Tb(III)与PNIPAM接枝核壳纳米微球相互作用的研究

利用透射电镜、X射线光电子能谱、动态激光光散射和荧光光谱技术对Tb(III)与聚N-异丙基丙烯酰胺(PNIPAM)接枝核壳纳米微球PNIPAM-g-P(NIPAM-co-St) (PNNS)的相互作用进行了研究. 结果表明: Tb(III)和热敏性的核壳纳米微球PNNS有显著的相互作用. 其一, Tb(III)可与PNNS中酰胺基团上的氧原子配位形成微球配合物Tb(III)-PNNS; 其二, Tb(III)-PNNS微球配合物兼具热敏性; 其三, 该配合物在545 nm处的荧光强度较Tb(III)增大了233倍, Tb(III)与PNNS分子间能量传递达到50%, 当Tb(III) 质量分数为12%时荧光强度最大.     

Tb(Ⅲ)与PNIPAM接枝核壳纳米微球相互作用的研究

利用透射电镜、X射线光电子能谱、动态激光光散射和荧光光谱技术对Tb(Ⅲ)与聚N-异丙基丙烯酰胺(PNIPAM)接枝核壳纳米微球PNIPAM-g-P(NIPAM-co-St)(PNNS)的相互作用进行了研究.结果表明:Tb(Ⅲ)和热敏性的核壳纳米微球PNNS有显著的相互作用.其一,Tb(Ⅲ)可与PNNS中酰胺基团上的氧原子配位形成微球配合物Tb(Ⅲ)-PNNS;其二,Tb(Ⅲ)-PNNS微球配合物兼具热敏性;其三,该配合物在545 nm处的荧光强度较Tb(Ⅲ)增大了233倍,Tb(Ⅲ)与PNNS分子间能量传递达到50%,当Tb(Ⅲ)质量分数为12%时荧光强度最大.     

聚N-异丙基丙烯酰胺-丙烯酸共聚微凝胶与Tb(Ⅲ)相互作用的研究

聚N-异丙基丙烯酰胺(PNIPAM)微凝胶是一类具有独特的温度响应性,即具有最低临界溶解温度(LCST)的高分子化合物,由于具有了LCST性能,当PNIPAM微凝胶受热时,在较窄的温度范围内,溶胀于微凝胶内的溶剂被挤出,从而导致微凝胶的粒子尺寸、粒子形态、亲水性、胶体稳定性以及微凝胶分散液的粘度、电泳流动性发生较大改变的现象。     

Mn~(2 )对聚N鄄异丙基丙烯酰胺的性能影响

合成了聚N鄄异丙基丙烯酰胺(PNIPAM)与Mn2 的配合物,并用荧光光谱、UV鄄Vis、FTIR、XPS进行了初步表征。说明Mn2 与PNIPAM侧链羰基氧或亚氨基氮原子发生了配位作用。由于Mn2 的发射光谱与PNIPAM激发光谱部分重叠以及Mn2 位于561nm的发射峰在Mn2 鄄PNIPAM体系发射光谱中消失,说明发生了较好的F觟rster能量传递。因此,在307nm紫外区荧光强度比PNIPAM增强了314%,使该配合物表现出较好的抑菌效果,而此时少量Mn2 对其低临界溶解温度(LCST)影响不大。     

Mn2+对聚N-异丙基丙烯酰胺的性能影响

合成了聚N-异丙基丙烯酰胺(PNIPAM)与Mn²⁺的配合物，并用荧光光谱、UV-Vis、FTIR、XPS进行了初步表征。说明Mn²⁺与PNIPAM侧链羰基氧或亚氨基氮原子发生了配位作用。由于Mn²⁺的发射光谱与PNIPAM激发光谱部分重叠以及Mn²⁺位于561 nm的发射峰在Mn²⁺-PNIPAM体系发射光谱中消失，说明发生了较好的F?rster能量传递。因此，在307 nm紫外区荧光强度比PNIPAM增强了314%，使该配合物表现出较好的抑菌效果，而此时少量Mn²⁺对其低临界溶解温度(LCST)影响不大。     

硫酸钠诱导单链聚(N-异丙基丙烯酰胺)相变的单分子力谱研究

聚（N-异丙基丙烯酰胺） （PNIPAM）具有独特的相变行为,已成为人们研究蛋白质折叠等生命过程发生机理的模型体系. 我们利用基于原子力显微镜（AFM）的单分子力谱技术（SMFS）研究了单链PNIPAM在硫酸钠诱导下的相转变过程,并定量化了相变后所形成塌缩结构的稳定性. 通过对单链PNIPAM的单分子力谱实验得知：在相变前,得到单调上升的力曲线,对应着PNIPAM无规线团结构的形变过程;相变后,得到的锯齿型力曲线,对应着PNIPAM塌缩结构在外力诱导下的解折叠过程. 首次从单分子水平观察到在外加盐的作用下,单链PNIPAM低温相转变和高温相转变的差异：相比于低温相转变,高温相转变生成的塌缩结构更加稳定.     

聚-N-异丙基丙烯酰胺的制备及应用进展

聚(N-异丙基丙烯酰胺)(PNIPAM)是一种温敏性高分子聚合物,在最低临界溶解温度(LCST)处会发生构象转变。对PNIPAM加以改性,可拓宽温敏性聚合物材料的研究领域,使其在药物负载运输、基因传递、化学分析和表面浸润性等领域发挥更大的应用价值。本文对PNIPAM的活性自由基聚合方法及其应用进展进行了综述,并展望了其发展前景。     

无机-高分子-无机多组分核壳纳米复合材料的制备和表征

Fe₃O₄ nanoparticles were prepared by chemical co-precipitation using palmitic acid as surfactant， then a uniformly dispersed system of Fe₃O₄@Polymethylmethacrylates(PMMA) core-shell structure was obtained. Furtherm-ore， polymethylmethacrylates(PNIPAM) was encapsulated on the surface of the Fe₃O₄@PMMA core-shell nano-structure to get Fe₃O₄@PMMA@PNIPAM double shell-core composite structure. After that， the Ag nano-particles were assembled on the surface of Fe₃O₄@PMMA@PNIPAM taking advantage of coordination reaction between Ag⁺ and nitrogen atom on the amide group of PNIPAM. The magnetism of composites is convenient for the catalyst separation from the solution.     

P(St-NIPAm)核-壳纳米粒子的制备及其光子晶体薄膜

以过硫酸铵为引发剂,固定反应单体物质的量之比,采用一步无皂乳液聚合法,制备粒径不同的聚(苯乙烯-N-异丙基丙烯酰胺)纳米粒子,研究了反应单体用量对纳米粒子粒径的影响;然后利用简单的垂直沉积法,在载玻片上自组装光子晶体薄膜。结果表明:制备的纳米粒子具有较高的单分散性并呈明显的核-壳结构,其粒径与反应单体用量呈线性关系;薄膜中纳米粒子呈面心立方紧密堆积,薄膜厚度约8μm;薄膜光子禁带的实验测量值与理论计算值基本一致,且禁带与纳米粒子粒径呈线性关系;当反应单体的总物质的量分别为20,25,30,35mmol时,自组装成的光子晶体薄膜的颜色分别呈蓝紫、蓝绿、黄绿和橘红色。     

Mn2+对聚N-异丙基丙烯酰胺的性能影响

合成了聚N-异丙基丙烯酰胺(PNIPAM)与Mn2+的配合物,并用荧光光谱、UV-Vis、FTIR、XPS进行了初步表征.说明Mn2+与PNIPAM侧链羰基氧或亚氨基氮原子发生了配位作用.由于Mn2+的发射光谱与PNIPAM激发光谱部分重叠以及Mn2+位于561nm的发射峰在Mn2+-PNIPAM体系发射光谱中消失,说明发生了较好的Forster能量传递.因此,在307 nm紫外区荧光强度比PNIPAM增强了314%,使该配合物表现出较好的抑菌效果,而此时少量Mn2+对其低临界溶解温度(LCST)影响不大.     

Study on interaction between Tb(III) and poly(N-isopropylacrylamide)

A new kind of the thermo-sensitive and fluorescent complex of poly(N-isopropylacrylamide) (PNIPAM) and Tb(III) was synthesized by free radical polymerization, in which PNIPAM was used as a polymer ligand. The complex was characterized by using X-ray photoelectron spectroscopy (XPS), ultraviolet-visual (UV), Fourier transform infrared (FT-IR) and fluorescence spectroscopy. The results from the experiments indicated that there is a strong interaction between PNIPAM and Tb(III), leading to a decrease in the electron density of nitrogen and oxygen atoms and an increase in the electron density of Tb(III) in the PNIPAM containing Tb(III) by contrast with PNIPAM and Tb(III), respectively, meanwhile, exhibiting that the Tb(III) is mainly bonded to oxygen atoms in the polymer chain of PNIPAM and formed the complex of PNIPAM-Tb(III). After forming the PNIPAM-Tb(III) complex, the emission fluorescence intensity of Tb(III) in the PNIPAM-Tb(III) complex is significantly enhanced because the effective intramolecular energy transfer from PNIPAM to Tb(III). Especially, the emission intensity of the fluorescence peak at 547 nm can be increased as high as 145 times comparing with that of the pure Tb(III). The intramolecular energy transfer efficiency for fluorescence peak at 547 nm can reach as high as 68%. The fluorescence intensity is related the weight ratio of Tb(III) and PNIPAM in the PNIPAM-Tb(III) complex. When the weight ratio is 1.4%, the maximum fluorescence enhancement can be obtained. Nevertheless, the lower critical solution temperature of PNIPAM containing a low content of Tb(III) has not obviously changed after the formation of the complex of PNIPAM-Tb(III) by the interaction between PNIPAM and Tb(III). This novel thermosensitive and fluorescence characterization of the PNIPAM-Tb(III) complex may be useful in the fluorescence systems and the biomedical field.     

Tb(III)‐modified properties of thermosensitive core–shell microspheres

A novel functional complex with the thermosensitive, magnetic, and fluorescent properties of poly(N‐isopropylacrylamide)‐grafted poly(N‐isopropylacrylamide‐co‐styrene) (PNNS) microspheres and Tb(III), PNNS–Tb(III), has been synthesized and characterized with different techniques. When PNNS with a core–shell structure interacts with Tb(III), Tb(III) mainly bonds to oxygen of the carbonyl groups of PNNS, forming the novel PNNS–Tb(III) complex. PNNS shows antiferromagnetic behavior, whereas the PNNS–Tb(III) complex exhibits paramagnetic behavior. The saturation magnetization is approximately 50 times higher than that of PNNS. The fluorescence intensity of the PNNS–Tb(III)complex at 545 nm is enhanced as much as 223 times in comparison with that of pure Tb(III). The novel magnetic and fluorescent properties of the PNNS–Tb(III) complex may be useful in biomedicine and fluorescence systems. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3121–3127, 2006     

Study on interaction between Tb(III) and poly(N-isopropylacrylamide)-g-poly(N-isopropylacrylamide-co-styrene) core-shell nanoparticles

Based on the synthesis of poly(N-isopropylacrylamide-co-styrene) P(NIPAM-co-St) and poly(N-isopropylacrylamide) (PNIPAM) grafted P(NIPAM-co-St) core-shell nanoparticle, a new kind of thermoresponsive and fluorescent complex of Tb(III) and PNIPAM-g-P(NIPAM-co-St) (PNNS) was successfully prepared. The PNNS-Tb(III) complex was characterized with the different techniques. It was found that when PNNS with the core-shell structure interact with Tb(III), Tb(III) mainly bonded to O of the carbonyl groups of PNNS, forming the novel PNNS-Tb(III) complex. After forming the complex, the emission fluorescence intensity of Tb(III) in the complex is significantly enhanced. Especially, the maximum emission intensity of the PNNS-Tb(III) complex at 545 nm is enhanced about 223 times comparing to that of the pure Tb(III) because the effective intramolecular energy transfer from PNNS to Tb(III). The intramolecular energy transfer efficiency from PNNS to Tb(III) reaches 50%. The fluorescence intensity is related the weight ratio of Tb(III) and PNNS in the PNNS-Tb(III) complex. When the weight ratio of Tb(III) and the PNNS is 12 wt%, the enhancement of the emission fluorescence intensity at 545 nm is highest. This novel fluorescence characterization of the PNNS-Tb(III) complex may be useful in the fluorescence systems and the biomedical field.     

Synthesis and characterization of thermally reversible macroporous poly(N-isopropylacrylamide) hydrogels

Macroporous hydrogels are characterized by large pore sizes, high pore volumes, and high specific surface area. Besides these characteristics, macroporous hydrogels based on thermally reversible polymers respond to temperature changes much faster than hydrogels prepared by a conventional method. Crosslinked poly(N-isopropylacrylamide) (polyNIPAAm) forms a thermally reversible hydrogel which shows a lower critical solution temperature (LCST) ca. 33°C in aqueous solutions. We have synthesized thermally reversible polyNIPAAm hydrogels having macroporous structures by a new method. These macroporous hydrogels have large pore volumes, large average pore sizes, and faster macromolecule permeation rates in comparison to conventional polyNIPAAm hydrogels synthesized by a conventional method. Compared with conventional polyNIPAAm hydrogels, the macroporous polyNIPAAm hydrogels have higher swelling ratios at temperatures below the LCST and exhibit faster deswelling and reswelling rates. The deswelling rates are especially rapid. These thermally reversible macroporous hydrogels may be very useful in controlled active agent delivery and toxin removal, as well as dewatering of solutions. Peptides or proteins may behave as if they were in bulk solution within the large aqueous pores, and this may reduce their inactivation when such gels are used for their storage and later release. The gels may also be useful in microrobotic devices due to their fast response to temperature. © 1992 John Wiley & Sons, Inc.     

乙基纤维素接枝聚N-异丙基丙烯酰胺共聚物合成及其胶束化研究

通过单电子转移“活性”/可控自由基聚合的方法制备了具有双亲性及温度响应性的乙基纤维素接枝聚N-异丙基丙烯酰胺共聚物(EC-g-PNIPAm). 通过凝胶渗透色谱、核磁氢谱和红外光谱等对合成的接枝共聚物进行了表征. 我们发现此反应在混合溶剂四氢呋喃/甲醇的混合溶剂中是活性可控的. EC-g-PNIPAm接枝共聚物能够在选择性溶剂水中发生自组装现象, 形成稳定的以乙基纤维素为核、聚N-异丙基丙烯酰胺为壳的球形胶束. 并且随着温度的升高, 支链聚N-异丙基丙烯酰胺发生塌缩使得球形胶束发生收缩.     

PNIPA和PDEA在水-甲醇混合溶剂中性质的研究

分别研究了聚N-异丙基丙烯酰胺（PNIPA）和聚N,N-二乙基丙烯酰胺（PDEA）在水-甲醇混合溶剂中的溶液性质.结果表明,在PDEA和PNIPA体系中均存在水和甲醇分子之间的复合.由于PDEA比PNIPA的亲脂性强,在水-甲醇混合溶剂中,水与甲醇分子形成的复合物对PDEA和PNIPA的溶剂化作用不同,导致随着体系中甲醇体积分数（φ）的增大,PNIPA体系的低临界溶解温度（TLCS）发生了再进入相转变,而PDEA体系的TLCS则逐渐升高.     

The sol-gel approach towards thermo-responsive poly(N-isopropyl acrylamide) hydrogels with improved mechanical properties

A new type of thermo-responsive hydrogels based on the polymer poly(N-isopropyl acrylamide) (PNIPAA) has been synthesized with the sol-gel technology. For the preparation of this type of nano-structured hydrogels, the inorganic silica phase was synthesized by the sol-gel process in the presence of an aqueous solution of high molecular weight PNIPAA. This combination of the organic and inorganic phases forms hybrid hydrogels with a semi-IPN morphology. The unique structure of these hydrogels improves the mechanical stability to a great extent as compared to conventional PNIPAA-hydrogels. This was shown by stress-strain experiments and the capability to absorb and desorb large amounts of water. The silica only slightly influences the transition temperature of the hydrogels but allows us to vary the thermo-responsive properties of the materials to a great extent.     

Interaction of Ionic Surfactants with a Hydrophobic Modified Thermosensitive Polymer

The interactions of a hydrophobic modified thermosensitive polymer poly(N-isopropylacrylamide)-ran-poly(methacrylic acid)-ran-poly(octadecyl acrylate) with five ionic surfactants, namely, sodium dodecyl sulfate (SDS), dodecayltrimethylaminium bromide (DTAB), 1,2-bis(dodecyldimethylammonio)- hexane dibromide (12-6-12), 1-dodecanaminium, N,N′-[(1,4-dioxo-1,4-butanediyl) bis(oxy-2,1-ethanediyl)] bis[N,N-dimethyl-, bromide] (12-su-12), and dodecanaminium, N, N′-[[(2E)-1,4-dioxo-2-butene-1, 4-diyl]bis(o-xy-2,1ethanediy-l)] bis[N,N-dimethyl-, bromide] (12-fo-12) were investigated by the static-steady fluorescence methods using crystal violet and pyrene as the probes. It was found that the SDS interacted with the polymer driven by the hydrophobic interaction, while the cationic surfactants first entered the core of the polymer micelle through the hydrophobic interaction then the corona area of the polymer micelle through the hydrophobic and static electrical interactions. Measurements of the transmittances of the polymer/surfactants/PBS mixtures at different temperatures showed that the SDS suppressed the phase transition of the system, while additions of the cationic surfactants into the polymer induced the phase transitions of the polymer complex systems first, then suppressed them after the minimum values of the lower critical phase transition temperatures (LPTT) was reached. It was also found that increase of the MAA content in the polymer could broaden the LPTT range adjusted by the cationic surfactants.