聚（丙烯酸-CO-丙烯酰胺）／腐殖酸钠／高岭土复合高吸水性树脂的制备及溶胀行为

以N,N′-亚甲基双丙烯酰胺为交联剂、过硫酸铵为引发剂,采用水溶液聚合法合成了聚(丙烯酸-co-丙烯酰胺)/腐殖酸钠/高岭土多功能复合高吸水性树脂。研究了腐殖酸钠和高岭土含量对吸水倍率的影响,同时考察了该树脂的吸水速率及溶液pH值和不同阴阳离子对吸水倍率的影响。结果表明,在腐殖酸钠∶高岭土=2∶3(质量比)时树脂具有最高的吸水倍率,其吸蒸馏水和0.9%(质量分数)NaCl溶液分别达到450 g/g和39 g/g。     

聚乙烯醇/聚丙烯酸/羟基磷灰石复合高吸水性树脂的制备及溶胀行为

以聚乙烯醇(PVA)、部分中和的丙烯酸(AA)和羟基磷灰石(HA)为原料,过硫酸铵(APS)为引发剂,N,N′-亚甲基双丙烯酰胺(MBA)为交联剂,采用水溶液聚合法制备了聚乙烯醇/聚丙烯酸/羟基磷灰石(PVA/PAA/HA)复合高吸水树脂。考察了PVA用量对吸水性能的影响,研究了树脂在不同pH值溶液和不同阳离子盐溶液中的溶胀行为。结果表明,引入适量的PVA有利于树脂吸水性能的改善;树脂在pH=4～11较宽的范围内都能保持较高的吸水倍率,在CaCl2溶液中的溶胀动力学行为表现出明显的"过溶胀平衡现象"。     

Polyampholytes superabsorbent nanocomposites with excellent gel strength

A series of novel polyampholyte superabsorbent nanocomposites with excellent gel strength were synthesized by in situ solution polymerization in aqueous solution. Acrylic acid and acryloyloxyethyl trimethyl ammonium chloride (DAC) were employed as ionic monomers and montmorillonite (MMT) was used as inorganic component. The addition of cationic component could supply the positive charge in the network of nanocomposite and promote the formation of nanostructure of composites due to the interaction between DAC and clay platelets. The performance of polyampholyte nanocomposites were investigated and the result showed that the gel strength of nanocomposite hydrogel in distilled water and 0.9 wt% NaCl solution could reach 198.85 and 204.23 mJ/g, respectively, which were 13 times of the gel strength of matrix. The investigation of swelling behaviors showed that the nanocomposites had particular swelling behaviors of polyampholytes hydrogel in solution with different pH values and concentration of NaCl.     

疏水改性聚N-异丙基丙烯酰胺的性能及对溶液组成的依赖性

采用自由基胶束水溶液聚合方法制备了疏水改性聚N-异丙基丙烯酰胺水凝胶(P(NIPA-co-MA／EA／BA／DA)),研究了该类水凝胶和PNIPA水凝胶在去离子水及NaCl、Na2SO4、乙醇水溶液中的溶胀行为及与温度的关系。结果表明,聚合物水凝胶在水溶液中的行为与凝胶化学结构、温度、水溶液中的溶质的种类和含量有关。     

PNIPAAm/CMC半互穿网络水凝胶的合成及性质

以N-马来酰化壳聚糖为交联剂,N-异丙基丙烯酰胺(NIPAAm)为单体,羧甲基纤维素钠(CMC)为半互穿材料,在水溶液中通过自由基聚合制备了PNIPAAm/CMC半互穿网络水凝胶.所合成的水凝胶的低临界溶解温度(LCST)在33℃左右,CMC的加入对水凝胶的LCST无显著影响,但随着CMC用量的增加,水凝胶的温度敏感性...     

Thermosensitive poly (N-isopropylacrylamide) hydrophobic associated hydrogels: optical, swelling/deswelling, and mechanical properties

Thermosensitive hydrophobic associated hydrogels (NI-HA gels) were prepared by free radical micellar copolymerization in aqueous solution of N-isopropylacrylamide, a small amount of hydrophobic monomer octylphenol polyoxyethylene (4) acrylate (OP4~AC), and nonionic surfactants. The mechanical properties, swelling/deswelling behaviors, and optical transmittances of NI-HA gels were studied. As OP4~AC content varied, both mechanical properties and swelling behaviors of gels changed greatly. The temperature-induced changes in optical transmittance and deswelling tests showed that NI-HA gels had rapid temperature responsive rate and clear volume phase transitions at around 34 °C, and these properties had almost no concern with OP4~AC content. Furthermore, NI-HA gels also possessed extremely sensitive swelling/deswelling switch behaviors and well swelling stabilities.     

CMS-g-PAA高吸水性复合材料的制备及性能研究

以废弃全棉面膜基布(CMS)和丙烯酸(AA)为原料,采用自由基溶液聚合法制备CMS-g-PAA复合高吸水性材料,并用红外光谱(FTIR)进行表征。研究了吸水性、保水性及反复吸放液性能,采用准一级、二级动力学模型对其吸水溶胀过程进行模拟研究。结果表明,全棉面膜基布和丙烯酸单体之间发生了接枝共聚反应,所合成的CMS-g-PAA复合材料在去离子水和0.9%(质量分数)NaCl溶液的吸水倍率分别可达211.3g/g和45.5g/g,且溶胀过程符合准二级动力学吸附模型。在较高温度和一定压力下,CMS-g-PAA均具有良好的保水性能。反复吸放液性能测试表明循环8次后,去离子水和0.9%(质量分数)NaCl溶液的吸水倍率分别保持了最大吸水倍率的64.9%和44.4%。     

疏水改性PNIPA水凝胶的制备及在表面活性剂溶液中的性能

采用水溶液和水溶液胶束自由基聚合方法分别制备了聚N-异丙基丙烯酰胺水凝胶(PNIPA)和疏水改性PNIPA水凝胶：聚N-异丙基丙烯酰胺-co-丙烯酸甲酯(MA)／丙烯酸乙酯(EA)／丙烯酸丁酯(BA)／丙烯酸十二酯(DA)水凝胶。研究了凝胶的微观结构及不同结构的水凝胶在表面活性剂溶液中的溶胀行为。结果表明,PNIPA与疏水改性PNIPA水凝胶有着不同的微观形态结构;与PNIPA水凝胶相比,疏水改性PNIPA水凝胶在十二烷基硫酸钠(SDS)和十六烷基三甲溴化铵(CTAB)水溶液中的溶胀率增大,温敏性增强。疏水改性水凝胶在溶液中的溶胀行为与凝胶化学结构、溶液组成有关。对于疏水改性丙烯酸酯-NIPA共聚水凝胶,其溶胀率随丙烯酸酯碳链长度的增加而降低,在SDS溶液中的相转变温度远比CTAB溶液中的高,突变温度区间更宽。     

PAA-Na/PVA半互穿网络水凝胶的离子强度及pH敏感性

采用水溶液聚合法制备了聚丙烯酸钠(PAA-Na)/聚乙烯醇(PVA)半互穿网络水凝胶,研究了水凝胶在不同pH溶液、不同浓度NaCl与CaCl2溶液中的溶胀行为,结果表明,溶胀比随丙烯酸含量增大而增加,在碱性溶液中的溶胀度明显高于酸性溶液,溶胀平衡凝胶在酸性及碱性条件下均出现收缩,在pH=2和pH=12溶液中反复交换时,表现出可逆溶胀-退溶胀性能,具有较好的pH敏感性,凝胶在不同浓度NaCl与CaCl2溶液中溶胀性表明,溶液的离子强度及阳离子的电荷数对凝胶溶胀行为有较大影响。     

Synthesis,characterization, biodegradability and biocompatibility of a temperature-sensitive PBLA-PEG-PBLA hydrogel as protein delivery system with low critical gelation concentration

Temperature-sensitive hydrogels were designed using a series of A-B-A triblock copolymers consisting of poly (ethylene glycol) (PEG) with different molecular weights as the hydrophilic block B and poly (β-butyrolactone-co-lactic acid)(PBLA) with varying block lengths and composition as the hydrophobic block A. The triblock copolymers were synthesized by ring-opening polymerization (ROP) of β-BL and LA in bulk using PEG as an initiator and Sn(Oct)₂ as the catalyst. Their chemical structure and molecular characteristics were determined by NMR, GPC and DSC, and the relationship between structure and phase behaviors in aqueous solutions was investigated as well. It was found that the phase behaviors in aqueous solutions including critical micelle concentration (CMC), sol-gel-sedimentation phase transition temperature, gel window width and critical gelation concentration (CGC) are largely dependent on the molecular weight and block length ratio of PEG/PBLA. Most importantly, they show a very low CGC ranging from 4 to 8?wt% because of the introduction of β-BL. Furthermore, the biodegradability and biocompatibility of the hydrogels were evaluated. Finally, lysozyme as a model protein was used to evaluate the ability to deliver protein drugs in a sustained release manner and biologically active form. All results demonstrated that the temperature-sensitive in situ forming hydrogel has a promising potential as sustained delivery system for protein drugs.     

辉光放电电解等离子体法制备蛭石/聚丙烯酸高吸水性复合材料及其溶胀性能

在水溶液中,以丙烯酸（AA）和蛭石（VMT）为原料,N,N’-亚甲基双丙烯酰胺（MBA）为交联剂,用辉光放电电解等离子体（GDEP）技术引发一步制备蛭石/聚丙烯酸高吸水性复合材料。采用FTIR、XRD对蛭石/聚丙烯酸的结构进行了表征,探讨了GDEP引发聚合和溶胀动力学行为的机制,研究了pH值和盐浓度对蛭石/聚丙烯酸平衡溶胀率的影响。结果表明,蛭石/聚丙烯酸高吸水性复合材料在蒸馏水中2 h达溶胀平衡,溶胀过程遵循拟二级动力学模型;该复合材料具有pH敏感性、盐敏感性和可逆溶胀-消溶胀开关行为,其在单价阳离子溶液中的平衡溶胀率比二价阳离子溶液中的更高。     

阴离子型高吸水性树脂凝胶的响应性能

以CMCTS-g-PAA和CMCTS-g-(PAANa-co-PVP)两类羧甲基壳聚糖改性阴离子型高吸水性树脂凝胶为研究对象,对其所吸收液体性能变化的响应性进行了研究。研究发现,阴离子型高吸水性树脂随乙醇/水混合溶剂中乙醇体积分数(φ)的增大发生体积相转变;随树脂结构中链段极性的增大,凝胶相变点相应的(φ)值降低;并随所吸收液体中低极性乙醇含量的增大,-COO-之间的相互排斥作用减弱,树脂的吸水速率降低。当研究溶液离子强度对树脂溶胀性能的影响时发现,1/S值较大时,离子强度与Q5/3成正比;但离子浓度较大时,Q5/3与1/S的线性关系消失。此外所吸收溶液的pH值对树脂的吸收率也有很大的影响。     

Tuning PEG-DA hydrogel properties via solvent-induced phase separation (SIPS)()

Poly(ethylene glycol) diacrylate (PEG-DA) hydrogels are widely utilized to probe cell-material interactions and ultimately for a material-guided approach to tissue regeneration. In this study, PEG-DA hydrogels were fabricated via solvent-induced phase separation (SIPS) to obtain hydrogels with a broader range of tunable physical properties including morphology (e.g. porosity), swelling and modulus (G'). In contrast to conventional PEG-DA hydrogels prepared from an aqueous precursor solution, the reported SIPS protocol utilized a dichloromethane (DCM) precursor solution which was sequentially photopolymerized, dried and hydrated. Physical properties were further tailored by varying the PEG-DA wt% concentration (5 wt%-25 wt%) and M(n) (3.4k and 6k g mol (-1)). SIPS produced PEG-DA hydrogels with a macroporous morphology as well as increased G' values versus the corresponding conventional PEG-DA hydrogels. Notably, since the total swelling was not significantly changed versus the corresponding conventional PEG-DA hydrogels, pairs or series of hydrogels represent scaffolds in which morphology and hydration or G' and hydration are uncoupled. In addition, PEG-DA hydrogels prepared via SIPS exhibited enhanced degradation rates.     

聚丙烯酸/活性炭复合凝胶的制备及溶胀行为

采用自由基溶液聚合的方法,以过硫酸铵(APS)为引发剂,N,N′-亚甲基双丙烯酰胺(NNMBA)为交联剂,制备了聚丙烯酸(PAA)复合活性炭凝胶(PAA/AC)。考察了凝胶在生理盐水和不同pH值缓冲溶液中的平衡溶胀比及溶胀动力学,结果表明,活性炭能有效提高PAA凝胶的平衡溶胀比。蒸馏水中PAA/AC凝胶的平衡溶胀比可达到303(g/g),约为PAA凝胶平衡溶胀比的2.3倍;生理盐水(0.9%g/mL NaCl水溶液)中PAA/AC凝胶的平衡溶胀比可达到60(g/g),约为PAA凝胶平衡溶胀比的2.4倍;在实验设计的pH范围内PAA/AC凝胶的平衡溶胀比比PAA凝胶更高,具有更好的pH值敏感特性。     

Preparation and characterization of pH- and temperature-responsive nanocomposite double network hydrogels

A methodology is described for the preparation of pH- and temperature-responsive double network (DN) hydrogels with poly(N-isopropylacrylamide) (PNIPAM) as a tightly crosslinked 1st network, polyacrylic acid (PAA) as a loosely crosslinked 2nd network and graphene oxide (GO) as an additive. GO sheets were first prepared via an oxidation reaction and then dispersed in NIPAM aqueous solution via silanization. Free-radical polymerization of NIPAM was carried out at 20 °C in a water bath, and then subjected to UV light, leading to the formation of pH- and temperature-responsive PNIPAM/AA/GO DN hydrogels. The effects of GO sheets and AA contents on various physical properties were investigated. Results show that PNIPAM/AA/GO hydrogels undergo a large volumetric change in response to temperature. It also exhibits significantly fast swelling/deswelling compared with conventional PNIPAM hydrogel. Moreover, the PNIPAM/AA/GO hydrogels have a much better mechanical property than the conventional PNIPAM hydrogels.     

Preparation and characterization of hydrophobically modified polyacrylamide hydrogels by grafting glycidyl methacrylate

A modified polyacrylamide (PAM-g-GMA) has been prepared by ring-opening reaction of glycidyl methacrylate (GMA) monomer grafted onto the –COO⁻ groups of partially hydrolytic polyacrylamide (PAM) chain. The modified polyacrylamide hydrogels were obtained via a free radical polymerization of PAM-g-GMA without adding any a crosslinker using potassium persulfate (KPS), as initiator, and triethanolamine (TEA), as a coupling agent in aqueous solution. The molecular structure of PAM-g-GMA was characterized by FT-IR, ¹H-NMR, and the thermal behaviors of hydrogels were studied by DSC. Furthermore, the swelling property and compressive properties of PAM-g-GMA hydrogels were investigated. The results show that the modified polyacrylamide hydrogels exhibit a remarkable hydration-dehydration change in response to pH in aqueous media and also undergo dramatic increase in volume with increasing temperature. So the modified polyacrylamide hydrogels will have promising and wide applications such as pharmaceutical use, water retention, electrophoretic media and so on.     

Swelling behavior of polyacrylamide/laponite clay nanocomposite hydrogels: pH-sensitive property

In this study, an investigation is carried out on the influence of varying clay contents (25–43%), pH values (2–11 buffer solutions), heat treatment, temperatures (25–60 °C) and ionic strengths (saline solution, 10^?7–0.1 M) on the water absorbency of polyacrylamide (PAAm)/laponite nanocomposite (NC) hydrogels in the absence of polyelectrolyte. For the influence of pH value on swelling behaviors, a maximum swelling ratio occurs at pH 11. Heat treatment of the hydrogels significantly improved the swelling capacity and created an obvious pH sensitive area (pH 3–4). The swelling capacity of the hydrogels was enhanced by increasing the temperature of the absorbing media. The results of swelling at different ionic strengths also indicate that the ionic strength can considerably weaken the swelling abilities of the NC hydrogels.     

The synthesis,swelling behaviour and rheological properties of chemically crosslinked thermosensitive copolymers based on <Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide

In this contribution thermosensitive polymer matrices based on N-isopropylacrylamide have been developed. The hydrogels were prepared by photopolymerisation of N-isopropylacrylamide and 1-vinyl-2-pyrrolidinone in appropriate amounts of distilled water. The monomers were cured using a UV-light sensitive initiator called 1-hydroxycyclohexylphenylketone. These copolymers were crosslinked using ethylene glycol dimethacrylate and poly(ethylene glycol) dimethacrylate with molecular weights 600 and 1,000, at 0.1 wt% of the total monomer content. The chemical structure of the xerogels was characterised by means of Fourier transform infrared spectroscopy (FTIR) and the transition temperature of the hydrogels was determined using modulated differential scanning calorimetry (MDSC). By altering the feed ratio, hydrogels were synthesised to have lower critical solution temperatures (LCST) around 37 °C. This ability to shift the phase transition temperature of the gels provides excellent flexibility in tailoring transitions for specific uses. The samples synthesised with PEG1000DMA crosslinking agents absorbed over 18 times their weight in water, while maintaining good gel integrity thus falling marginally short of being characterised as superabsorbent. Each of the samples showed similar deswelling behaviour at 37 °C. Rheological studies showed that increasing the molecular weight of the crosslinking agent caused an increase in hydrogel strength.     

壳聚糖-g-聚丙烯酸/海泡石复合高吸水性树脂的制备及吸水性能

以海泡石、壳聚糖和丙烯酸为原料,在水溶液中通过接枝共聚反应合成了壳聚糖接枝共聚丙烯酸/海泡石复合高吸水性树脂。研究了交联剂、引发剂、丙烯酸和壳聚糖质量比、海泡石用量和不同脱水方法对复合树脂吸水倍率的影响,测定了不同海泡石含量复合高吸水性树脂的吸水速率。红外光谱分析结果表明,丙烯酸、壳聚糖和海泡石共同参与了接枝聚合反应。当海泡石含量为10%时,不仅可以提高复合吸水树脂的吸水倍率,而且还可以提高吸水速率。     

PVA/P(AA-AM)复合水凝胶的制备及性能

采用水溶液聚合方法合成了不同组成的丙烯酸-丙烯酰胺共聚物(P(AA-AM))。将聚乙烯醇(PVA)与所合成的P(AA-AM)共混,以戊二醛为交联剂,制备出了不同结构的PVA/P(AA-AM)复合水凝胶。采用扫描电镜观察了凝胶形貌,研究了复合水凝胶的结构与性能关系。结果表明,复合水凝胶溶胀性能与所用交联剂加量有关,复合水凝胶的溶胀度随着交联剂加量增加先增大后减小,在交联剂加量为0.5%时水凝胶溶胀度达到最大值。复合凝胶中的聚合物组成对溶胀度影响显著,随着P(AA-AM)含量提高,水凝胶的溶胀度逐渐增大。适当结构的复合水凝胶具有pH敏感性,敏感程度随着凝胶中P(AA-AM)含量的增加而增强。