聚N-异丙基丙烯酰胺类凝胶及其温敏性和酸敏性的研究

以N-异丙基丙烯酰胺为基础制成四种凝胶:①N-异丙基丙烯酰胺均聚凝胶;②N-异丙基丙烯酰胺与甲基丙烯酰胺共聚凝胶;③N-异丙基丙烯酰胺与甲基丙烯酸钠共聚凝胶;④N-异丙基丙烯酰胺与丙烯酰胺共聚,经水解生成的凝胶。探讨了引发剂、促进剂和交联剂及单体总浓度对凝胶化时间或凝胶的溶胀性能的影响,以及凝胶的温敏与酸敏相变条件。设计了温敏凝胶萃取过程,并对牛血清蛋白、碱性蛋白酶以及某种人体激素溶液进行浓缩实验。结果表明其具有良好的实用前景。     

聚(N-异丙基丙烯酰胺-共聚-烯丙基硫脲)智能微凝胶的制备及其Hg2+响应性能的研究

以N-异丙基丙烯酰胺(NIPAM)和烯丙基硫脲(ATU)为共聚单体,N,N’-亚甲基双丙烯酰胺(MBA)为交联剂,2,2′-偶氮二(2-甲基丙基咪)二盐酸盐(V50)为引发剂,通过沉淀聚合法制备了一种可用于Hg²⁺检测与去除的聚(N-异丙基丙烯酰胺-共聚-烯丙基硫脲)(PNA)智能微凝胶。利用傅里叶变换红外光谱仪(FT-IR)、X射线光电子能谱仪(XPS)和扫描电镜(SEM)对微凝胶进行了化学成分和形貌表征。利用动态光散射纳米粒度分析仪(DLS)对微凝胶的粒径分布及温度响应性进行了研究。探究了干扰离子、pH和温度对微凝胶Hg²⁺响应性能的影响。利用原子吸收光谱仪(AAS)探究了PNA微凝胶对Hg²⁺的吸附去除效果。结果显示,PNA微凝胶具有良好的温敏性以及对Hg²⁺的特异响应性,响应Hg²⁺后引起的收缩比(RD)随着ATU单体比例的增加而减小,并确定了最佳检测温度为30℃。随着Hg²⁺浓度的增加,RD值逐渐减小,根据Hg²⁺浓度与RD...     

N-异丙基丙烯酰胺高分子水凝胶研究进展

N-异丙基丙烯酰胺基高分子水凝胶的研究进展做了综述。简要介绍了该类水凝胶的合成方法,重点分析了不同共聚单体及交联剂对水凝胶溶胀性能和环境响应性的影响,尤其是快速响应水凝胶的合成方法和N-异丙基丙烯酰胺/天然大分子水凝胶的特点。本文也简单介绍了该类水凝胶在不同领域内的应用。     

聚甜菜碱型疏水聚合物的合成及性能评价

以苯甲酰氯、丙烯酸、N,N-二甲基-1,3-丙二胺和氯乙酸为主要原料,合成了一种甜菜碱型功能单体丙烯酰胺丙基甜菜碱。丙烯酰胺丙基甜菜碱单体、丙烯酰胺、疏水单体进行三元共聚,得到聚甜菜碱型疏水聚合物,对聚合物溶液的抗盐性能进行了评价。结果表明,新型聚甜菜碱型疏水聚合物溶液具有优良的盐增稠性能。     

水溶性疏水缔合聚合物单体的合成

水溶性疏水缔合聚合物含有大量的亲水基团和少量的疏水基团,疏水基团间的疏水缔合作用使这种聚合物具有独特的增粘、抗剪切、耐温和耐盐的溶液性能,通常采用亲水单体和疏水单体共聚制备这类聚合物。对常用亲水单体AMPS及各类疏水单体如季铵盐不饱和单体AMPDAC和DAMAB、长链丙烯酸酯,N-烷基丙烯酰胺和N-芳烷基丙烯酰胺的合成进行了综述。     

两亲性聚异丙基丙烯酰胺的合成及其温敏性研究

通过自由基聚合和端酰胺键合的方法合成了一系列分子量不同的端胺基聚 N-异丙基丙烯酰胺 ( PNIPAm)及其含双十二和十四长链疏水烷基两亲性聚合物 ,通过聚合物水溶液的透光率随温度变化曲线的拐点确定其低临界溶解温度 ( LCST) ,并研究其影响因素。结果表明 ,两亲性 PNIPAm水溶液相转变温度不仅受聚合物结构如亲、疏水链长比的影响 ,而且与溶液浓度的也有较大关系。     

N-异丙基丙烯酰胺功能性共聚物的结构及特性研究进展

N-异丙基丙烯酰胺共聚物是一种新型的智能材料,可用于制备药物控释材料、酶的固定材料、脱水剂等。概述了N-异丙基丙烯酰胺共聚物及其各类共聚单体的大分子结构、氢键效应及刺激响应性等特性。     

DEA接枝共聚物的制备及其温度响应行为

为改善合成聚合物聚N,N-二乙基丙烯酰胺(PDEA)的生物相容、生物降解性,在引发剂K2S2O8的作用下,将主单体N,N-二乙基丙烯酰胺(DEA)和改性单体丙烯酸(AA)接枝聚合到天然高分子羧甲基壳聚糖(CMCS)骨架上,考察反应条件对接枝共聚物接枝率、接枝效率和温度响应行为的影响。红外光谱仪表征共聚物结构,紫外/可见分光光度计检测不同条件下聚合物溶液的透光率。结果表明,当单体AA与DEA质量比为1∶50、单体总用量为1.5 g时,共聚物具有显著的温度响应行为,且相转变温度较高为31℃。     

新型P(NIPAAm-co-IA)pH敏感智能水凝胶的合成与性能研究

采用溶液共聚法合成了聚(N-异丙基丙烯酰胺-co-衣康酸)(P(NIPAAm-co-IA))pH敏感性阴离子型水凝胶.通过正交设计实验研究了共聚单体比值、单体浓度、交联剂用量、引发剂用量等因素对凝胶性能的影响,分析了各因素的影响程度和最优工艺条件,结果显示,在所考察的范围内,最优工艺条件为:n(IA):n(NIPAAm...     

pH敏感P(MAA-co-BMA)水凝胶的溶胀行为

以甲基丙烯酸(MAA)和甲基丙烯酸丁酯(BMA)为共聚单体、N,N-亚甲基双丙烯酰胺为交联剂、偶氮二异丁腈为引发剂,用溶液聚合法合成P(MAA-co-BMA)水凝胶,研究其吸水溶胀性和pH敏感性。结果表明,BMA投料为摩尔分数5%的共聚水凝胶在211℃以下处于高弹态,其吸水溶胀比可达52;该凝胶烘干和冻干处理后的pH敏感性都很好,即平衡溶胀比随着pH增大而增大;而冻干凝胶因具有规律的大孔结构,在不同pH溶液中的平衡溶胀比差异更大。     

Synthesis of poly(trioctylammonium p-styrenesulfonate) homopolymers and block copolymers by RAFT polymerization

A method to prepare sulfonated polystyrene-containing block copolymers has been investigated by neutralizing styrene sulfonic acid with trioctylamine to produce the hydrophobic monomer trioctylammonium p-styrenesulfonate (SS-TOA). This monomer was polymerized by reversible addition fragmentation chain transfer (RAFT) polymerization to produce PSS-TOA homopolymers. A PSS-TOA homopolymer was then used as a macro-RAFT agent for the polymerization of styrene to prepare poly(trioctylammonium p-styrenesulfonate)-block-poly(styrene) (PSS-TOA-b-PS). These block copolymers could be ion-exchanged to produce either the hydrophilic sodium salt form of PSS or a hydrophobic quaternary ammonium salt. This approach will be useful for preparing PSS-containing block copolymers with a range of hydrophobic blocks for applications such as ion-exchange membranes.     

Vesicular and micellar self‐assembly of stimuli‐responsive poly(N‐isopropyl acrylamide‐b‐9‐anthracene methyl methacrylate) amphiphilic diblock copolymers

Dually responsive amphiphilic diblock copolymers consisting of hydrophilic poly(N‐isopropyl acrylamide) [poly(NIPAAm)] and hydrophobic poly(9‐anthracene methyl methacrylate) were synthesized by reversible addition fragmentation chain‐transfer (RAFT) polymerization with 3‐(benzyl sulfanyl thiocarbonyl sulfanyl) propionic acid as a chain‐transfer agent. In the first step, the poly(NIPAAm) chain was grown to make a macro‐RAFT agent, and in the second step, the chain was extended by hydrophobic 9‐anthryl methyl methacrylate to yield amphiphilic poly(N‐isopropyl acrylamide‐b‐9‐anthracene methyl methacrylate) block copolymers. The formation of copolymers with three different hydrophobic block lengths and a fixed hydrophilic block was confirmed from their molecular weights. The self‐assembly of these copolymers was studied through the determination of the lower critical solution temperature and critical micelle concentration of the copolymers in aqueous solution. The self‐assembled block copolymers displayed vesicular morphology in the case of the small hydrophobic chain, but the morphology gradually turned into a micellar type when the hydrophobic chain length was increased. The variations in the length and chemical composition of the blocks allowed the tuning of the block copolymer responsiveness toward both the pH and temperature. The resulting self‐assembled structures underwent thermally induced and pH‐induced morphological transitions from vesicles to micelles and vice versa in aqueous solution. These dually responsive amphiphilic diblock copolymers have potential applications in the encapsulation of both hydrophobic and hydrophilic drug molecules, as evidenced from the dye encapsulation studies. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46474.     

Synthesis and characterization of amphiphilic graft copolymers with hydrophilic poly(acrylic acid) backbone and hydrophobic poly(methyl methacrylate) side chains

A series of well-defined amphiphilic graft copolymers containing hydrophilic poly(acrylic acid) backbones and hydrophobic poly(methyl methacrylate) side chains were synthesized by successive atom transfer radical polymerization followed by the selective hydrolysis of poly(methoxymethyl acrylate) backbone. Grafting-from strategy was employed for the synthesis of graft copolymers with narrow molecular weight distributions. Hydrophobic side chains were connected with the backbone through stable C-C bonds instead of ester connections. The backbone can be easily hydrolyzed to poly(acrylic acid) with HCl without affecting the hydrophobic side chains. The amphiphilic graft copolymers can form stable micelles in water. The critical micelle concentration was determined by fluorescence spectroscopy. The micellar morphologies were found to be vesicles by transmission electron microscopy and changed to spheres with the addition of NaCl.     

Synthesis of amphiphilic network copolymers based on poly(ester dimethacrylates)

Poly(ester dimethacrylate) has been synthesized by condensation of the ɛ-caprolactone-based macromonomer and 2-hydroxyethyl methacrylate with dicyclohexylmethane diisocyanate. Network copolymers of different compositions capable of swelling in water, THF, and toluene are obtained by the free-radical copolymerization of poly(ester dimethacrylate) with N-isopropylacrylamide or 2-hydroxyethyl methacrylate. The rate constants and equilibrium swelling indices of network copolymers in these solvents are measured. The amphiphilic properties of the network copolymers can vary in a wide range depending on the composition of copolymers and the nature of a hydrophilic monomer. The copolymers of poly(ester dimethacrylate) with N-isopropylacrylamide are characterized by pronounced thermal sensitivity.     

Well-defined poly(2-hydroxyethyl methacrylate) and its amphiphilic block copolymers via acidolysis of anionically synthesized poly(2-vinyloxyethyl methacrylate)

Summary A novel approach to a well-defined poly(2-hydroxyethyl methacrylate) [poly(HEMA)] and to its amphiphilic block copolymers was developed. The selective living anionic polymerization of the methacryloyl group of the bifunctional monomer 2-vinyloxyethyl methacrylate (VEMA) generated a functional polymer with a controlled molecular weight and a narrow molecular weight distribution (M_w/M_n= 1.05–1.09). This polymer is very stable under normal conditions. Being soluble in the common organic solvents, its characterization could be carried out easily. The unreacted vinyl groups in the side chains of the resulting polymer were further reacted with hydrochloric acid. This acidolysis changed poly(VEMA) to a well-defined poly(HEMA). In addition, the anionic block copolymerization of VEMA with styrene or methyl methacrylate also proceeded smoothly, generating the corresponding block copolymers. After acidolysis, these copolymers were turned into amphiphilic block copolymers containing a hydrophilic poly(HEMA) block. Received: 22 June 2001/Revised version: 15 August 2001/Accepted: 15 August 2001     

Synthesis and characterization of P(MMA-AA) copolymers for targeted oral drug delivery

This paper describes the development of pH-sensitive poly(methyl methacrylate-acrylic acid) copolymers for the enteric coating of pharmaceutical products for oral administration. To obtain the dissolution at the desired pH level, different pH-sensitive polymers are available on the market. Usually, for each desired dissolution pH, an ad hoc polymer is designed. Thus, different dissolution pH values could ask for completely different polymers. Instead, the materials proposed in this work are copolymers of the same two monomers, and the different dissolution pH was obtained by changing the volume fraction of the hydrophobic methyl methacrylate monomer to the hydrophilic acrylic acid monomer. Increasing the volumetric percentage of methyl methacrylate causes the polymer to dissolve at increasing pH, until the dissolution does not take place at all, and it is replaced by a slow swelling phenomenon. The copolymers obtained were characterized by differential scanning calorimetry, in order to evaluate their glass transition temperature, and these latter were related to %MMA. The molecular weights of the pure polymers (PAA, PMMA) were measured by intrinsic viscosity, to further validate the glass transition temperatures observed. The dissolution of the copolymers was carefully tested in buffer solutions for a dense set of pH values. A linear relationship between dissolution pH and volumetric percentage of methyl methacrylate was obtained from these measurements. As a result, for any physiological compartment, the copolymer which dissolves at the pH of interest can be easily synthesized.     

Synthesis, characterization and evaluation of amphiphilic diblock copolymer emulsifiers based on methoxy hexa(ethylene glycol) methacrylate and benzyl methacrylate

Linear, amphiphilic diblock copolymers based on the nonionic, hydrophilic monomer methoxy hexa(ethylene glycol) methacrylate (HEGMA) and the hydrophobic monomer benzyl methacrylate (BzMA) of different molecular weights and compositions were synthesized by group transfer polymerization. The molecular weights and comonomer compositions of these copolymers were characterized by gel permeation chromatography and proton nuclear magnetic resonance (¹H NMR) spectroscopy, respectively. Dynamic light scattering on aqueous solutions of the diblock copolymers indicated that all the copolymers formed aggregates whose size increased with the % w/w BzMA composition and with the overall molecular weight of the linear chains. Turbidimetry on 1% w/w aqueous copolymer solutions was used to determine the cloud points, which were found to increase with the composition in hydrophilic units and the linear chain molecular weight. After polymer characterization, xylene/water and diazinon (pesticide)/water emulsions were prepared using the above polymers as stabilizers at 1% w/w polymer concentration and at different overall organic phase/water ratios. At an organic phase/water mass ratio of 4/1, the lower molecular weight (2500 and 5000 g mol⁻¹) diblock copolymers provided stable single-phase o/w emulsions, matching the behavior of commercially available hydrophilic Pluronics.     

Temperature responsive bio-compatible polymers based on poly(ethylene oxide) and poly(2-oxazoline)s

This review covers the LCST behavior of two important polymer classes in aqueous solution, namely poly(2-oxazoline)s and systems whose thermo-responsiveness is based on their structural similarity to poly(ethylene oxide) (PEO). In order to elucidate the progress that has been made in the design of new thermo-responsive copolymers, experimental data that were obtained by different research groups are compared in detail. Copolymerization with hydrophilic or hydrophobic comonomers represents a suitable method to tune the coil to globule transition temperature of several homopolymers, and incorporation of other monomers provided further interesting features, such as pH responsiveness or sensing properties. In addition, living and controlled polymerization techniques enabled access to defined end groups and more advanced polymer architectures, such as graft copolymers or double responsive block copolymers. The effect of such structural variations on the temperature responsive behavior of the (co)polymers is discussed in detail.     

Optical application of poly(HEMA-<Emphasis Type="Italic">co</Emphasis>-MMA) containing silver nanoparticles and N,N-dimethylacrylamide

High functional ophthalmic lens materials, poly(HEMA-co-MMA)s, were prepared by the copolymerization of HEMA, MMA, NVP, EDGMA, and N,N-dimethylacrylamide in the presence of silver nanoparticles. Silver nanoparticles have antimicrobial properties and a hydrophilic monomer N,N-dimethylacrylamide has excellent biocompatibility and oxygen transmissibility. The water content was in the range of 36.63–44.45%, indicating the characteristics of general water-content contact lenses, and the refractive index was measured to be in the range of 1.423–1.435. Meanwhile, the oxygen transmissibility ranged from 10.63×10⁻¹¹ to 18.85×10⁻¹¹ (cm²/sec)(mlO₂/ml×mmHg) increasing with increasing the addition ratio of N,N-dimethylacrylamide. The polymeric materials satisfied the basic characteristics required for ophthalmic contact lenses. The polymers can be used to fabricate antimicrobial hydrogel contact lenses with high oxygen transmissibility.     

Temperature-dependent interaction parameters of poly(methyl methacrylate)/poly(2-vinyl pyridine) and poly(methyl methacrylate)/poly(4-vinyl pyridine) pairs

Temperature-dependent interaction parameters (α) of poly(methyl methacrylate)/poly(2-vinyl pyridine) (PMMA/P2VP) pair and PMMA/poly(4-vinyl pyridine) (PMMA/P4VP) pair were obtained from the SAXS profiles at various temperatures, and curve fitting to the random phase approximation theory. For this purpose, symmetric P2VP-block-PMMA and P4VP-block-PMMA copolymers were synthesized anionically. The molecular weights of both block copolymers were controlled to exhibit the disordered state over the entire experimental temperatures. We found that the value of α for PMMA/P4VP was larger than PMMA/P2VP, similar to polystyrene (PS)/poly(vinyl pyridine) pairs. However, the difference between in α between PMMA/P2VP and PMMA/P4VP was much smaller than that between PS/P2VP and PS/P4VP. This might be attributed to the hydrophilic PMMA block compared with hydrophobic PS block. Finally, the order-to-disorder transition temperature for symmetric P2VP-block-PMMA copolymers was determined by small angle X-ray scattering and birefringence methods.