二步法制备CO2响应性DAAM-co-VAm温敏共聚物及其在水溶液中的相变行为

以双丙酮丙烯酰胺（DAAM）和N-乙烯基甲酰胺（NVF）为单体，以过硫酸铵和亚硫酸氢钠为引发剂进行水溶液自由基聚合，合成了共聚物P(DAAM-co-NVF)，并在碱性条件下水解制得了聚合物P(DAAM-co-VAm)。采用傅立叶红外光谱（FTIR）、核磁共振氢谱（1H-NMR）、凝胶渗透色谱（GPC）和热失重分析（TGA）对合成的产物进行了表征分析，同时以紫外可见光谱（UV-Vis）和差示扫描量热仪（DSC）对P(DAAM-co-NVF)和P(DAAM-co-VAm)水溶液的相转变行为进行了研究。结果表明，所制备的聚合物P(DAAM-co-NVF)和P(DAAM-co-VAm)具有可调控的低临界溶解温度（LCST），通过改变组成和聚合物溶液的浓度，可以调控P(DAAM-co-NVF)和P(DAAM-co-VAm)的LCST。而且，在P(DAAM-co-VAm)水溶液中通入CO2可以调控聚合物的LCST。P(DAAM-co-VAm)水溶液的LCST具有可逆的CO2/N2开关响应性能。     

pH、温度和光三重敏感的PDMAEMA-AZO的研究

在含偶氮苯的三硫酯链转移剂（CTA-AZO）存在下，将甲基丙烯酸二甲氨基乙酯（DMAEMA）通过可逆加成断裂链转移（RAFT）聚合，制备了pH、温度和光三重敏感的含偶氮苯端基的聚甲基丙烯酸二甲氨基乙酯聚合物（PDMAEMA-AZO）。采用紫外光谱（UV）、红外光谱（FTIR）、核磁共振氢谱（1HNMR）和凝胶渗透色谱（GPC）对PDMAEMA-AZO的结构进行了表征，并考察了聚合物的光敏性、温敏性和pH敏感性。GPC结果表明，PDMAEMA-AZO的相对分子质量可控，且相对分子质量分布（PDI）小于1.78。PDMAEMA-AZO在不同溶剂中（氯仿、乙醇和水）的光敏性实验结果显示，该聚合物在氯仿、乙醇和水中均能够快速进行可逆光致顺反异构反应，在紫外与可见光的交替照射下，快速达到光稳态。PDMAEMA-AZO的温敏性实验表明，与聚甲基丙烯酸二甲氨基乙酯（PDMAEMA）相比，PDMAEMA-AZO的低临界溶解温度（LCST）更低。随着聚合物浓度的增加，其LCST降低，且相变窗口变窄。当pH超过9.44时，该聚合物的LCST保持不变，pH由9.44下降到7.34时，LCST升高，pH＜7.34时不再具有温敏性，说明该类聚合物是一种pH控制的具备LCST的温敏性聚合物。在紫外与可见光交替照射下，PDMAEMA-AZO 的LCST 表现为可逆的升高和降低，表明聚合物PDMAEMA-AZO具备光控温敏性。     

NIR光响应型PNIPAM/GO复合体系的制备及药物释放

多刺激合作响应的智能药物输送体系具有重要的研究价值。采用乳液聚合法将N-异丙基丙烯酰胺（NIPAM）与丙烯酸（AA）聚合为PNIPAM-co-AA微凝胶，并进一步与氧化石墨烯（GO）超声共混得到PNIPAM-co-AA/GO复合体系，将其应用于药物释放研究。采用FTIR、TEM、DLS、UV-Vis对微凝胶及复合体系的结构和性能进行表征。结果表明，PNIPAM-co-AA微凝胶的粒径约为458.7 nm，最低临界相转变温度（LCST）为40 ℃，具有温度敏感性和pH敏感性。在PNIPAM-co-AA微凝胶体系中引入GO后， GO的存在将复合体系的温度响应控制转化成了近红外（NIR）响应，结果表明，复合体系受到NIR光照射，可在3 min内将NIR光能转化为热能达到微凝胶的LCST，多次循环后光热转化性能稳定。药物释放实验结果表明，有NIR、pH 7.4条件下，5-氟尿嘧啶（5-FU）在24 h内的累积释放率最高为77.24%。     

(p-CMS)-g-DMAEMA两亲性环境敏感高聚物的合成及其控制释放研究

应用大分子引发剂,以原子转移自由基聚合技术（ATRP）舍成了聚对氯甲基苯乙烯接枝聚甲基丙烯酸N,N-二甲基氨基乙酯[（p-CMS）-g-DMAEMA]的两亲性环境敏感梳状高聚物。IR分析表明所得高聚物与设计结构基本一致;以特性黏数表征了高聚物的相对分子质量;粒度分析表明,高聚物具有明显的温度与pH值敏感性;在低临界溶解温度（LCST）下,水溶液中高聚物胶束数均粒径约30～50nm;在不同pH值环境中,通过调节亲水基团与疏水基团的比例,可在18～56℃范围内调节LCST,pH〈7．5时LCST消失。DSC分析表明梳状共聚物具有明显的微相分离结构。对非诺夫他林的控制释放实验表明高聚物具有较好地控制释放性能。     

侧链含芘基的聚N-异丙基丙烯酰胺的合成及性能

将N-异丙基丙烯酰胺（NIPAM）和甲基丙烯酸-β-(1-芘丁酰氧基)乙酯（PyBEMA）通过自由基溶液共聚合成了侧链含芘基的聚N-异丙基丙烯酰胺共聚物，并采用红外光谱、紫外光谱、核磁共振氢谱对共聚物进行了结构表征。研究了不同投料比对共聚物收率、组成和相对分子质量及其分布的影响。共聚物水溶液温敏性研究表明，共聚物是一类具有低临界溶解温度（LCST）温敏性聚合物，随着共聚物中的芘基含量的升高，其LCST下降；加入α-环糊精（α-CD）会引起共聚物LCST略微升高，而加入β-CD和γ-CD，会导致LCST降低，而且γ-CD引起LCST的降低更显著。共聚物水溶液荧光性能研究表明，共聚物在水中有轻微的疏水聚集，出现侧链芘基激基缔合物荧光。室温下，加入β-CD能够降低共聚物侧链芘基之间的疏水聚集。随着温度的升高，芘基的荧光强度（IM）先下降，后突然升高，然后达到稳定并略微下降；而芘激基缔合物的荧光强度（IE）先出现略微升高，然后基本保持不变，接着缓慢下降。I1/I3荧光强度比值随着温度的升高呈现下降趋势，在聚合物发生相转变时的温度区间内迅速降低。     

沉淀聚合法制备VCL／NVP温敏型微凝胶及其性能研究

用沉淀聚合法,以N-乙烯基己内酰胺（VCL）和N-乙烯基吡咯烷酮（NVP）为共聚单体、N,N-亚甲基双丙烯酰胺（MBA）为交联剂,通过改变交联剂的量制备了-系列不同粒径的温敏型微凝胶。用纳米颗粒力度分析仪（DLS）和原子粒显微镜（AFM）对凝胶进行了表征。结果表明：粒子为球型单分散;在15—55℃范围内凝胶粒径随温度升高而减小,具有温度敏感性,最低临界转变温度（LCST）为35℃;交联剂的量不改变最低临界转变温度,只改变粒子大小。     

基于酶引发的温敏聚合物的合成与性能

以2-甲基-2-丙烯酸-2-（2-甲氧基乙氧基）乙酯（MEO2MA）和低聚乙二醇甲醚甲基丙烯酸酯（OEGMA500）为单体，利用辣根过氧化物酶（HRP）/乙酰丙酮（ACAC）/H2O2三元催化体系引发自由基聚合，合成了温敏无规共聚物P(MEO2MA-co-OEGMA500)。通过GPC、1HNMR、FTIR、DSC等对合成聚合物的数均分子量、分子量分布、结构及热性能进行了表征。通过测定聚合物溶液在不同温度下的透光率和粒径对聚合物的温敏性能进行了表征。制备了n(MEO2MA)∶n(OEGMA500)分别为100:0、95:5、93:7、90:5、85:15的温敏聚合物，结果表明，随着单体OEGMA500投料占比的增加，合成聚合物的LCST从24 ℃增加至39 ℃，聚合物玻璃化转变温度从-11.75 ℃逐渐降低至-14.74 ℃；LCST随聚合物水溶液浓度增加而降低；升高温度，聚合物平均粒径增加，比在低温条件下聚合物平均粒径大82.5~135.6 nm。     

聚(N-乙烯基己内酰胺)的合成及温度响应性能研究

用可逆加成-断裂链转移(RAFT)自由基聚合合成了分子量分布较窄的聚(N-乙烯基己内酰胺)(PNVCL),用红外光谱(FT-IR)、核磁共振氢谱(~1H NMR)和凝胶渗透色谱(GPC)对其结构进行了表征;用浊度法研究了无机盐、糖以及表面活性剂对PNVCL溶液低临界溶解温度(LCST)的影响。结果表明, NH_4Br、NaBr、NH_4Cl、NaCl使PNVCL溶液的LCST降低,但KI使PNVCL溶液的LCST升高,LCST降低或升高的程度主要取决于盐中阴离子的种类和离子浓度:糖的结构和浓度对PNVCL溶液的LCST有影响,十二烷基磺酸钠(SDS)则使PNVCL溶液的LCST升高。     

RAFT聚合制备温敏性含糖共聚物

采用酶促法合成了含糖单体6-O-乙烯基己二酸-D-吡喃型葡萄糖酯(OVAG),使用可逆加成链断裂转移自由基聚合法(RAFT聚合)将N-异丙基丙烯酰胺(NIPAAm)和OVAG共聚,制备分散度(PDI)低且具有温度敏感性的含糖高聚物Poly(NIPAAm-co-OVAG)。用1H NMR,傅里叶变换红外光谱（FTIR）,凝胶渗透色谱(GPC)对聚合物进行了表征。通过透射电子显微镜（TEM）发现自组装形成的聚合物胶束结构规整且粒径均匀。通过紫外-可见光谱对聚合物温敏性检查表明,共聚物的低临界溶解温度(LCST)可以通过共聚单体的比例进行调控。当NIPAAm与OVAG的物质的量之比为14:1时,共聚物的LCST值为36 oC,在人体温度下可以形成纳米胶束,在药物载体方面拥有广阔前景。     

链状流体的分子热力学模型(IV)高分子系统的液液平衡计算

将作者先前提出的链状流体混合物的分子热力学模型应用于高分子系统液液平衡的计算,对具有最高会溶温度（UCST)和最低会溶温度（LCST）的高分子共混物的液液平衡,采用两个相互作用参数可以取得令人满意的关联结果。对具有LCST的高分子溶液的液液平衡计算,需对高分子链长作适当调整。     

Fractionation and characterization of linear low-density polyethylene at a lower critical solution temperature (LCST)

The composition and molecular weight distribution of linear low-density polyethylenes (LLDPE) have been determined by fractionation and characterization at a lower critical solution temperature (LCST). The fractionation in 2,4-dimethyl pentane takes advantage of the fact that the LCST is sensitive to the side-group content as indicated by the 70 K difference between the LCSTs of PE and polypropylene at the same molecular weight (MW). Temperature-rising elution fractionation (TREF) and LCST fractions are compared by IR and SEC and also by a new method based on turbidity at an LCST. It is found that the LCST fractionation is sensitive to MW and TREF largely depends on a comonomer content. Calibration of the LCST method for MW distribution and effect of the nature of the comonomer on the LCST are discussed. The LCST technique associated with IR analysis is found to be quite effective for characterizing LLDPE.     

N-异丙基丙烯酰胺共聚物的温度敏感性研究

通过自由基聚合合成了 N-异丙基丙烯酰胺和甲基丙烯酸甲酯及甲基丙烯酸的共聚物。研究了甲基丙烯酸甲酯和甲基丙烯酸的加入对聚 N-异丙烯酰胺温度敏感性的影响 ,并考察了溶液中盐浓度和 p H对共聚物温度敏感性的影响     

Simultaneous multiple sample light scattering detection of LCST during copolymer synthesis

This work has two objectives in the investigation of polymer solution lower critical solution temperature (LCST): First, to develop a new instrument to monitor LCST onset during copolymer synthesis by coupling several thermostatted light scattering flow cells to the output stream of an ACOMP system (Automatic Continuous Online Monitoring of Polymerization reactions). Second, to use this to investigate effects on LCST when N-isopropylacrylamide (NIPAM) is copolymerized with a charged comonomer, styrene sulfonate (SS). This comonomer pair has widely separated reactivity ratios. SS is rapidly consumed, yielding composition drift toward NIPAM rich polymer. High content SS chains inhibited LCST, and SS was dramatically effective at suppressing LCST down to copolymers of 5% molar SS in 10 mM NaCl aqueous solvent. LCST for higher content SS chains was elevated and required significant additional ionic strength to occur. It was determined that the suppression of the LCST by SS is chiefly an intramolecular effect.     

Online,continuous monitoring of the sensitivity of the LCST of NIPAM-Am copolymers to discrete and broad composition distributions

The lower critical solution temperature (LCST) of NIPAM/Acrylamide copolymers was monitored during synthesis using second generation ACOMP (automatic continuous online monitoring of polymerization reactions) for a series of discrete starting compositions. A full sweep of NIPAM/Am compositions was subsequently obtained in a semi-batch feed of NIPAM into Am, allowing LCST behavior to be assessed over all compositions of the two copolymers. A separate Simultaneous Multiple Sample Light Scattering (SMSLS) instrument was used to assess compositional polydispersity via the broadening of the LCST temperature transition as compositional heterogeneity of samples increases. This was achieved by combining LCST data as a function of composition and added salt into a master equation. Extended period SMSLS monitoring of the aggregates formed when the LCST is reached showed they are reversible on the short time scale of hours, but are irreversible for homopolymer NIPAM with salt and for copolymers on the scale of days.     

Copolymers of N‐isopropylacrylamide,HEMA‐lactate and acrylic acid with time‐dependent lower critical solution temperature as a bioresorbable carrier

Copolymers of N‐isopropylacrylamide (NIPAAm), 2‐hydroxyethyl methacryl lactate (HEMA‐lactate) and acrylic acid (AAc) were prepared, with varying mole ratios of monomers, to develop a bioresorbable in‐situ‐gelling material with a time‐dependent lower critical solution temperature (LCST). The synthesized copolymers were characterized by nuclear magnetic resonance, gel permeation chromatography and differential scanning calorimetry. In 0.1 M phosphate‐buffered saline solution of pH 7.4, these copolymers had an LCST below body temperature. The LCST decreased as the HEMA‐lactate content of the copolymers was increased. Furthermore, in these conditions, the LCST of the copolymers exhibited time‐dependent properties, due to hydrolysis of the HEMA‐lactate. As the HEMA‐lactate hydrolyzed, the copolymers became more hydrophilic, thereby leading to an increase in LCST. This hydrophilicity caused copolymers of approximately 6 mol% of AAc to exhibit an LCST above body temperature after hydrolysis. In neutral solution, copolymers with varying mol% of AAc saw their LCST rise above 37 °C within one to ten days, depending upon the HEMA‐lactate/NIPAAm ratio, due to the complete hydrolysis of the HEMA‐lactate. The above properties indicate that these copolymers would be useful for drug delivery because their variable LCST makes them bioresorbable. Copyright © 2004 Society of Chemical Industry     

Deswelling characteristics of poly(N-isopropylacrylamide) hydrogel

Poly(N-isopropylacrylamide) gels exhibit a lower critical solution temperature (LCST) behavior in aqueous solution. At temperatures below the LCST, the gel is more hydrated than at temperatures above the LCST. At the LCST, the volume change is sharp. It is shown here that the water content of the gel above the LCST depends upon previous states of the gel (e.g., dry or wet), the heating rate, and the gel thickness. Deswelling kinetics are also affected by the gel thickness. Caffeine release experiments indicate that microscopic water pockets are formed within the matrix during the rapid gel collapse procedure. © 1994 John Wiley & Sons, Inc.     

温敏性萃取水凝胶对生物大分子的分离

合成了均聚的聚N 异丙基丙烯酰胺(PNIPAM)水凝胶以及N 异丙基丙烯酰胺与丙烯酰胺共聚的〔P(NIPAM-AM)〕水凝胶,并研究了它们的溶胀性能及其对生物大分子的萃取分离性能。结果表明,两种温敏凝胶具有很好的溶胀性能,其低临界共溶温度(LCST)分别为30 4和31 0℃,它们对蛋白质和酶的分离效率在LCST附近发生突跃,如PNIPAM水凝胶对白蛋白的分离效率在LCST前后从96 2%降至59 8%。当交联剂N,N 次甲基双丙烯酰胺(Bis)的质量分数w(Bis)>4%时,分离效率大于90%(LCST以下)。     

Synthesis and solution properties of temperature‐sensitive copolymers based on NIPAM

A kind of temperature‐sensitive water‐soluble polymers P(NIPAM‐HEMA‐AM) of N‐isopropylacrylamide (NIPAM), hydroxyethyl methacrylate (HEMA) and acrylamide (AM) were synthesized by free radical aqueous solution copolymerization. The polymers were characterized by Fourier transform infrared spectrum (FTIR) method. Solution properties, such as the influences of monomer ratios and additives on the low critical soluble temperature (LCST) of the polymer solutions as well as the viscosity‐temperature properties were studied. The results show that the polymer concentrations have no significant influence on the LCST of polymer solutions. The incorporation of HEMA units leads to a lower LCST, while AM units to a higher LCST. The additions of small molecules such as salt and surfactant also have significant effect on the LCST, the addition of NaCl decreases the LCST, while the addition of sodium dodecylbenzenesulfonate (SDBS) increases the LCST. The apparent viscosity of polymer solutions depends on temperature. The 1.5 wt % aqueous solutions of P(NIPAM‐HEMA‐AM) exhibits good thermo‐thickening behavior over 55°C, whereas the 0.8 wt % aqueous solutions do not show this behavior during the heating process. The aqueous solutions of P(NIPAM‐HEMA‐AM) are viscoelastic fluids, and the viscoelasticities mainly depend on temperature. Both the storage modulus (G') and loss modulus (G'') of 1.5 wt % polymer solutions increase with temperature. Over 55°C, G' exceeds G'', and the polymer solutions are elasticity‐dominated. In contrast, below 55°C, G'' is larger than G', and the polymer solutions are viscosity‐dominated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

温敏聚N-异丙基丙烯酰胺的载药和释药性能研究

以对乙酰氨基酚为模型药物分子,温敏水凝胶聚N-异丙基丙烯酰胺(PNIPAAm)为载体,研究了药物在凝胶上的负载和在不同温度(25和37℃)下磷酸盐缓冲溶液(pH 7.4)中的释放行为.结果表明,对乙酰氨基酚的负载量约为35wt％,并且与载体PNIPAAm存在氢键作用.药物在磷酸盐缓冲溶液中的体外模拟释放结果显示,当温度(37℃)高于凝胶的LCST时,对乙酰氨基酚释放的较慢;当温度(25℃)低于其LCST时,释放的较快.因此,可通过环境温度的改变达到APAP在载体PNIPAAm上控制释放的目的.     

Comprehensive Alcohol-/Ion-Responsive Properties of Poly(N-Isopropylacrylamide-co-Benzo-18-Crown-6-Acrylamide) Copolymers

abstract In this paper, we report on the comprehensive alcohol-/ion-responsive properties of a smart copolymer poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) (P(NIPAM-co-BCAm)). The orthogo...