具有快速响应特性的环境响应型智能水凝胶的研究进展

环境响应智能水凝胶应用于化学传感器、化学微阀、人造肌肉、药物控释载体、物质分离等领域时常常需要快速响应特性,提高智能水凝胶的响应速率成为了智能水凝胶研究领域的重要课题之一。本文主要综述了具有快速响应特性的环境响应智能水凝胶的构建策略与方法,重点介绍了3类具有不同结构的快速响应型智能水凝胶,即具有多孔结构的快速响应智能水凝胶、具有梳状结构的快速响应智能水凝胶以及具有微球复合结构的快速响应智能水凝胶。     

刺激响应性短肽水凝胶研究进展

随着现代化工技术的不断进步,刺激响应性水凝胶越来越受到科研人员的关注.刺激响应性短肽水凝胶可在外界的刺激包括pH值、温度、光和酶等物理和化学因素下做出相应的表现,控制其化学构象或理化性质的改变,对所受到的刺激做出相应的响应.对其独特性质进一步研究,将其运用于生物传感、药物控释和组织修复等医学领域,有着较好的发展前景.本...     

刺激-响应型水溶性聚合物的研究进展

对刺激响应型水溶性聚合物近年来的发展进行了综述。介绍了能够对 p H、温度、光、电解质、电场、分子、剪切等外界刺激做出响应的水溶性聚合物 /凝胶的结构特点、响应机理和研究现状     

热和光刺激响应型离子凝胶研究进展

热和光刺激响应型离子凝胶是能够在温度和光的刺激下,离子凝胶的体积能够发生突变的一类凝胶。这一类离子凝胶在致动器和智能开关等领域具有潜在的应用前景。综述了热和光刺激响应型离子凝胶的分类,并对其发展趋势进行了展望。     

刺激响应型超分子凝胶的研究进展

近年来,超分子材料[1]的研究一直是科学研究界的热点话题之一,随着研究的深入,刺激响应型超分子凝胶[2]作为新型的智能超分子材料备受研究者的关注。超分子凝胶由于其具有三维网状结构,通过非共价键相互作用进行的小分子自组装,从而合成易于回收、符合绿色化学要求的新型智能材料。本文主要阐述了超分子凝胶在受到外界刺激情况下所引发的多种响应体系,说明它在医药、软材料制备[3]、识别传感器[4]以及催化[5]等领域的重要意义,并对刺激响应型超分子凝胶的未来发展进行展望。     

影响电刺激响应型智能水凝胶弯曲行为的因素

电刺激响应型水凝胶是一类在电场作用下可以发生溶胀、收缩、变形、弯曲等行为的智能型凝胶,其中弯曲行为具有良好的应用前景。本文主要对智能型水凝胶发生弯曲行为的机理、影响因素以及在药物输送系统中的应用进行了综述并进行展望。     

智能聚合物凝胶的研究进展

智能聚合物凝胶是一种包含大量溶剂但又不溶解的高分子或大分子聚集体,它们具有良好的溶胀性能和三维空间网络结构,又被称为"软材料",具有独特的物理化学性质。广泛应用于药物载体、生物传感、形状记忆材料等领域。本文综述近年来国内外开发的智能响应性凝胶,重点介绍响应性凝胶的结构特征和性能特点。并对响应性聚合物凝胶的发展进行展望。     

智能水凝胶研究进展

作为一种智能高分子材料,智能水凝胶具有良好的应用前景,本文重点介绍了刺激响应型智能水凝胶、高强智能水凝胶及自愈合智能水凝胶的结构特征、性能特点及研究现状,并对智能水凝胶的未来发展进行了展望。     

双多重刺激响应水凝胶应用于伤口愈合的研究进展

介绍了伤口愈合的过程以及愈合过程中伤口处微环境的变化,叙述了目前根据伤口处不同环境变化(如pH、温度、活性氧含量和葡萄糖含量等)而设计的智能响应水凝胶,总结了可以应对2种及以上伤口微环境变化的双重或多重刺激响应性水凝胶的制备过程,以及水凝胶如何对伤口实现智能响应和精准治疗的应用,并讨论了今后应用于伤口愈合水凝胶的设计方向。认为目前的水凝胶多数用于浅表创伤的治疗,如何对深度损伤的慢性伤口实现加速愈合的效果是扩展水凝胶应用的关键;从材料角度出发,可以深度研究创面愈合机制,设计开发多重刺激响应水凝胶以满足不同类型的创面的需求,从而使水凝胶在伤口愈合方面有更广阔的应用前景。     

刺激响应型药物释放体系的研究进展

刺激响应型聚合物在药物释放领域的应用越来越广泛,研究也越来越受到重视.根据不同类型的刺激条件,综述了pH响应型、温度响应型、葡萄糖响应型、场响应型等一系列刺激响应型药物释放体系的应用和研究进展.     

Thermoresponsive nanocomposite hydrogels with high mechanical strength and toughness based on a dual crosslinking strategy

The practical application of thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) hydrogels are severely limited by their poor mechanical properties. Herein, we reported a series of dual crosslinked (DC) PNIPAM hydrogels with superior mechanical properties prepared by simple copolymerization of N-isopropylacrylamide and sodium acrylate (SA) in the laponite RDS suspension, following by a soaking process in multivalent metal cations (e.g., Ca²⁺, Al³⁺, Fe³⁺) aqueous solutions to form ionic coordination interactions with  COO groups of copolymer side chains. The effect of laponite RDS, AANa (sodium acrylate), and metal cation (e.g., Fe³⁺) concentrations on the mechanical properties and deswelling properties of the DC hydrogels are evaluated. The DC hydrogel prepared with 10 w/v% laponite RDS, 0.25 mol/L AANa and 0.45 mol/L Fe³⁺ possesses the best mechanical properties (ca. 1.1 MPa of tensile strength, 9.1 MPa of compression strength at 80% of compression strain, 1.4 MPa of elastic modulus and 1.3 MJ/m³ of toughness). Moreover, we also discovered that the DC hydrogels crosslinked by Fe³⁺ showed better mechanical properties due to the larger charge and ion radius of Fe³⁺.     

Enhancing mechanical strength of hydrogels via IPN structure

In this investigation, polyacrylamide (PAAm) as the flexible network is introduced to enhance the mechanical strength of hyaluronic acid–gelatin (HA–Gel) hydrogels by interpenetrating polymer network (IPN). The structure, mechanical property, and rheology property of the IPN hydrogels are investigated. It is found that the compressive strength of the HA–Gel/PAAm IPN hydrogels has increased five times higher than that of HA–Gel hydrogels. Rheological test demonstrates that elastic moduli (G′) and viscous moduli (G″) of HA–Gel/PAAm IPN hydrogels increase 100 times higher than those of HA–Gel hydrogels. Moreover, the HA–Gel hydrogels are fractured under the low compressive stress, whereas HA–Gel/PAAm IPN hydrogels are not broken under the high compressive stress. It is envisioned that the IPN hydrogels will be an effective approach to enhance the mechanical strength and broaden the range of hydrogels' applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44503.     

Reinforcing biopolymer hydrogels with ionic‐covalent entanglement hydrogel microspheres

Microscopic hydrogel spheres can be used to improve the mechanical properties of conventional hydrogels. We prepared ionic‐covalent entanglement (ICE) hydrogel microspheres of calcium cross‐linked gellan gum and genipin cross‐linked gelatin using a water‐in‐oil emulsion‐based processing technique. The method was optimized to produce microspheres with number average diameter 4 ± 1 µm. These ICE microspheres were used to reinforce gelatin hydrogels and improve their compressive mechanical properties. The strongest microsphere reinforced hydrogels possessed a compressive mechanical stress at failure of 0.50 ± 0.1 MPa and a compressive secant modulus of 0.18 ± 0.02 MPa. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40557.     

Effects of oxidant and dopants on the properties of cellulose/PPy conductive composite hydrogels

Cellulose/Polypyrrole (PPy) composite hydrogels were prepared by in situ chemically oxidative polymerization of pyrrole in the cellulose matrix. Ferric chloride (FeCl₃) was used as an oxidant and four sulfonic compounds were used as dopants in order to investigate the effects on the properties of cellulose/PPy conductive composite hydrogels. The extent of polymerization of PPy was determined by the amount of the oxidant and the composite hydrogels with oxidant at 0.3M?0.5M exhibited the higher conductivities for the intrachain and interchain conductivities of conductive polymers; the fracture stress of the composite hydrogels could be up to 26.25 MPa with a strain of 86.8% when the oxidant was at 0.5M. Doping is an efficient way to improve the conductivity of the composite hydrogels and four kinds of dopant were compared in this work. Long alkane chain and side group in dopants can increase the steric hindrance of PPy polymerization which resulted in the lower conductivity of the composite hydrogels compared to dopants with smaller steric hindrance. The conductivity of the composite hydrogel firstly increased and then decreased with the concentration of dopants from 0.1M to 1.0M in this work. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43759.     

ATRP法制备环境响应型智能膜材料的研究进展

聚（N-异丙基丙烯酰胺）（PNIPAM）作为一种常见的智能材料,同时具有温度响应特性和乙醇浓度响应特性。本文以PNIPAM聚合物为主线,着重介绍了利用原子转移自由基聚合（ATRP）法制备温度响应型、温度及pH值双重响应型、乙醇浓度响应型智能膜材料的研究成果。其中,温度响应型智能膜主要介绍PNIPAM均聚物接枝膜;温度及pH值双重响应型智能膜主要介绍PNIPAM与pH值响应型聚合物的嵌段接枝膜;乙醇浓度响应型智能膜主要介绍PNIPAM无规共聚物接枝膜。另外,还介绍了其它响应型智能膜,包括手性分子及离子响应型接枝膜的研究成果。基于ATRP法在文中所述的优点以及在膜改性研究方面的广泛应用,相信该方法在制备环境响应型智能膜材料以及推动智能膜实际工业应用方面将扮演重要角色。     

Mechanical properties of interpenetrating polymer network hydrogels based on hybrid ionically and covalently crosslinked networks

Hydrogels are polymer networks swollen in water. Because of their soft and wet nature, and their ability to show large volume changes, hydrogels can be useful in many biomedical and actuator applications. In these applications, it is crucial to tune the mechanical and physical properties of a hydrogel in a controllable manner. Here, interpenetrating polymer networks (IPNs) made of a covalently crosslinked network and an ionically crosslinked network were produced to investigate the effective parameters that control the physical and mechanical properties of an IPN hydrogel. Covalently crosslinked polyacrylamide (PAAm) or poly(acrylic acid) (PAA) networks were produced in the presence of alginate (Alg) that was then ionically crosslinked to produce the IPN hydrogels. The effect of ionic crosslinking, degree of covalent crosslinking, AAm : Alg and AA : Alg ratio on the swelling ratio, tensile properties, indentation modulus, and fracture energy of IPN hydrogels was studied. A hollow cylindrical hydrogel with gradient mechanical properties along its length was developed based on the obtained results. The middle section of this hydrogel was designed as a pH triggered artificial muscle, while each end was formulated to be harder, tougher, and insensitive to pH so as to function as a tendon‐like material securing the gel muscle to its mechanical supports. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2504–2513, 2013     

Synthesis and drug‐release studies of low‐fouling zwitterionic hydrogels with enhanced mechanical strength

Reversible addition–fragmentation chain‐transfer polymerization was introduced to prepare a series of zwitterionic poly(hydroxyethyl methacrylate)‐g‐poly(sulfobetaine methacrylate) (PSBMA) hydrogels (HSGs) with different monomer feed ratios. Compared with PSBMA hydrogels, these hydrogels exhibited enhanced mechanical strengths. Then, the HSGs were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and swelling measurements. We found that the equilibrium swelling ratios, mechanical strengths, and drug‐release behaviors were significantly affected by the feed ratios of the gels. The hydrophilic tetracycline hydrochloride release results suggest that the hydrophilic drug release from the HSGs could be prolonged by the variation of the hydroxyethyl methacrylate amount in the gel networks. The bovine serum albumin adsorption data showed that the zwitterionic HSG with 18.2 wt % sulfobetaine methacrylate exhibited good protein‐resistance properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41041.     

Effect of the sodium dodecyl sulfate/monomer ratio on the network structure of hydrophobic association hydrogels with adjustable mechanical properties

The study of gel‐network structure is not as extensive as the study of the application of hydrogels. However, the distribution of the inner structure is crucial for designing hydrogels with tunable mechanical properties to meet certain kinds of demands. In this study, a series of hydrophobic association hydrogels (HA‐gels) were synthesized by free‐radical micellar copolymerization in a sodium dodecyl sulfate (SDS) surfactant solution. The hydrophobic monomer was palmityl alcohol poly(oxyethylene acrylate) (AEO–AC), which is an ecofriendly alternative to the traditional octyl phenol poly(oxyethylene acrylate). Interestingly, we found that the molar ratio [or ratio point (R)] of SDS to AEO–AC played a key role in tuning the mechanical properties. All series HA‐gels denominated a similar down–up–down tendency with increasing R, and the best R is 3. This result was consistent with the microscopic network structure number of the hydrophobic monomer (N_H = 21–24), and this indicated that each hydrophobic monomer associated three SDS monomers in its internal networks. The resulting AEO–AC–acrylamide gels exhibited the best mechanical strength (yield maximum broken stress = 218 kPa) and the maximum effective crosslink density. Moreover, the relationship between the network structure and the mechanical properties of the HA‐gels was investigated with various Rs. Two different interaction effects of distribution between SDS and AEO–AC are discussed in detail. The HA‐gels exhibited self‐healing properties and maintained their shape in water over 160 days. The results indicate that changing R is an effective method for tuning the mechanical properties of HA‐gels as a type of prospective biomedical material. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45196.     

Engineering hydrophobically associated hydrogels with rapid self-recovery and tunable mechanical properties using metal-ligand interactions

In this contribution, hydrophobic association and metal-ligand coordination have been employed in a dual physical crosslinking strategy to access hydrogels based on micellar copolymerization of acrylamide and a hydrophobic acrylic monomer (containing terpyridine (terpy) for metal-ligand interaction). The mechanical properties of these hydrogels are strongly influenced by the thermodynamic stability and kinetic lability of the metal-terpy crosslinks present in these materials. While the hydrogel tensile strength and stability on water exposure are enhanced by choosing stronger Fe²⁺-terpy crosslinks, the weaker and more kinetically labile Zn²⁺-terpy coordination bonds enable significantly higher energy dissipation under tensile loading and self-healing in the resultant hydrogels.