistatic properties to them to produce a novel silver nanoparticle-wool composite material. This is accomplished by the reduction of silver ions in solution by trisodium citrate (TSC) in the presence of merino wool fibers or fabrics. The silver metal nanoparticles simultaneously bind to the amino acids of the keratin protein in the wool fibers using TSC as the linker. The colors of the resulting merino wool-silver nanoparticle composites range from yellow/brown to red/brown and then to brown/black, because of the surface plasmon resonance effect of silver, and are tuned by controlling the reduction of silver ions to silver nanoparticles to give the required particle size on the fiber surface. In addition to the surface plasmon resonance optical effects, the silver nanoparticle-wool composites exhibit effective antimicrobial activity, thus inhibiting the growth of microbes and also an increase in the electrical conductivity, imparting antistatic properties to the fibers. Therefore, silver nanoparticles function as a simultaneous colorant and antimicrobial and antistatic agent for wool. Chemical and physical characterizations of the silver nanoparticle-merino wool composite materials have been carried out using scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, synchrotron radiation X-ray diffraction, atomic absorption spectroscopy, X-ray photoelectron spectroscopy, direct-current electrical conductivity measurements, wash-fast and rub-fast tests, and antimicrobial tests.     

Effect of silane-based coupling agent on the properties of silver nanoparticles filled epoxy composites

The study aims at investigating package materials based on combinations of nanometallic particles and polymers for microelectronics. Understanding the behaviors of this combination materials and being able to tailor them to give a desired composite properties are of great importance. In this present study, silver nanoparticles (Ag) were used as metallic conductive filler and it was applied in epoxy resin to produce silver nanoparticles filled epoxy composites. The electrical and flexural properties of silver nanoparticles-filled epoxy composites, as functions of filler loading (0–8 vol.%) were investigated. Furthermore, study on the effect of silane coupling agent treatment on the electrical and flexural properties of Ag nanoparticles-filled epoxy composites was carried out. The electrical property characterization indicates that the insulator-to-conductor transition occurred at percolation threshold of 5 vol.% of Ag. Treatment of Ag by silane-based coupling agent exhibited remarkable improvement in electrical and flexural properties of the composite system. Morphological studies have shown noticeable improvement in filler dispersivity in the treated composite system compared to those untreated system. FTIR analysis indicates the existence of –Si–O–C–, C–N and Si–H silane bonding in the treated composites, which subsequently improve the adhesion and enhance the electrical and flexural properties of the treated composite system.     

Effects of filler shape and size on the properties of silver filled epoxy composite for electronic applications

Epoxy composites filled with nano- and micro-sized silver (Ag) particulate fillers were prepared and characterized based on flexural properties, coefficient of thermal expansion, dynamic mechanical analysis, electrical conductivity, and morphological properties. The influences of these two types of Ag fillers, especially in terms of their sizes and shapes, were investigated. Silver nanoparticles were nano-sized and spherical, while silver flakes were micron-sized and flaky. It was found that the flexural strength of the epoxy composite filled with silver flakes decreased, while the flexural strength of the epoxy composite filled with silver nanoparticles showed an optimum value at 4 vol.% before it subsequently dropped. Both silver composites showed improvement in flexural modulus with increasing filler loads. CTE value indicated significant decrements in filled samples compared to neat epoxy. Results on the electrical conductivity of both systems showed a transition from insulation to conduction at 6 vol.%.