P(AA-DAC)两性聚电解质水凝胶的合成及性质

以丙烯酸(AA)和丙烯酰氧乙基三甲基氯化铵(DAC)为单体, 采用水溶液聚合法制备了P(AA-DAC)聚电解质水凝胶. 采用红外光谱和核磁共振等方法对其结构进行了表征. 研究了不同组成比的聚电解质水凝胶在去离子水、不同pH值溶液以及不同离子强度盐溶液中的溶胀行为. 研究结果表明, 摩尔比为1∶1的聚电解质水凝胶表现出典型的两性聚电解质凝胶的溶胀行为. 离子强度对其溶胀行为有着显著影响, 在溶液离子强度较高时, 凝胶网络的溶胀主要受溶剂向凝胶内部扩散所控制, 满足Fick型扩散规律n≤0.5, 随着溶液离子强度的增加, 凝胶网络平衡含水量增加, 扩散系数增大.     

离子强度对P(HEMA-co-MMA)水凝胶溶胀性能及水的状态的影响

对甲基丙烯酸-β-羟乙酯(HEMA)与甲基丙烯酸甲酯(MMA)共聚水凝胶扩散行为、聚合物-溶剂相互作用及水的状态进行了研究。考察了不同NaCl离子强度下水凝胶平衡含水率、扩散系数及聚合物-溶剂相互作用参数的变化关系。研究结果表明,随着NaCl离子强度增大,平衡含水率降低,扩散系数下降,聚合物-溶剂相互作用参数升高。通过DSC测定了水凝胶中冻结水和非冻结水的组成。     

温度/pH敏感性接枝共聚物水凝胶P(DMAEMA-g-NIPAM)的 合成及性质研究

利用大分子单体技术, 采用自由基溶液聚合合成了温度/pH敏感性聚甲基丙烯酸-N,N-二甲氨基乙酯接枝聚N-异丙基丙烯酰胺[P(DMAEMA-g-NIPAM)]水凝胶. 用红外光谱及扫描电镜对凝胶的组成及形貌进行了表征. 凝胶的去溶胀和溶胀动力学研究表明, 所合成的凝胶具有温度和pH敏感性. 与传统的聚丙烯酸系水凝胶相比, P(DMAEMA-g- NIPAM)具有相反的pH敏感性; P(DMAEMA-g-NIPAM)凝胶在55 ℃时具有较快的去溶胀速率, 随着凝胶中接枝链PNIPAM量的增加, 凝胶的去溶胀速率加快.     

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(英文)

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.     

P(AMPS-co-BMA)水凝胶的电场敏感性及电刺激响应机理

以离子型单体2-丙烯酰胺-2-甲基丙磺酸(AMPS)及非离子型单体甲基丙烯酸丁酯为原料,偶氮二异丁腈为引发剂,N,N′-亚甲基双丙烯酰胺为交联剂,N,N-二甲基甲酰胺为溶剂,通过自由基聚合合成了一系列聚离子浓度不同的聚(2-丙烯酰胺-2-甲基丙磺酸-co-甲基丙烯酸丁酯)电场敏感性水凝胶.研究了其在去离子水及NaCl溶液中的溶胀行为.结果表明,该水凝胶在去离子水中的平衡溶胀度在236.4~298.5之间,其溶胀速率随着AMPS用量的增加而增加;并且随着凝胶内部聚离子浓度的增加,凝胶在NaCl溶液中的消溶胀速率及消溶胀度逐渐减小.凝胶的电刺激响应性能研究结果表明,在电场存在下,凝胶在NaCl溶液中的溶胀行为与凝胶内部聚离子浓度和溶液中NaCl浓度的相对大小有关,当凝胶内部聚离子浓度大于溶液中NaCl浓度时,凝胶溶胀,反之则凝胶消溶胀;而且,凝胶在电场作用下的偏转行为同样与凝胶内部聚离子浓度和溶液中NaCl浓度的相对大小有关,当凝胶内部聚离子浓度大于溶液中NaCl浓度时,偏向阴极,反之则凝胶偏向阳极.另外,在电场存在下,凝胶在NaCl溶液中的电偏转速度与环境温度密切相关.     

pH敏感的聚(L-谷氨酸)-交联聚丙烯酸水凝胶的合成与性能研究

通过在聚L-谷氨酸侧链部分接枝甲基丙烯酸2-羟乙酯得到含有双键的聚(L-谷氨酸),将其与丙烯酸共聚得到由聚(L-谷氨酸)侧链接枝并交联聚丙烯酸的pH敏感水凝胶.研究水凝胶在不同pH的缓冲溶液中的溶胀性、溶胀动力学,并通过SEM观察水凝胶的微观结构.结果表明,水凝胶在低pH环境下的溶胀率明显低于高pH环境中的溶胀率,不同...     

pH响应性聚膦腈水凝胶的制备与表征

以N,N-二甲基乙二胺为阳离子型取代基,甲基丙烯酸羟乙酯或烯丙胺为共取代基,制备了同时带有pH响应性侧基和不饱和双键侧基的聚膦腈.该聚合物的结构和组成经1H NMR和FTIR确认后,通过自由基引发交联得到聚膦腈凝胶.凝胶在不同介质中的吸水率测试结果表明,该阳离子型聚膦腈水凝胶的溶胀行为受聚合物侧基组成、介质pH、离子强度和阴离子价态影响显著,有望与葡萄糖氧化酶结合后实现对胰岛素的葡萄糖响应释放.     

P(NVP-co--βHPAT)/CS半互穿网络凝胶的合成与环境响应特性

以壳聚糖(CS),N-乙烯基吡咯烷酮(NVP)和丙烯酸β-羟基丙酯(β-HPAT)为原料,合成了半互穿网络(Semi-IPN)水凝胶P(NVP-co-β-HPAT)/CS(简称Semi-IPNH),其结构经FT-IR,TG和SEM表征.对Semi-IPNH的温度与pH敏感环境响应特性进行了研究,考察了温度、pH值、离子强度以及单体配比等对其溶胀度的影响.结果表明,Semi-IPNH具有较敏锐的温度及pH敏感特性;在离子强度小于2.0 mol·L-1时,对Semi-IPNH的溶胀行为影响不明显;随着NVP含量的增大,凝胶的溶胀率增大.在20 ℃或45 ℃的去离子水及pH 3.0或pH 8.0的柠檬酸/磷酸氢二钠缓冲溶液中,Semi-IPNH的溶胀-收缩具有可逆性.     

聚(N,N′-二乙基丙烯酰胺)水凝胶的制备及其溶胀动力学

以N,N′-二乙基丙烯酰胺(DEA)为单体,偶氮二异丁腈(AIBN)为引发剂,分别采用疏水性的1,2-二乙烯苯(DVB)和水溶性的N,N′-亚甲基双丙烯酰胺(BIS)为交联剂制备了温度敏感水凝胶聚(N,N′-二乙基丙烯酰胺)(PDEA).制得的PDEA水凝胶的低临界溶解温度(LCST)在30 ℃附近,初步讨论了交联剂的用量和性质对水凝胶性能的影响.并对其在不同温度下达到溶胀平衡时的溶胀比,去溶胀动力学及干凝胶的再溶胀动力学过程进行了研究.     

含有4,4′-双(甲基丙烯酰胺基)偶氮苯水凝胶的合成及其在结肠位药物释放的动物实验

合成了不同链长的甲基丙烯酸酯、甲基丙烯酰胺及丙烯酸与4,4′-双(甲基丙烯酰胺基)偶氮苯交联共聚的功能凝胶.三维网络结构通过压缩弹性模量、有效交联密度及聚合物与溶剂间的相互作用参数进行了表征.主要研究了这类凝胶在pH2.2和pH7.4的缓冲溶液的平衡溶胀特性及其偶氮交联基团在体内的降解行为,并讨论了其降解机制.凝胶在胃部的性能稳定,既不发生溶胀,亦不发生降解;但在盲肠内偶氮交联基因可发生降解.其降解率与凝胶的平衡溶胀程度有一个很好的关联:交联程度、疏水基侧链的长度及含量对凝胶溶胀行为的影响结果与这些因素对偶氮交联基团体内降解的影响结果完全一致.通过调节这些因素不仅可以控制凝胶的溶胀程度,而且可以控制偶氮交联基团在体内的降解行为.     

Thermodynamic Study of Poly(vinyl pyrrolidone) in Water/Dimethyl Sulfoxide Solutions by Viscometry

In this work, the intrinsic viscosities of poly(vinyl pyrrolidone) with a molar mass of 58?kg?mol^?1 were measured in water?Cdimethyl sulfoxide solutions at temperatures from (298.15 to 318.15)?K. The expansion factors of the polymer chains were calculated from the intrinsic viscosity data. The thermodynamic parameters (entropy of dilution parameter, the heat of dilution parameter, theta temperature, polymer?Csolvent interaction parameter and second osmotic virial coefficient) were derived by the temperature dependence of the polymer chain expansion factor. The thermodynamic parameters indicate that mixtures of water/dimethyl sulfoxide become poorer solvents for poly(vinyl pyrrolidone) as the temperature is increased. Also, the thermodynamic parameters indicate that water/dimethyl sulfoxide mixtures become better solvents for poly(vinyl pyrrolidone) by increasing the volume fractions of dimethyl sulfoxide.     

Semi‐interpenetrating polymer networks based on crosslinked poly(N‐isopropyl acrylamide) and methylcellulose prepared by frontal polymerization

In this work, semi‐interpenetrating gels of poly(N‐isopropyl acrylamide) and methylcellulose were successfully synthesized by using the Frontal Polymerization (FP) technique. The gels were obtained in the presence of dimethyl sulfoxide and trihexyltetradecylphosphonium persulfate, as polymerization solvent and radical initiator, respectively, hence avoiding the formation of bubbles during polymerization. Then, some of the gels containing dimethyl sulfoxide were thoroughly washed with water, hence obtaining the corresponding hydrogels. The effects of the ratio between poly(N‐isopropyl acrylamide) and methylcellulose, the amount of crosslinker and solvent medium (i.e., dimethyl sulfoxide and water) were thoroughly studied, assessing the influence of temperature and velocity of FP fronts on the glass transition temperature values (dried samples), on the swelling behavior and on the dynamic‐mechanical properties (gels swollen both in water and dimethyl sulfoxide). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 437–443     

Poly(phenylacetylene)s bearing a peptide pendant: helical conformational changes of the polymer backbone stimulated by the pendant conformational change

Optically active, cis-transoid poly(phenylacetylene) derivatives bearing a poly(gamma-benzyl-L-glutamate) [poly(PBGAm)] or poly(L-glutamic acid) [poly(PGAm)] chain as the pendant were prepared by polymerisation of the corresponding macromonomer with a rhodium catalyst followed by hydrolysis of the pendant ester groups. Their conformational changes in solution, induced by a helix-coil transition of the pendant polypeptides, were investigated using circular dichroism (CD) and absorption spectroscopies. A series of macromonomers with a different peptide chain lengths was synthesised by the polymerisation of the N-carboxyanhydride of gamma-benzyl-L-glutamate with a phenylacetylene bearing an alanine residue as the initiator. The obtained macromonomers (PBGAm) were further polymerised with a rhodium catalyst in N,N-dimethylformamide (DMF) to yield novel poly(phenylacetylene)s [poly(PBGAm)] with a poly(gamma-benzyl-L-glutamate) pendant. The poly(PBGAm) exhibited an induced circular dichroism (ICD) in the UV/Vis region of the polymer backbone in dimethyl sulfoxide (DMSO), probably due to the prevailing one-handed helix formation. The Cotton effect signs of a DMSO solution of the poly(PBGAm) were inverted and accompanied by a visible colour change in the presence of an increasing amount of chloroform or DMF containing lithium chloride. The results suggest that poly(PBGAm) may undergo a conformational change such as a helix-helix transition with a different helical pitch responding to a change in the alpha-helix content of the poly(gamma-benzyl-L-glutamate) pendant. Moreover, a water-soluble poly(PGAm) also showed a similar, but dramatic change in its helical conformation with a visible colour change stimulated by a helix-coil transition of the pendant poly(L-glutamic acid) chains by changing the pH in water.     

Adsorption Studies of Copper Sulfate on Hydrogels of Poly(Amido-Amines)

Abstract

The interaction between the active groups of polymeric gels of poly(amido-amines) such as poly(acrylamide-diallyldiethyl ammonium chloride) “cationic gel p(AM-DADEAmCl)” and poly(acrylamide-sodium acrylate-diallyldiethyl ammonium chloride) “amphoteric gel p(AM-AANa-DADEAmCl” with copper sulfate have been carried out by using polymeric gels of different swelling degree and different amine percent.

The capacity toward cations decreases with increasing the amine percent and the swelling degree but the capacity toward anions such as (SO₄₎ ^2- decreases with increasing swelling degree and increases with increasing the amine percent. These polymeric gels interact with copper sulfate at pH value >5 to form a crosslinked structures. Spectroscopic studies showed that the mechanism of crosslinking formation is a bond formation between the active group of polymeric chains and copper sulfate. The bond formation depends on the nature of the polymer chain. It was also found that the amide groups form complexes with hydrated cations, while both carboxylate and ammonium groups interact by ion-exchange mechanisms.     

Thermal decomposition of microbial poly(γ-glutamic acid) and poly(γ-glutamate)s

The thermal decomposition of poly(γ-glutamic acid), poly(α-methyl γ-glutamate) and ionic complexes of the polyacid with alkyltrimethyl ammonium salts was studied by TGA, GPC, and FTIR and NMR spectroscopies. It was found that both poly(γ-glutamic acid) and poly(α-methyl γ-glutamate) depolymerised above 200 °C by unzipping mechanism with generation of pyroglutamic acid and methyl pyroglutamate, respectively. On the other hand, the ionic complexes degraded through a two-stage process, the first stage being cyclodepolymerisation of the poly(γ-glutamate) main chain along with decomposition of the ionic complex promoted by the adsorbed water. Decomposition of the previously generated alkyltrimethyl ammonium compound followed by unspecific cracking of the resulting nitrogenated compounds accounted for the second degradation step, at higher temperatures. Mechanisms explaining the decomposition of the three studied systems were proposed according to collected data.     

Poly(ionic liquid)s as phase-transporter for graphene oxide liquid crystals from aqueous to non-polar organic phase via noncovalent functionalization

We synthesise a novel poly(ionic liquid) (PIL) and develop a procedure that allows the phase transfer of graphene oxides (GO) from water to organic solvent, retaining graphene oxide liquid crystal (GOLC) phase in various organic solvents, especially non-polar organic solvents. PIL ([PEP-MIM]DBS) is exploited in this procedure as a noncovalent functional material that is capable of transporting GO from aqueous to non-polar organic phase. PILs can decorate GO noncovalently and keep GO nano-sheets exfoliated in solid-state PILs/GO hybrids, which can well redisperse in organic solvents without any agglomeration. This expands the number of known solvents which can support GOLC phase to dimethyl formamide, dimethyl sulfoxide, acetonitrile, tetrahydrofuran, and a number of other non-polar organic solvents, many of which were not known to afford GOLC phase prior to this report, such as dichloromethane, tetrachloromethane, dichloroethane and tetrachloroethane.     

Metal ion promoted hydrogels for bovine serum albumin adsorption: Cu(II) and Co(II) chelated poly[(N-vinylimidazole)-maleic acid

Poly[(N-vinylimidazole)-maleic acid] (poly(VIm-MA)), copolymeric hydrogels were prepared by gamma-irradiating ternary mixtures of N-vinylimidazole-maleic acid-water in a (60)Co-gamma source. Cu(II) and Co(II) ions were chelated within the gels at pH=5.0. The maximum adsorption capacity of the gels were 3.71 mmol/g dry gel for Cu(II) and 1.25 mmol/g dry gel for Co(II) at pH=5.0. The swelling ratios of the gels were 1200% for poly(VIm-MA), 60 and 45% for Cu(II) and Co(II)-chelated poly(VIm-MA) gels at pH=5.0 in acetate buffer solution. These affinity gels with different swelling ratios for plain poly(VIm-MA), Cu(II)-, and Co(II)-chelated poly(VIm-MA), in acetate and phosphate buffers were used in the bovine serum albumin (BSA) adsorption/desorption studies in batch reactor. The maximum BSA adsorption capacities of the gels were 0.38 g/g dry gel for plain, 0.88 g/g dry gel for Cu(II)-chelated poly(VIm-MA) and 1.05 g/g dry gel for Co(II)-chelated poly(VIm-MA) gels. Adsorption capacity of BSA by the gels was reduced dramatically by increasing the ionic strength adjusted with NaCl. More than 95% of BSA were desorbed in 10 h in desorption medium containing 0.1M of EDTA for metal ion-chelated gels at pH=4.7.     

Intercalated Poly (2-acrylamido-2-methyl-1-propanesulfonic Acid) into Sulfonated Poly (1,4-phenylene ether-ether-sulfone) Based Proton Exchange Membrane: Improved Ionic Conductivity

A series of hybrid proton exchange membranes were synthesized via in situ polymerization of poly (2-acrylamido-2-methyl-1-propanesulfonic acid) PMPS with sulfonated poly (1,4-phenylene ether-ether-sulfone) (SPEES). The insertion of poly (2-acrylamido-2-methyl-1-propanesulfonic acid) PMPS, between the rigid skeleton of SPEES plays a reinforcing role to enhance the ionic conductivity. The synthesized polymer was chemically characterized by fourier-transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance ¹H NMR spectroscopy to demonstrate the successful grafting of PMPS with the pendent polymer chain of SPEES. A variety of physicochemical properties were also investigated such as ion exchange capacity (IEC), proton conductivity, water uptake and swelling ratio to characterize the suitability of the formed polymer for various electrochemical applications. SP-PMPS-03, having the highest concentration of all PMPS, shows excellent proton conductivity of 0.089 S cm⁻¹ at 80 °C which is much higher than SPEES which is ~0.049 S cm⁻¹. Optimum water uptake and swelling ratio with high conductivity is mainly attributed to a less ordered arrangement polymer chain with high density of the functional group to facilitate ionic transport. The residual weight was 93.35, 92.44 and 89.56%, for SP-PMPS-01, 02 and 03, respectively, in tests with Fenton’s reagent after 24 h. In support of all above properties a good chemical and thermal stability was also achieved by SP-PMPS-03, owing to the durability for electrochemical application.     

pH敏感性两亲聚合物网络PAA—l—PTHF的研究

以具有良好柔性和生物相容性的聚四氢呋喃（ＰＴＨＦ）为疏水链段,具有ｐＨ敏感性的聚丙烯酸（ＰＡＡ）为亲水链段,通过ＰＴＨＦ双端基大分子单体与丙烯酸自由基共聚,首次合成了聚丙烯酸－ｌ－聚四氢呋喃（ＰＡＡ－ｌ－ＰＴＨＦ）两亲聚合物网络,并对网络的结构、组成以及交联点密度进行了表征。两亲聚合物网络溶胀行为研究表明,ＰＡＡ－ｌ－ＰＴＨＦ既能在水中溶胀又能在有机溶剂中溶胀,在水中的溶胀度随网络亲水链段ＰＡＡ含     

Poly-Sugar: Modification of Poly(vinyl Alcohol)

This paper describes the attachment of sugar (sucrose) onto low molecular weight poly(vinyl alcohols) (etherification) to produce a new class of synthetic sweetener. Because of its regulated molecular weight, the new sweetener would pass through the digestive tract and be excreted in its original molecular form. We have termed the new class of sweeteners poly-sugar. The etherification of sucrose with poly(vinyl alcohol) can be carried out either in dimethyl sulfoxide or water. We have prepared poly-sugars with varying degrees of etherification (3.4–5.4). Highly etherified products were bitter, but a poly-sugar with a 4.23 degree of etherification was sweet without any bitter aftertaste.