水溶性丙烯酸聚合物的改性及其应用

叙述了水溶性丙烯酸聚合物的改性及其在涂料、胶粘剂、敏感性水凝胶、皮革涂饰剂等方面的应用新进展。     

表面活性剂胶束实现疏水分子在聚合物微凝胶层层组装膜中的高效负载

基于层层组装技术制备了聚烯丙基胺-葡聚糖微凝胶(记作PAH-D)/透明质酸钠(HA)膜, 将包覆有芘分子的十二烷基硫酸钠(SDS)表面活性剂胶束基于静电作用力负载到PAH-D/HA微凝胶膜中, 实现了疏水分子芘在微凝胶膜中的高效负载. 紫外-可见吸收光谱和荧光光谱证实了SDS胶束包覆的芘分子被稳定地负载在PAH-D微凝胶膜中. 透过光谱表明负载有芘分子的(PAH-D/HA)*10微凝胶膜在可见光区仍保持良好光学透过性. 芘在膜中的负载量可以通过改变PAH-D/HA微凝胶膜的沉积周期数和SDS胶束中包覆芘分子的浓度而实现调控. 具有光致变色性质的螺吡喃分子同样可以借助SDS胶束负载到PAH-D/HA微凝胶膜中, 制备具有光致变色性质的层层组装膜. 本工作为疏水有机分子在层层组装聚合物膜中的高效负载提供了一种简便、易行的方法.     

超分子聚合物凝胶

作为非常重要的软物质材料,超分子聚合物凝胶代表了一个全新的概念和更复杂的凝胶体系.这种新型的超分子体系的构建,是基于多种非共价相互作用协同的多层次组装.即小分子构筑基元首先组装成为超分子聚合物,而这些非共价聚合物的多层次组装形成凝胶的纳米结构.超分子聚合物凝胶无论是在结构上,还是在性能上都具有很多崭新的特点.因此,尽管有关超分子聚合物凝胶的研究开展的时间还很短,这一体系所表现出的独特性以及巨大潜力已经引起科学家们越来越广泛的关注.本文简要综述了这一领域的最新进展.主要论述基于多种非共价相互作用的超分子聚合物凝胶的构建以及对其力学性能的调控.     

锂离子电池凝胶聚合物电解质的研究进展

由于凝胶聚合物电解质具有较好的机械加工性能和安全性能以及较高的室温离子电导率,因而得到广泛的研究与应用。综述了聚偏氟乙烯、聚丙烯腈、聚甲基丙烯酸甲酯和聚氧化乙烯等锂离子电池凝胶聚合物电解质近几年的研究进展,主要介绍了这些凝胶聚合物电解质体系性能的优缺点以及对其改性研究的各种探索。特别是对目前研究最广泛的聚偏氟乙烯体系的改性进行了较为详细的论述。其中,添加无机纳米粒子的改性是目前的研究热点,是凝胶聚合物电解质的发展趋势,并对凝胶聚合物电解质的未来发展作了展望。     

有机锡聚合物的合成及应用

介绍了有机锡聚合物的研究现状。重点介绍了有机锡聚合物的各种合成方法及其在海洋防污涂料、木材防腐保护、荧光染料和聚合物改性等方面的应用。     

锂离子电池凝胶聚合物电解质改性的研究现状

从目前凝胶聚合物电解质的研究现状及问题出发,重点介绍了两种改性凝胶聚合物电解质的方法。无机纳米粒子复合凝胶聚合物电解质能够降低结晶型聚合物的结晶度,提高其离子电导率,改善其力学性能和稳定性;多孔凝胶聚合物电解质能够实现在较宽的温度范围内能保持较高的离子电导率和较好的机械强度及尺寸稳定性。最后,对凝胶聚合物电解质的改性研究方向作出了展望。     

氢键结合超分子水凝胶的形成与结构调控

近年来,依靠单体单元间可逆和高度取向的非共价作用力形成超分子聚合物(supramolecularpolymer)得到广泛关注[1,2].在溶液中,超分子单体单元之间通过非共价键相互作用,形成三维网络结构并将有机溶剂或水包裹形成超分子凝胶[3,4].相对于聚合物凝胶,超分子凝胶具有以下优点.(1)生     

溶胶-凝胶法制备的罗丹明B/二氧化钛分子印迹聚合物的结构与吸附性能

以罗丹明B为模板分子,以钛酸丁酯为交联剂,采用溶胶-凝胶法在酸性条件下制备了罗丹明B二氧化钛溶胶-凝胶分子印迹聚合物;利用傅立叶变换红外光谱和透射电镜分析了分子印迹聚合物的结构,使用热重分析测定了其热稳定性,采用静态吸附和动态吸附方法考察了其吸附性能,并与非印迹聚合物进行了对比.结果表明,与非印迹聚合物相比,印迹聚合物具有网络状多孔隙凝胶微结构及对模板分子的特异性识别结合位点,因而对模板分子具有更好的吸附性能和特异选择性.其原因可能在于,模板分子上的羰基与钛酸丁酯水解产生的羟基产生氢键作用,使钛酸围绕于模板分子周围,并通过缩聚形成凝胶;当模板分子洗脱后,孔隙得到保留并形成网络状凝胶,从而能够吸附更多的模板分子.     

用红外光谱研究具有互穿网络结构的pH/温度双重敏感性微凝胶的相转变行为

采用傅立叶变换红外光谱仪测试了由聚(N-异丙基丙烯酰胺)(PNIPA)和聚丙烯酸(PAA)两种聚合物网络形成的具有互穿聚合物网络结构(IPN)的pH/温度双重敏感性微凝胶D2O分散液,通过差谱技术对不同pH值和温度条件下的红外吸收光谱进行处理,研究微凝胶相转变过程中分子链微环境的变化.结果表明,随着D2O介质的pH值增...     

海藻酸钠的疏水改性及释药性能研究

为了提高对疏水性药物的负载量和缓释作用,将海藻酸钠氧化后与十二胺反应使其进行疏水改性.对改性后聚合物结构进行了表征.研究了聚合物在水溶液及盐溶液中的粘度变化;将聚合物分散于NaCl/CaCl2的混合溶液中制备成凝胶微球,对药物布洛芬进行了包埋释放实验.结果表明,疏水改性后的海藻酸钠粘度增加,其凝胶微球对布洛芬负载量提高,具有较好的缓释作用.     

高分子微凝胶控制合成无机-有机复合材料研究进展

高分子微凝胶是一类具有三维网络结构的分子内交联的高分子球形微粒,其物理、化学性质与其构象变化有着密切的关系,对于外界环境条件如温度、pH、离子强度、电场或磁场等的改变,微凝胶即表现出相应的体积相转变特性.近年来,基于高分子微凝胶对外界的刺激相应性与无机纳米粒子的特殊性能制备得到了各种有机-无机复合材料.本文根据微凝胶在无机微、纳米材料制备过程中所起的作用,将基于高分子微凝胶制备无机-有机复合微、纳米材料的方法分为原位合成法、物理诱捕法和聚合法,并分别从各类方法的特点和应用等方面进行详尽地分析和阐述.     

Aqueous microgels for the growth of hydroxyapatite nanocrystals

In present article, we demonstrate that aqueous microgels can be used as containers for the in-situ synthesis of hydroxyapatite. The hydroxyapatite nanocrystals (HAp NCs) become integrated into microgels forming hybrid colloids. The HAp NCs loaded in the microgel can be varied over a broad range. The HAp NCs are localized within the microgel corona. The deposition of the inorganic nanocrystals decreases the colloidal stability of the microgels and leads to particle aggregation at high HAp NCs loading. Because of the strong interactions between HAp NCs and polymer chains, the swelling degree of microgels decreases, and temperature-sensitive properties disappear at high loading of the inorganic component. We demonstrate that hybrid colloids can be used as building blocks for the preparation of nanostructured films on solid substrates.     

Tunable polymer microgel particles and their study using microscopy and real-time deformability cytometry

We report the preparation and mechanical properties of highly swellable, spherical polymer microgels synthesized by precipitation copolymerization of divinylbenzene-55 (DVB), 4-methylstyrene (4MS), and maleic anhydride (MA) at different cross-linker contents, in a range of methylethylketone (MEK) and heptane solvent mixtures. Microgels were characterized by optical and confocal microscopy, and their mechanical properties tested using real-time deformability cytometry (RT-DC), a technique developed to analyze cell properties by measuring deformation under shear stress. Hydrolysis of anhydride groups gave microgels with diameters ranging from 10 to 22 μm when swollen in saline, depending on vol% MEK and cross-linker loading. Young's moduli of the microgels could be tuned from 0.8 to 10 kPa by adjusting cross-linker content and MEK/heptane solvent composition, showing an inverse relationship between the effects of vol% MEK and %DVB on microgel properties. These microgels also show strain-stiffening in response to increasing shear stresses. Extension of the RT-DC method to the study of polymer colloids thus enables high-throughput analysis of microgels with tunable mechanical characteristics.     

Varying the Stiffness and Diffusivity of Rod-Shaped Microgels Independently through Their Molecular Building Blocks

Microgels are water-swollen, crosslinked polymers that are widely used as colloidal building blocks in scaffold materials for tissue engineering and regenerative medicine. Microgels can be controlled in their stiffness, degree of swelling, and mesh size depending on their polymer architecture, crosslink density, and fabrication method—all of which influence their function and interaction with the environment. Currently, there is a lack of understanding of how the polymer composition influences the internal structure of soft microgels and how this morphology affects specific biomedical applications. In this report, we systematically vary the architecture and molar mass of polyethylene glycol-acrylate (PEG-Ac) precursors, as well as their concentration and combination, to gain insight in the different parameters that affect the internal structure of rod-shaped microgels. We characterize the mechanical properties and diffusivity, as well as the conversion of acrylate groups during photopolymerization, in both bulk hydrogels and microgels produced from the PEG-Ac precursors. Furthermore, we investigate cell-microgel interaction, and we observe improved cell spreading on microgels with more accessible RGD peptide and with a stiffness in a range of 20 kPa to 50 kPa lead to better cell growth.     

pH-Sensitive microgels functionalized with folic acid

One of the most promising strategies in anticancer therapies is the targeted delivery through malignancy-associated cellular markers. The design of new synthetic devices with enhanced stimuli-responsive sensitivity and targeting ligands is a promising field for the development of cancer-specific delivery systems. One of the pathways to achieve this aim is the chemical functionalization of nanodevices such as microgels. The p-nitrophenyl acrylate (NPA) is an active ester molecule with a group that can be easily cleavaged by the nucleophilic attack of species such as amines. This modification consists of an easy chemical reaction that leads to several types of functionalized microgels, which are originally made up of NPA as one of their constituent monomers.

Here is reported the chemical functionalization of NPA-based microgels by incorporating pH-sensitive functional groups and folic acid as a tumor targeting ligand into the same initial polymer network. For this purpose, microgels of p-nitrophenyl acrylate (NPA)-co-methacrylamide (MeAM) synthesized by precipitation polymerization, were modified with two different pyridine derivatives: 2-aminomethylpyridine (2-AMP) and 2-aminopyridine (2-AP), thus pH-sensitive microgels with acid pH swelling capacity were obtained. The equilibrium swelling behaviour was studied as a function of pH, ionic strength, copolymer composition and type of pyridine derivative. In addition, the microgels were derivatized with ethylene diamine, to obtain amino-functionalized microgels to which the folic acid was subsequently attached as the targeting ligand. As final step, pH-sensitive groups and folic acid were equimolarly attached to the polymer chains to obtain the fully functionalized microgels.     

Effect of chemical composition on properties of pH-responsive poly(acrylamide-co-acrylic acid) microgels prepared by inverse microemulsion polymerization

In this research, a series of pH-responsive microgels based on acrylamide (AM), acrylic acid (AA) as the main monomers, and N,N′-methylenebisacrylamide as a divinyl cross-linking agent, have been prepared by inverse microemulsion polymerization. The effect of chemical composition of poly(acrylamide-co-acrylic acid) (P(AM-co-AA)) on hydrodynamic diameters, morphology, swelling ratios and pH-responsive behaviour and thermal properties of microgels were discussed. With an increase of the mole percentages of AA in the feed ratio, the microgels have higher swelling ratios. The TEM photographs show that the spherical morphology of the microgels are regular relatively. Comparing with PAM microgels, number-average diameters of P(AM-co-AA) microgels were larger because of the presence of AA chain segment in the polymer chain. Turbidities of microgels determined through UV–vis spectrophotometer indicate that the microgels exhibit favourable pH-responsive behaviour, and responsive pH value is related to the dissociation constant of AA. Moreover, thermal stable properties of microgels were confirmed by differential scanning calorimeter. It was observed that an increase in the mole percentages of AA in the feed ratio provided lower glass transition temperature and thermal decomposition temperature of pH-responsive microgels.     

New “smart” poly(NIPAM) microgels and nanoparticle microgel hybrids: Properties and advances in characterisation

This review is devoted to poly(NIPAM) based microgels and nanoparticle/polymer hybrid microgels. It tries to give a brief overview of recent developments with respect to new systems and experimental methods. The properties of these fascinating materials are reported together with advances in their characterisation by imaging and scattering techniques. Aspects of their application in the area of mesotechnology will also be discussed.     

Polymer microgels: reactors for semiconductor, metal, and magnetic nanoparticles

We report a strategy for the production of materials with structural hierarchy. The approach employs polymer microgels as templates for the synthesis of semiconductor, metal, or magnetic nanoparticles (NPs). We show that NPs with predetermined dimensions and size-dependent properties can be synthesized by using a very delicate balance between the reaction conditions, the composition and the structure of microgel templates, and the concentration of NPs in the microgel. Postheat treatment of microgels doped with semiconductor nanoparticles reduces NP polydispersity and allows control of their photoluminescence. Microgel templates are particularly beneficial in the synthesis of polymer microspheres heavily loaded with monodisperse superparamagnetic Fe(3)O(4) NPs. Hybrid submicrometer-size microgels have promising potential applications in photonics, catalysis, and separation technologies.     

Structural properties of thermoresponsive poly(N-isopropylacrylamide)-poly(ethyleneglycol) microgels

We present investigations of the structural properties of thermoresponsive poly(N-isopropylacrylamide) (PNiPAM) microgels dispersed in an aqueous solvent. In this particular work poly(ethyleneglycol) (PEG) units flanked with acrylate groups are employed as cross-linkers, providing an architecture designed to resist protein fouling. Dynamic light scattering (DLS), static light scattering (SLS), and small angle neutron scattering (SANS) are employed to study the microgels as a function of temperature over the range 10 °C ≤ T ≤ 40 °C. DLS and SLS measurements are simultaneously performed and, respectively, allow determination of the particle hydrodynamic radius, R(h), and radius of gyration, R(g), at each temperature. The thermal variation of these magnitudes reveals the microgel deswelling at the PNiPAM lower critical solution temperature (LCST). However, the hydrodynamic radius displays a second transition to larger radii at temperatures T ≤ 20 °C. This feature is atypical in standard PNiPAM microgels and suggests a structural reconfiguration within the polymer network at those temperatures. To better understand this behavior we perform neutron scattering measurements at different temperatures. In striking contrast to the scattering profile of soft sphere microgels, the SANS profiles for T ≤ LCST of our PNiPAM-PEG suspensions indicate that the particles exhibit structural properties characteristic of star polymer configurations. The star polymer radius of gyration and correlation length gradually decrease with increasing temperature despite maintenance of the star polymer configuration. At temperatures above the LCST, the scattered SANS intensity is typical of soft sphere systems.     

Electrochemical impedance spectroscopy fingerprints the ion selectivity of microgel functionalized ion-exchange membranes

Surface modification methods are applied to alter interfacial phenomena and improve ion transport through membranes. In this work we present a novel method for tailoring the surface of cation-exchange membranes based on the deposition of thin microgel monolayers. The charge of such layers exerts a strong influence on the monovalent-ion-selectivity, and this is reflected in the electrochemical impedance responses. Membranes coated with uncharged microgels show similar behavior to that of unmodified ones, with impedance spectra dominated by low-frequency diffusional arcs. However, membranes modified with positively charged microgels exhibit an increased resistance due to the hindered transport of cations through the modification. An additional high-frequency capacitive arc is obtained with the monovalent-ion-selective membranes, which is attributed to concentration polarization effects at the membrane/modification interface. The characteristic frequency of this arc decreases with the valency of the ion, thus proving that multivalent ions pass through the modification layer at rates much slower than monovalent ones. Accordingly, electrochemical impedance spectroscopy has been used to feature monovalent-ion-selective properties of layered membranes.