pH敏感水凝胶聚甲基丙烯酸的超声合成

在超声作用下,以甲基丙烯酸为原料,N,N’-亚甲基双丙烯酰胺为交联剂,过硫酸钾为引发剂,自由基引发聚合制备了pH敏感水凝胶聚甲基丙烯酸,采用红外光谱(FT-IR)和扫描电镜(SEM)对水凝胶分子结构与性能进行表征.在此基础上,重点研究了超声合成对于水凝胶的溶胀性能、消溶胀性能等性质的影响.实验结果表明,超声作用下合成的聚甲基丙烯酸水凝胶溶胀动力学性能以及响应灵敏性均优于常规合成方法.     

药物在pH敏感聚甲基丙烯酸-poloxamer水凝胶中的扩散行为

平衡溶胀率;药物扩散;药物在pH敏感聚甲基丙烯酸-poloxamer水凝胶中的扩散行为     

pH敏感型聚谷氨酸/透明质酸基互穿网络医用水凝胶的制备及表征

生物材料是推动生物医学领域日新月异变化的基石,医用水凝胶作为重要成员,近年来表现出蓬勃发展的态势。文章介绍了一种新型可注射的、以生物相容性方法交联的聚谷氨酸(Poly (γ-glutamic acid), PGA)/透明质酸(Hyaluronic acid, HA)复合水凝胶。研究首先采用EDC/NHS方法合成了酪胺(Tyramine,Ty)接枝聚谷氨酸的PGA-Ty前体大分子及半胱胺(Cysteamine, CA)修饰透明质酸的HA-CA前体大分子。两种前体大分子的结构分别使用核磁和红外进行了确证。得到的两种前体大分子在低浓度双氧水和辣根过氧化物酶(Horseradish Peroxidase, HRP)的共同作用下,于水相中交联得到互穿网络(Interpenetrating Network, IPN)水凝胶。实验对IPN水凝胶样品的系列性能,如平衡含水量、内部形貌、酶降解速率以及力学性能等进行了测试,并选取了盐酸四环素为药物模型对凝胶的体外药物释放行为、体外抗菌效果进行了测评。凝胶材料的细胞毒性及凝胶支架对细胞3D培养的效果证明其生物相容性优异,体外包埋的细胞经72h培养,未表现出...     

海藻酸钠/聚(N-异丙基丙烯酰胺)半互穿网络水凝胶的制备及性能研究

由海藻酸钠(SA)和聚(N-异丙基丙烯酰胺)(PNIPAAm)制得的半互穿网络水凝胶具有温度及pH敏感特性。在酸性(pH=1.3)和弱碱性条件(pH=7．4)下，研究了温度对该凝胶溶胀度的影响，结果表明，该凝胶溶胀度均随着温度的提高而下降，但在pH=1．3时，溶胀度小于PNIPAAm水凝胶的；在pH=7．4时，结果正好相反。在25℃和37℃的条件下，分别考察pH对该凝胶溶胀度的影响，结果表明，在25℃时该凝胶有良好的pH敏感性，而在37℃时，敏感性不明显。同时也发现该凝胶对pH、温度的脉冲刺激有较快的响应性。     

pH快速响应PNIPAAm-co-PAAc水凝胶的制备及溶胀动力学

pH快速响应PNIPAAm-co-PAAc水凝胶的制备及溶胀动力学;N-异丙基丙烯酰胺;pH敏感性;溶胀历史     

几类甲基丙烯酸pH—敏感水凝胶的溶胀行为研究

本文合成了以甲基丙烯酸为基础的各类ｐＨ敏感型水凝胶,并研究它们的溶胀行为。初步探索了水凝胶的组成与其ｐＨ敏感的关系,比较了阴离子型水凝胶、阳离子型水凝胶和两性水凝胶的溶胀热力学动力学行为,得出了两性水凝胶在整个ｐＨ范围内都有一定的溶胀比,且在ｐＨ中性时,其溶胀速率要高于相应的阴离子型和阳离子型水凝胶。     

CMC/PNIPAAm半互穿网络水凝胶的溶胀动力学研究

以羧甲基纤维素钠(CMC)和N-异丙基丙烯酰胺(NIPAAm)为原料,制备了具有温度和pH敏感性的半互穿网络(CMC／PNIPAAmsemi-IPN)水凝胶,并研究了水凝胶在不同温度和pH值条件下的溶胀行为。结果表明：在弱碱性(pH-7．4)条件下,凝胶的溶胀速率和溶胀度都随着凝胶中CMC含量的增加而增大;而在酸性(pH-1．O)条件下则相反。在弱碱性条件下,水分子在凝胶中的扩散行为都可用non-Fickian扩散来描述,水分子在凝胶中的扩散系数D随着凝胶溶胀速率的增大而增大;在酸性条件下,20℃时凝胶的溶胀过程符合non-Fickian扩散规律,而37℃时凝胶的溶胀过程符合Fickian扩散规律,但水分子的扩散系数D相差不大。     

丝胶基半互穿温敏凝胶的合成及其溶胀行为的研究

采用半互穿网络技术, 将具有生物相容性的丝胶蛋白(silk sericin)作为第二网络进入聚(N-异丙基丙烯酰胺)(PNIPAM)水凝胶网络中, 在水溶液中制备得到具有半互穿网络结构的丝胶基温敏水凝胶(SS/PNIPAM semi-IPNs). 采用称重法研究了产物的(消)溶胀、温度敏感性、最大溶胀度及脉冲响应行为; 利用扫描电镜(SEM), 差示扫描量热仪(DSC)和动态热机械分析仪(DMA)分别考察了产物的内部形态、热相转变行为和其储能模量随温度的变化. 结果表明: 具有较高亲水性的丝胶蛋白的引入增大了semi-IPNs水凝胶的内部孔径, 导致SS/PNIPAM半互穿水凝胶的溶胀度增加, 并且其储能模量随温度变化更明显. 相比于纯PNIPAM水凝胶, 半互穿水凝胶的消溶胀速率和低临界溶解温度(LCST)变化不大.     

PVA-PAMPS-PAA三元互穿网络型水凝胶的合成及其性能研究

以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、丙烯酸(AA)以及聚乙烯醇(PVA)为原料,制备了PVA-PAMPS-PAA三元互穿网络型(T-IPN)水凝胶.红外分析表明,PVA与PAA以及PAMPS之间形成了较强的氢键,使得PVA分子上的C—O伸缩震动吸收峰移向了低波数处.X射线衍射以及电镜分析表明,当PVA用量较低时,PVA能均匀的穿插于凝胶网络中,形成完善的互穿网络结构,当PVA用量过高时,部分的PVA结晶而使得凝胶出现相分离.研究了该三元互穿网络型水凝胶的溶胀性能,结果表明,该水凝胶的平衡溶胀比在200至340之间,并且随着AA以及AMPS用量的增加,凝胶的溶胀速率以及平衡溶胀比均升高.该三元互穿网络型水凝胶在酸性溶液中和在碱性溶液中表现出截然不同的消溶胀性能;并且随着溶液pH的升高,凝胶在pH=9.0附近出现体积突变,表现出pH敏感性.通过研究T-IPN水凝胶的抗压缩性能发现,利用线型高分子、柔性高分子网络以及刚性高分子网络制备的三元互穿网络型水凝胶能在高溶胀比下保持较高的强度.溶胀比为180的T-IPN水凝胶,其最大抗压缩强度可达12.1 MPa.进一步研究发现,凝胶的组成以及溶胀比均对凝胶的抗压缩强度和压缩应变均存在较大的影响.     

聚丙烯酰胺/聚异丙基丙烯酰胺互穿网络水凝胶的制备与性能

采用分步法用电子加速器辐射合成了聚丙烯酰胺(PAAm)/聚异丙基丙烯酰胺(PNIPAAm)互穿网络水凝胶,并考察了温度、pH值、离子强度对其溶胀性能的影响.研究表明:互穿水凝胶具有温度敏感性,且其体积相变与互穿网络中PAAm和PNIPAAm含量有关,随着网络中PAAm含量的增加水凝胶的体积相变趋于平缓,可以通过改变PAAm和PNIPAAm的组成比来控制水凝胶的体积相变行为.此外,互穿水凝胶还具有pH敏感性和一定的抗盐性.     

Temperature-pH Sensitive IPN Hydrogels Composed of Silk Sericin and Poly （N-isopropylacrylamide）

In recent years IPN hydrogels have been attracted attentions as biomedical materials1-3. Among which poly(N-isopropylacrylamide) (PNIPAAm) was frequently used to impart temperature responsive function4, 5. Many of the second components were introduced for…     

聚甲基丙烯酸基纳米水凝胶的“绿色”合成

利用原位生成的聚甲基丙烯酸甲酯种子乳胶模板以及表面活性剂与功能单体间的正负电荷作用,发展了一种可在全水相中“绿色”合成聚甲基丙烯酸(PMAA)基纳米水凝胶的新方法.利用动态光散射法、ξ-电位测定、FTIR和TEM对纳米水凝胶的尺寸及其分布、表面电荷、组成、形态、结构和pH响应行为进行了表征.结果表明,PMAA基纳米水凝胶具有聚甲基丙烯酸甲酯内核和交联聚甲基丙烯酸外壳的核壳结构.当甲基丙烯酸(MAA)的用量由2 mL增至3 mL时,PMAA基纳米水凝胶的尺寸变大.当MAA的用量增加至5 mL时,反应体系中除了生成PMAA基纳米水凝胶外,还生成了PMAA次级粒子.PMAA基纳米水凝胶表现出良好的pH响应性:当介质的pH值由2增加至7时,其流体力学体积扩张了近80倍.     

Interpenetrating Polymer Networks of Uralkyd Resin Based on Hydrogenated Castor Oil and Poly(Butyl Acrylate)

Abstract

Semi‐ and full‐interpenetrating polymer networks (IPNs) of uralkyd (UA) resin based on hydrogenated castor oil and poly(butyl acrylate) (PBA) were prepared by the sequential mode of synthesis. These IPNs were characterized for their resistance to thermal behavior, swelling (%), and mechanical properties. The morphology of the IPNs was studied by scanning electron microscopy (SEM). The effect of the variations of the blend ratios on the above‐mentioned properties was examined. The mechanical properties significantly enhanced by increasing UA component in the blend. Full‐IPNs exhibited higher apparent densities, mechanical properties, and thermal stability than the corresponding semi‐IPNs.     

聚甲基丙烯酸与修饰聚丙烯酰胺间的络合作用

利用荧光各向异性,荧光探针和荧光猝灭等静态光物理技术研究了稀水溶液中聚甲基丙烯酸（ＰＭＡＡ）与阳离子修饰聚丙烯酰胺（ＱＣＰＡＭ）间的络合作用。结果表明：在ｐＨ＝２－８范围内,ＰＭＡＡ与ＱＣＰＡＭ之间发生明显络合,但以ｐＨ为４时络合作用最大,最佳络合本比为１：１（单体单元比）,络合作用的发生大大地改变了ＰＭＡＡ的构象行为,ＰＭＡＡ构象对ｐＨ和络合作用的双重依赖性有可能在新型“智能”凝胶的设计合成上获     

新型聚合物互穿网络PP／PnBA的合成与表征

采用原位聚合法在聚丙烯微孔膜基材内复合聚丙酸丁酯制备了一种新型聚合物互穿网络ＰＰ／ＰｎＢＡ。用傅立叶扫描红外光谱，偏光显微镜，扫描电镜，Ｘ射线光电子能谱，广角Ｘ射线衍射及力学拉伸等手段进行了表征。发现复合膜表面ＰｎＢＡ的多少依赖于聚丙烯微孔膜基材表面微孔的量及分情况，复合膜基本上保持了聚丙烯微孔膜基材的骨架结构，交联聚丙烯酸了脂填入了几乎全部微孔，成为一个与聚丙烯相互穿的连续相，形成了真正互穿网络     

PMAA纳米水凝胶的水相制备

利用表面活性剂间的疏水作用以及表面活性剂与单体间的氢键作用,促使甲基丙烯酸(MAA)单体在原位生成的聚甲基丙烯酸甲酯(PMMA)种子乳胶表面的选择性聚合,实现了PMAA纳米水凝胶的水相"绿色"制备。利用动态光散射、傅里叶红外光谱、透射电子显微镜表征了PMAA纳米水凝胶的尺寸、组成、形貌和pH响应性。研究了聚氧乙烯失水山梨醇单月桂酸酯(吐温20)的用量、N,N’-亚甲基双丙烯酰胺(MBA)的用量、MAA的用量和加入方式、十二烷基硫酸钠(SDS)的补加速率等对PMAA纳米水凝胶的尺寸和溶胀性能的影响。结果表明:PMAA纳米水凝胶为核-壳结构;随着MBA用量的减小、吐温20用量的增加、MAA用量的增加,PMAA纳米水凝胶的尺寸和溶胀比均增大;当采用半连续加入MAA时,PMAA纳米水凝胶的尺寸和溶胀比变小;当SDS的补加时间由60min延长到100min时,PMAA纳米水凝胶的尺寸逐渐变小。PMAA纳米水凝胶具有良好的pH响应性,当介质的pH从1增加到6时,其流体力学体积扩张了64倍。     

聚甲基丙烯酸纳米水凝胶的水相合成及其磁性功能化

利用十二烷基硫酸钠/吐温20复配表面活性剂和原位生成的聚甲基丙烯酸甲酯(PMMA)种子乳胶,发展了一种可在全水相中"绿色"合成较高浓度的聚甲基丙烯酸(PMAA)纳米水凝胶的新方法.以PMAA纳米水凝胶为前驱体,采用原位氧化沉淀法制备了磁性PMAA纳米微球.利用动态光散射法、FTIR分析、TEM观察、振动样品磁强计测试(VSM)、热重分析(TG)等对纳米水凝胶和磁性微球进行了表征,并探讨了PMAA纳米水凝胶的形成机理.结果表明,吐温20与MAA和PMAA间的氢键作用,促成了交联PMAA/吐温20复合物层在PMMA种子乳胶表面的选择性生长,导致生成了具有核壳结构的PMAA纳米水凝胶.PMAA纳米水凝胶表现出良好的p H响应性,当介质的p H值由1增加至6时,其流体力学体积扩张了近50倍.磁性PMAA纳米微球具有超顺磁性,其饱和磁化强度高达50 A·m~2/kg.     

Binding of a surfactant counterion to low-charge-density poly(acrylic acid) and poly(methacrylic acid)

The binding of a cationic surfactant, dodecylpyridinium (C12Py) chloride, with a low-charge-density poly (methacrylic acid) (PMA) was investigated in buffer solutions under the condition of constant pH. The binding isotherms with PMA consisted of two and three steps at a pH lower and higher than 3.2, respectively. Bindings in the first step were independent of pH and this step was considered to correspond to the solubilization of the hydrocarbon chains of C12Py into the nonpolar region of the compact form of PMA. This is the indication of the compact form from the binding isotherm. At pH higher than 3.2, the second step was discriminated and it depended on the pH. In the third step, a sharp rise in the degree of binding (β) was observed accompanying the solubilization of the precipitates of the PMA–C12Py complex. The binding with poly(acrylic acid) (PAA) and PMA in conventional unbuffered NaCl solutions was also examined and the pH profile of the solution during the binding process was determined. In the case of unbuffered NaCl solutions, the binding with PAA took place cooperatively at the critical association concentration (cac). The binding isotherm consisted of two steps and the pH decreased with the increase in β. The binding isotherm of PMA, on the other hand, consisted of three steps: the pH decreased slightly in the first step and considerably in the second step with the increase in β but it increased with β in the third step, exhibiting a pH minimum around 3.2. The binding in the first step coincided with that obtained in the buffered solutions. Linear relationships between β and the pH were found for both polymers. In the case of PMA, no cac was observed in both buffered and unbuffered NaCl solutions. Received: 24 January 2001 Accepted: 23 May 2001     

The synthesis and characterization of monodisperse poly(acrylic acid) and poly(methacrylic acid)

A number of polyacrylic (PAA) and polymethacrylic (PMAA) acids have been synthesized by living anionic polymerization of the monomeric tert-butyl esters followed by subsequent hydrolysis of the corresponding polyesters. The necessary precautions were taken in order to assure good molecular weight control, as well as high yields in the polymerization reactions. The intermediate and final polymers were characterized by gel permeation chromatography and NMR-H¹ spectrometry.     

Preparation and Characterization of pH-sensitive Hydrogel Film of Chitosan/Poly(acrylic acid) Copolymer

A hydrogel film of chitosan/poly(acrylic acid) (CS/PAAc) copolymer with the property of pH sensitivity, was prepared by irradiating the chitosan film, which was then swelled by aqueous AAc solutions of different concentrations. The effects of the feed ratio of chitosan and AAc on the properties of the hydrogels, such as swelling ratio and pH-sensitivity, were determined. Fourier transform infrared (FT-IR) spectroscopy was applied in the attenuated total reflectance (ATR) mode for analyzing the structure change of the hydrogels after the treatment in buffer solutions of different pHs.