白炭黑原位复合聚丙烯酰胺水凝胶的合成及次级网络对流变行为的影响

采用水溶液聚合法,通过丙烯酰胺与白炭黑原位复合,制备出复合聚丙烯酰胺凝胶.采用高级流变仪和红外吸收光谱证实了白炭黑与聚丙烯酰胺形成的次级网络的存在,通过对比不同白炭黑填充量和不同吸水倍数对聚丙烯酰胺水凝胶模量、损耗角正切、零切黏度和流动指数的影响,发现白炭黑的加入对聚丙烯酰胺凝胶力学性能的贡献,随着白炭黑用量在0%～3...     

Self‐Sealed Bionic Long Microchannels with Thin Walls and Designable Nanoholes Prepared by Line‐Contact Capillary‐Force Assembly

Long microchannels with thin walls, small width, and nanoholes or irregular shaped microgaps, which are similar to capillaries or cancerous vessels, are urgently needed to simulate the physiological activities in human body. However, the fabrication of such channels remains challenging. Here, microchannels with designable holes are manufactured by combining laser printing with line‐contact capillary‐force assembly. Two microwalls are first printed by femtosecond laser direct‐writing, and subsequently driven to collapse into a channel by the capillary force that arises in the evaporation of developer. The channel can remain stable in solvent due to the enhanced Van der Waals' force caused by the line‐contact of microwalls. Microchannels with controllable nanoholes and almost arbitrary patterns can be fabricated without any bonding or multistep processes. As‐prepared microchannels, with wall thicknesses less than 1 µm, widths less than 3 µm, lengths more than 1 mm, are comparable with human capillaries. In addition, the prepared channels also exhibit the ability to steer the flow of liquid without any external pump.     

Hydrogel Paint

For a hydrogel coating on a substrate to be stable, covalent bonds polymerize monomer units into polymer chains, crosslink the polymer chains into a polymer network, and interlink the polymer network to the substrate. The three processes—polymerization, crosslinking, and interlinking—usually concur. This concurrency hinders widespread applications of hydrogel coatings. Here a principle is described to create hydrogel paints that decouple polymerization from crosslinking and interlinking. Like a common paint, a hydrogel paint divides the labor between the paint maker and the paint user. The paint maker formulates the hydrogel paint by copolymerizing monomer units and coupling agents into polymer chains, but does not crosslink them. The paint user applies the paint on various materials (elastomer, plastic, glass, ceramic, or metal), and by various operations (brush, cast, dip, spin, or spray). During cure, the coupling agents crosslink the polymer chains into a network and interlink the polymer network to the substrate. As an example, hydrogels with thickness in the range of 2–20 µm are dip coated on medical nitinol wires. The coated wires reduce friction by eightfold, and remain stable over 50 test cycles. Also demonstrated are several proof‐of‐concept applications, including stimuli‐responsive structures and antifouling model boats.     

酶响应水凝胶研究进展

本文简要介绍了环境响应型水凝胶的研究现状,重点分析了酶响应水凝胶,包括谷氨酰胺转氨酶、激酶与磷酸酶、酪氨酸酶、枯草杆菌蛋白酶与嗜热菌蛋白酶、过氧化物酶、酯酶与核酸内切酶等引起水凝胶响应的酶因素,并介绍了酶响应引起自组装的形成、自组装的破坏以及动态自组装等材料响应。此外,分析了酶响应水凝胶研究中存在的问题,并介绍了肽水凝胶的生物学功能。     

光交联透明质酸水凝胶的制备及性能

采用甲基丙烯酸缩水甘油酯(GMA)对透明质酸(HA)进行化学改性,然后在紫外辐射下交联成水凝胶。随着GMA与HA物质的量比的增加(分别为10、20和50),HA分子链上的GMA取代度分别为2.8%、16.9%和45.2%,由此制得的水凝胶其交联点间平均分子质量分别为9.33×105g/mol、7.95×105g/mol、6.54×105g/mol;水凝胶的内部孔径逐渐变小;水凝胶的存储模量(G′)分别为70 Pa、101 Pa和160Pa,损耗模量(G″)分别为6.6 Pa、7.8 Pa和12.6 Pa;水凝胶的降解失重速率逐渐减慢,在120h时的失重百分率分别为63%、39.4%和30.8%。结果表明,GMA与HA物质的量比的增加有利于水凝胶交联密度的提高,力学性能的增强和降解速率的降低。     

Patterning Porous Oxides within Microchannel Networks

A continuing challenge for materials chemists and engineers is the ability to create multifunctional composite structures with well‐defined superimposed structural order from nanometer to micrometer length scales. Materials with three‐dimensional structures ordered over multiple length scales can be prepared by carrying out colloidal crystallization and inorganic/organic cooperative self‐assembly within microchannel networks. The resulting materials show hierarchical ordering over several discrete and tunable length scales ranging from several nanometers to micrometers. These patterned porous materials hold promise for use as advanced catalysts, sensors, low‐k dielectrics, optoelectronic and integrated photonic crystal devices.     

Optically Coated Mirror‐Embedded Microchannel to Measure Hydrophoretic Particle Ordering in Three Dimensions

Three‐dimensional (3D) measurement of the behavior of microfluidic particles is vital for improving their operational efficiency and characterization. In particular, it is important to measure particle motions in 3D for exact characterization of hydrophoresis, which utilizes 3D convective flows for size separation. Herein, the 3D measurement of hydrophoretic particle ordering for the exact characterization of hydrophoresis by using an optically coated mirror‐embedded microchannel is reported. The mirror, ideally at 45°, reflects the side view of the channel and enables 3D positional information to be obtained easily from two different orthogonal‐axis images. With this method, it is shown that hydrophoresis is governed by convective vortices and steric hindrance. It is also observed that hydrophoresis enables 3D particle focusing without sheath flows and accurate flow‐rate control. The mechanism of hydrophoresis is finally verified by conducting a computational simulation and comparing the simulation results with the experimental measurements. The hydrophoretic method can be straightforwardly integrated as a 3D particle‐focusing component in integrated microfluidic systems. The mirror‐embedded channel can also be readily fabricated in a single cast of polydimethylsiloxane, thus offering low‐cost, easy implementation of 3D particle measurement.     

光响应高分子凝胶的研究与进展

光响应高分子凝胶是智能高分子凝胶中的一种,近年来备受世界各国科学家的重视.综述了近年来光响应智能高分子凝胶材料的最新研究进展,具体介绍了光响应高分子凝胶的光响应机理、种类及目前的应用研究状况,并展望了其未来的应用研究与发展.     

双螺杆挤出法制备聚乙烯醇水凝胶及其表征

采用双螺杆挤出工艺并经过反复冷冻-解冻法制备聚乙烯醇(PVA)/纯水和PVA/二甲基亚砜(DM SO)/H2O凝胶。利用静态拉伸实验和动态力学分析对样品的力学性能进行了测试。结果表明,双螺杆挤出法制备的凝胶拉伸强度高于溶液浇铸法所得样品的拉伸强度。动态力学分析方法(DM A)研究表明,相同PVA浓度下,混合溶剂体系m(DM SO)/m(H2O)=80/20的弹性模量大于纯水体系。理论计算了两种凝胶的有效交联密度(eυ)和网链分子量(Mc)。对两种凝胶动态力学行为进行了分析讨论,PVA/H2O和PVA/DM SO/H2O的模量和力学损耗(tanδ)随温度升高有不同的转变行为。     

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。     

Flexible All-in-one Quasi-Solid-State Batteries Enabled by Low-water-content Hydrogel Films

The high conductivities and good mechanical properties of hydrogel electrolyte films are critical for energy storage devices with high flexibility, fast redox kinetics, and long life. Herein, a low water content (6.63 wt%) hydrogel film is prepared, and a favorable environment is created, with an electrochemical stability window of 2.26 V and a high ionic conductivity of 2.6 mS cm⁻¹. The hydrogel film exhibits good folding ability, low in-plane swelling, and anti-freezing abilities. These properties are benefitted by immobilizing free water molecules on the abundant oxygenic groups of polymer fibers in the hydrogel film, offering a unique 3D channel to allow Li⁺ to quickly transport along the polymer network. Therefore, the hydrogel film-based all-in-one flexible cell exhibits stable cycling performance with a retention of 81.8% of the initial capacity after 500 cycles at room temperature and 66.2% of capacity retention at −30 °C. Furthermore, the full cell with high cathode loading (≈21 mg cm⁻²) exhibits a high areal capacity of 2.5 mAh cm⁻² (≈119 mAh g⁻¹). The overall merits of flexible all-in-one quasi-solid-state batteries demonstrate high potential to be used for power wearable electronics.     

阳离子化壳聚糖水凝胶电刺激响应行为

通过将壳聚糖季铵盐化改性并交联制备了一种新型阳离子化壳聚糖水凝胶,研究了凝胶的溶胀性能和电刺激响应行为。结果表明,该凝胶在NaCl溶液中其平衡溶胀率随NaCl离子强度的增大而减小。在NaCl溶液中于非接触直流电场作用下,该凝胶向电场正极弯曲,弯曲速度和应变随外加电压的增大而增大,并随NaCl离子强度的增大到0.15处出...     

NVP共聚物水凝胶中吸附水的性能研究

以N-乙烯基吡咯烷酮、甲基丙烯酸羟乙酯及甲基丙烯酸丁酯为单体,共聚制备了两种水凝胶材料,并采用重量法和热失重法研究了这两种不同组成水凝胶对其吸附水性能的影响。研究结果表明:加入疏水性单体甲基丙烯酸丁酯,使水凝胶的交联度加大,改变了水凝胶的结构,水凝胶的吸水性及吸水速率下降,而保水性提高,即脱水速率减慢。     

温度敏感型PCL-Pluronic-PCL水凝胶的合成与性能

通过泊洛沙姆(Pluronic)引发己内酯(ε-CL)开环反应,合成了一种较低分子量的PCL-Pluronic-PCL多嵌段共聚物,并采用FT-IR和1H-NMR对其结构进行表征。这种PCL-Pluronic-PCL共聚物有良好的水溶性,并且当其水溶液浓度高于临界凝胶浓度(CGC)时,随着温度的变化呈现出凝胶-溶胶转变特性。采用试管法测试共聚物水溶液的凝胶-溶胶转变。该共聚物水凝胶在可注射药物控制释放系统等方面有着广泛的潜在应用价值。     

壳聚糖/聚乙烯醇水凝胶的硬度研究

探讨了壳聚糖/聚乙烯醇水凝胶的制备方法,研究了聚乙烯醇与壳聚糖质量比、溶剂醋酸溶液体积、交联剂戊二醛浓度等对水凝胶硬度的影响.正交实验结果表明当聚乙烯醇与壳聚糖质量比为6、溶剂醋酸体积为80mL、交联剂戊二醛浓度为0.426mol/L时,凝胶硬度为132.643kPa.凝胶硬度随着聚乙烯醇与壳聚糖质量比和交联剂戊二醛浓度的增大而增大,随着溶剂醋酸溶液体积的增加而减小,随着凝胶温度的升高先增大后减小,壳聚糖/聚乙烯醇凝胶硬度随着放置时间的延长而逐渐增大,PVA-124与壳聚糖制备的凝胶硬度最大.     

天然生物质水凝胶吸附材料研究进展

生物质资源产量大,但是利用效率不高,将其制备成高吸附性水凝胶不仅可消除环境污染,减少资源浪费,还可以有效地降低成本。综述了近年来天然生物质功能性水凝胶的制备原料及其制备方法,重点概述了水凝胶在重金属离子和染料吸附方面的应用,总结并展望了生物质凝胶的重点研究方向和未来发展前景。     

壳聚糖/羟丙基甲基纤维素温敏水凝胶的制备

采用壳聚糖(CS)、羟丙基甲基纤维素(HPMC)为原料制备了温敏性水凝胶,分析了CS含量、HPMC含量、HPMC黏度和甘油添加量对CS/HPMC的低临界溶解温度的影响。最优条件为CS含量为1%(m/V),HPMC的黏度为6 m Pa·s,HPMC的含量为7%(m/V),甘油含量为32%(m/V),得到体系的低临界溶解温度为32℃,体系的黏度为1407 m Pa·s。红外光谱测试表明CS、HPMC与甘油之间没有化学作用,流变性测试显示体系可以在36℃下凝胶化。MTT测试结果表明CS/HPMC/Gyl无毒副作用,具有良好的生物相容性。研究结果表明该体系是一种良好的可注射型温敏水凝胶。     

水凝胶角膜接触镜材料研究进展

以角膜接触镜材料的基本要求为出发点,在相关文献和专利的基础上综述了目前软性亲水的水凝胶角膜接触镜材料的研究进展及发展趋势.特别针对传统型水凝胶角膜接触镜的透氧和均一成分构建的局限,分别重点介绍了高透氧角膜接触镜材料及互穿网络角膜接触镜材料.前者通过引入硅氧烷成分使角膜接触镜的延长配戴成为可能,后者则通过交联互锁的结构实现了材料的均一性和稳定性,从而为角膜接触镜材料在药物释放和治疗用途上的更广泛应用创造了条件.