聚N-异丙基丙烯酰胺/类水滑石复合水凝胶的制备及温敏性

以类水滑石(LDHs)和N-异丙基丙烯酰胺(NIPA)为原材料,采用自由基引发聚合制得了有机无机PNIPA/LDHs温度敏感复合水凝胶。 通过热重分析仪(TGA)、示差扫描量热仪(DSC)和扫描电子显微镜(SEM)等技术手段表征了材料的结构和性能。 结果表明,PNIPA/LDHs复合水凝胶在33 ℃左右可实现溶胶-凝胶的可逆性变化,LDHs质量分数基本不影响复合水凝胶的胶凝化温度和胶凝时间。 LDHs添加可使PNIPA/LDHs复合水凝胶的热稳定性较NIPA有大幅度提升。 随LDHs质量分数及n(Mg):n(Al)的增加,复合凝胶的吸热峰值稍有增加。 所合成PNIPA/LDHs复合水凝胶表面粗糙不平,具有一定的孔洞结构。     

温度和pH敏感P(NIPA-co-AA)/粘土复合水凝胶的辐射制备与表征

以N-异丙基丙烯酰胺(NIPA)作为温敏性聚合单体,丙烯酸(AA)为pH敏感性单体,有机粘土为改性剂,采用~(60)Co-γ射线为辐射源,辐射合成了P(NIPA-co-AA),粘土复合水凝胶,研究了粘土的加入对水凝胶溶胀率、温度及pH敏感性和压缩性能的影响.结果表明,P(NIPA-co-AA)/粘土复合水凝胶的溶胀性能优于P(NIPA-co-AA)水凝胶,平衡溶胀率(SR)明显提高;且复合水凝胶仍表现出明显的温度和pH敏感性;粘土的加入提高了水凝胶的压缩强度、最大压缩力和压缩屈服力等力学性能,当粘土含量为15%时,P(NIPA-co-AA)/粘土复合水凝胶的压缩强度为P(NIPA-co-AA)共聚水凝胶的2.4倍,最大压缩力为P(NIPA-co-AA)的2.1倍.     

羧甲基壳聚糖/海藻酸钠半互穿网络水凝胶的制备及性能研究

以羧甲基壳聚糖(CMC)和海藻酸钠(SA)为原料,京尼平(GP)为交联剂,制备具有pH敏感性的CMC/SA半互穿网络(semi-IPN)水凝胶.利用特性黏数、红外光谱对CMC/SA水凝胶的半互穿网络结构及形成机理进行了分析与表征;对水凝胶的力学性能进行了测试;探讨了pH值及交联剂含量对水凝胶溶胀性能的影响.结果表明,京尼平交联的CMC/SA水凝胶具有半互穿网络结构.当w(CMC)∶w(SA)=5∶5时,CMC/SA水凝胶的断裂强度达到最大值(59 MPa),分别比纯的CMC(40 MPa)和SA(36 MPa)提高了47.5%和63.9%;当SA含量为60%时,CMC/SA水凝胶的断裂伸长率达到最大值(13.0%).当pH3.0时,溶胀率随pH值的增大而减小,pH=3.0时,溶胀率最小(186%);当pH3.0时,溶胀率随pH值的增大而增大,pH=9.0时,溶胀率最大(886%).京尼平交联的CMC/SA半互穿网络水凝胶具有明显的pH敏感性、溶胀可逆性及对pH的快速响应性.     

壳聚糖-聚丙烯酸复合水凝胶的药物控制释放行为

以壳聚糖(Cs)和丙烯酸(AA)为原料,利用自由基聚合法制备了具有孔洞结构的复合水凝胶Cs-PAA,并研究了AA的量、交联剂的量、聚合温度和AA的中和度对水凝胶溶胀度的影响以及复合水凝胶对烟酸的控制释放。 结果表明,Cs-PAA复合水凝胶具有良好的pH值、离子强度敏感性,且溶胀度最高达1228 g/g,其在pH=686的缓冲溶液中的烟酸累积释放率明显大于其在pH=1.80的缓冲溶液,因此Cs-PAA水凝胶可作为肠口服药物的载体。     

羧甲基纤维素基复合水凝胶的研究及应用进展

羧甲基纤维素(CMC)水凝胶是一种具有亲水性的天然三维聚合物材料,具有高吸水性,因此以羧甲基纤维素钠制备的水凝胶安全无毒可生物降解,被广泛应用于医药、食品、农业和环境等领域,作为保鲜材料、抗菌材料、生物传感器、药物输送系统和去除重金属的吸附剂。本文按CMC复合水凝胶材料来源的不同,分类综述了大分子/CMC水凝胶、单体/CMC水凝胶和无机物/CMC水凝胶的研究进展、功能特性以及应用领域,为羧甲基纤维素复合水凝胶的研究提供一定的思路和理论依据。总结此方向研究中不同材料对羧甲基纤维素复合水凝胶性能的提升情况,同时对羧甲基纤维素水凝胶的应用前景进行了展望。     

温度及pH敏感性N-乙烯基吡咯烷酮与丙烯酸β-羟基丙酯共聚物/聚(丙烯酸)互穿网络水凝胶的合成及其性能研究

由N 乙烯基吡咯烷酮与丙烯酸 β 羟基丙酯共聚物 /聚 (丙烯酸 )所得的互穿网络水凝胶P(NVP co β HPA) /PAA具有温度及pH双重敏感特性 .在酸性条件下 ,由于P(NVP)与PAA间络合作用 ,随温度升高迅速退胀 ;在碱性条件下 ,凝胶的溶胀率远大于酸性条件下的溶胀率 ,且随温度的升高而逐渐增大     

基于壳聚糖/聚丙烯酸/纳米银的高强抗菌水凝胶

首先以丙烯酸(AA)和壳聚糖(CS)为单体、N,N′-亚甲基双丙烯酰胺(MBA)为交联剂,通过光聚合法制备了CS/PAA双网络水凝胶,然后将Ag~+以硝酸银的形式分散在水凝胶中并通过紫外光辐照获得CS/PAA/纳米银复合水凝胶,并对复合水凝胶的抗菌性能进行研究。采用红外光谱对其结构进行表征,研究单体含量对水凝胶力学性能以及溶胀行为的影响。结果表明,当丙烯酸质量分数为20%,壳聚糖质量分数为5%的情况下,水凝胶的拉伸性能最优。此外,纳米银的引入有效提高了水凝胶的抗菌性能。     

温度及pH敏感性共聚物水凝胶的合成及其对辅酶A的控制释放

以N-乙烯基吡咯烷酮(NVP)和甲基丙烯酸-N,N-二甲胺乙酯(DMAEMA)为单体,采用自由基聚合法合成了NVP与DMAEMA的共聚物及其水凝胶。研究发现共聚物的水溶液具有温度及pH双重敏感特性。相分离温度随DMAEMA含量的增加和水溶液浓度的降低而升高,随pH值的增大而减小且相变敏锐。通过对水凝胶溶胀率的考察,发现共聚凝胶在适当的单体浓度及交联剂浓度下,有较敏感的溶胀-退胀行为。在碱性条件下,共聚凝胶随温度的升高迅速退胀。pH=9时,改变温度,对辅酶A有很好的控制释放;而在酸性条件下,则无退胀行为,对辅酶A不能释放。     

含5-氟尿嘧啶的羧甲基纤维素钠/聚(N-异丙基丙烯酰胺)半互穿网络水凝胶的药物释放性能

以5-氟尿嘧啶(5-FU)为模型药物,对羧甲基纤维素钠/聚(N-异丙基丙烯酰胺)半互穿网络水凝胶(CMC/PNIPA semi-IPN)的药物释放性能进行了研究。结果表明:在37℃、pH=7.4时,药物的释放速率以及释放量都随着凝胶中羧甲基纤维素钠含量的增加而增大。在25℃时,pH对药物释放速率的影响较小;而在37℃时,药物释放速率受pH的影响较大。该凝胶体系用做5-FU的口服释放载体具有较佳的释放性能。     

腐植酸钠/聚N-异丙基丙烯酰胺/粘土杂化水凝胶的合成及脱色性能

以N-异丙基丙烯酰胺单体、粘土和腐植酸钠为原料合成了温敏腐植酸钠/聚N-异丙基丙烯酰胺/粘土（SH/PNIPA/clay）系列水凝胶。用红外光谱分析仪对其内部相互作用进行了研究,并用紫外可见分光光度计对水凝胶吸附-解吸亚甲基蓝的性能进行了测试。实验结果表明凝胶中SH与PNIPA形成了氢键;凝胶对亚甲基蓝（MB）的吸附和解吸能力受腐植酸钠的含量、粘土含量、亚甲基蓝的起始浓度和温度的影响。２％粘土含量和低温条件有利于凝胶吸附和解吸。     

Preparation and characterization of sodium carboxymethylcellulose/poly(N-isopropylacrylamide)/clay semi-IPN nanocomposite hydrogels

A new kind of pH-/temperature-responsive semi-interpenetrating polymer network hydrogels based on linear sodium carboxymethylcellulose (CMC) and poly(N-isopropylacrylamide) (PNIPA) cross-linked by inorganic clay (CMC/PNIPA/Clay hydrogel) was prepared. The temperature- and pH-responsive behaviors, the mechanical properties of these hydrogels were investigated. The CMC/PNIPA/Clay hydrogels exhibited a volume phase transition temperature around 32 °C with no significant deviation from the conventional PNIPA hydrogels. The swelling ratio of the CMC/PNIPA/Clay hydrogels gradually decreased with increasing the contents of clay. The influence of pH value on swelling behaviors showed that there is a maximum swelling ratio at pH 5.9. Moreover, the CMC/PNIPA/Clay hydrogels exhibited excellent mechanical properties with high tensile stress and elongation at break in excess of 1200%.     

A novel sodium carboxymethylcellulose/poly(N‐isopropylacrylamide)/Clay semi‐IPN nanocomposite hydrogel with improved response rate and mechanical properties

A novel semi‐IPN nanocomposite hydrogel (CMC/PNIPA/Clay hydrogel) based on linear sodium carboxymethylcellulose (CMC) and poly(N‐isopropylacrylamide) (PNIPA) crosslinked by inorganic clay was prepared. The structure and morphology of these hydrogels were investigated and their swelling and deswelling kinetics were studied in detail. TEM images showed that the clay was substantially exfoliated to form nano‐dimension platelets dispersed homogeneously in the hydrogels and acted as a multifunctional crosslinker. The CMC/PNIPA/Clay hydrogels swell faster than the corresponding PNIPA/Clay hydrogels at pH 7.4, whereas they swell slower than the PNIPA/Clay hydrogels at pH 1.2. The CMC/PNIPA/Clay nanocomposite hydrogels showed much higher deswelling rates, which was ascribed to more passway formed in these hydrogels for water to diffuse in and out. The deswelling process of the hydrogels could be approximately described by the first‐order kinetic equation and the deswelling rate decreased with increasing clay content. The mechanical properties of the CMC/PNIPA/Clay nanocomposite hydrogels were analyzed based on the theory of rubber elasticity. It was found that with increasing clay content, the effective crosslink chain density, v_e, increased whereas the molecular weight of the chains between crosslinks M_c decreased. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1546–1555, 2008     

Preparation and characterization of pH- and temperature-responsive semi-IPN hydrogels of carboxymethyl chitosan with poly (<Emphasis Type="Italic">N</Emphasis>-isopropyl acrylamide) crosslinked by clay

A new kind of pH- and temperature-responsive semi-interpenetrating polymer network hydrogel based on linear carboxymethylchitosan (CMCS) and poly (N-isopropylacrylamide) (PNIPA) crosslinked by inorganic clay was prepared. The pH-and temperature-responsive behaviors, the deswelling kinetics, and the mechanical properties of the hydrogel were investigated. The hydrogels exhibited a volume phase transition temperature around 33 °C with no significant deviation from the conventional PNIPA hydrogels. The results of the influence of pH value on the swelling behaviors showed that the minimum swelling ratios of the hydrogels appeared near the isoelectric point (IEP) of CMCS, and when pH deviated from the IEP, the hydrogels behaved as polycations or polyanions. The novel hydrogels had much higher response rate than the conventional CMCS/PNIPA hydrogels. Moreover, the semi-IPN hydrogels crosslinked by clay could be elongated to more than 800% and the elongation could be recovered almost completely and instantaneously.     

腐植酸钠/聚丙烯酰胺/粘土杂化水凝胶的研究

以过硫酸钾为引发剂、N,N′-亚甲基双丙烯酰胺为交联剂、丙烯酰胺单体和腐植酸钠、Laponite RD粘土为原料,用溶液聚合交联法合成了腐植酸钠/聚丙烯酰胺/粘土(SH-PAM-Clay)系列水凝胶.用场发射扫描电镜对其表面形貌进行了研究,并对水凝胶的吸水性和流变性能进行了测试和研究.结果表明这系列水凝胶都具有致密的网络结构和优良的吸水性能.     

Poly(vinyl alcohol)/poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide) semi-interpenetrating polymer network hydrogels with rapid response to temperature changes

A series of thermosensitive and fast-response poly(vinyl alcohol) (PVA)/poly(N-isopropylacrylamide) (PNIPA) hydrogels were prepared by incorporating PVA into cross-linked PNIPA to form a semi-interpenetrating polymeric network (semi-IPN). Compared to the conventional PNIPA hydrogel, the semi-IPN hydrogels thus prepared exhibit significantly faster response rates and undergo full deswelling in 1 min (lose about 95% water within 1 min) when the temperature is raised above their lower critical solution temperature, and have larger equilibrium swelling ratios at room temperature. These improved properties are attributed to the incorporation of PVA, which forms water-releasing channels and results in increased hydrophilicity, into the PNIPA hydrogel networks.     

快速响应的温敏性聚(N-异丙基丙烯酰胺)水凝胶的合成及表征

快速响应的温敏性聚(N-异丙基丙烯酰胺)水凝胶的合成及表征;N-异丙基丙烯酰胺;水凝胶;温敏性;快速响应     

RADIATION SYNTHESIS AND CHARACTERIZATION OF POLY(AA-co-NVP)/CLAY HYDROGELS

The pH-sensitive P(AA-co-NVP)/clay hydrogels were prepared with the monomers of acrylic acid(AA)and N-vinyl-2-pyrrolidone(NVP)based onγ-ray irradiation technique.The influence of pH values of buffer solutions and contents of clay and NVP on the equilibrium swelling ratio(SR)and compressive properties of the hydrogels was investigated in detail.The results of swelling property tests showed that,with the increase of clay content,the SR of hydrogels increases in the same buffer solution,and the SR of hydrog...     

Synthesis of Carboxymethyl Cellulose Based Drug Carrier Hydrogel Using Ionizing Radiation for Possible Use as Site Specific Delivery System

A unique natural polymer based colon specific drug carrier was prepared from carboxymethyl cellulose (CMC) and acrylic acid (AAc) in aqueous solution employing γ‐radiation induced copolymerization and crosslinking. The effect of preparation conditions such as the natural polymer content and irradiation dose on gelation process was investigated. The swelling behavior of the prepared hydrogels was characterized by investigating the time and pH dependent swelling of the (CMC/AAc) hydrogels of different CMC content. The effects of the hydrogel composition and pH of the swelling medium on the swelling indices were estimated. The results show that the increment in the CMC content in the feed solution enhances the gelation process. The results also show the dependence of the swelling indices on both hydrogel composition and pH value of the swelling medium. To evaluate the ability of the prepared hydrogel to be used as a colon‐specific drug carrier, the release profile of theophylline was studied as a function of time at pH 1 and pH 7.     

辐射交联制备改性CMC水凝胶的溶胀行为研究

利用丙烯酰胺 (AAm)接枝改性纤维素 ,然后进行羧甲基化反应得到高取代度的丙烯酰胺 羧甲基纤维素钠 (AAm CMC Na) .对该材料进行γ射线辐照制备出新型改性CMC水凝胶 .研究了这种水凝胶的溶胀动力学、交联动力学以及温度、pH值和无机盐浓度对水凝胶溶胀行为的影响 ,并与CMC Na水凝胶进行了比较 .结果表明 ,该水凝胶和CMC Na水凝胶相比 ,优点在于辐照交联所用的剂量下降 ,而且所需的CMC浓度减少 .AAm CMC Na水凝胶的溶胀度随温度升高而增大 ,在pH为 6～ 8范围内达到最大值 ,并随无机盐浓度与吸收剂量增加而下降 ,表现出较好的温度敏感性和pH敏感性 ,可望作为吸水材料和水保持剂     

Temperature sensitive poly[N-isopropylacrylamide-co-(acryloyl beta-cyclodextrin)] for improved drug release

The model drugs ibuprofen (IBU) and tegafur (T-Fu) were loaded into poly[N-isopropylacrylamide-co-(acryloyl beta-cyclodextrin)] [P(NIPA-co-A-CD)] and PNIPA hydrogels by immersing dried gels in IBU or T-Fu alcohol solutions until they reached equilibrium. Drug release studies were carried out in water at 25 degrees C. In contrast to the release time of conventional PNIPA hydrogel, that of IBU from the beta-CD incorporated hydrogel was significantly prolonged and the drug loading was also greatly increased, which may be the result of the formation of inclusion complexes between CD and ibuprofen. However, another hydrophilic drug, tegafur, did not display these properties because it could not form a complex with the CD groups. [diagram in text].