聚(N-乙烯基己内酰胺)在二元水溶液中的温度响应性相变行为

用浊度法研究了聚(N-乙烯基己内酰胺)(PNVCL)在不同浓度的几种非质子溶剂如二甲基亚砜(DMSO)、N,N-二甲基甲酰胺(DMF)、四氢呋喃(THF)、1, 4-二氧六环和质子溶剂(几种低级醇)的水溶液中低临界溶液温度(LCST)的变化情况。结果表明:PNVCL的LCST随DMF、THF、1, 4-二氧六环和CH_3OH在其水溶液中浓度的增加而升高,其中DMF和1, 4-二氧六环对PNVCL的LCST的影响较大,其次是THF,而甲醇对其LCST的影响最小。乙醇、1-丙醇、2-丙醇在低浓度时导致PNVCL的LCST降低,随着浓度增加其LCST升高。与其他溶剂不同的是DMSO,PNVCL的LCST随DMSO在水溶液中浓度的增加先升高后下降。     

N-乙烯基己内酰胺和N-乙烯基咪唑及混合物的沉淀聚合

在不同溶剂采用沉淀聚合法制备了聚N-乙烯基己内酰胺PNVCL、聚N-乙烯基咪唑PNVI及其共聚物。实验发现,正己烷和环己烷适宜于PNVCL的沉淀均聚,甲苯适宜于PNVI的沉淀均聚,而两种单体共聚时,采用正己烷-甲苯混合溶剂可实现共聚物的沉淀聚合。考察了溶剂用量、引发剂AIBN用量、聚合温度、时间和搅拌对聚合物收率和温敏性的影响。采用分光光度计对温敏性进行了初步表征。结果表明,沉淀聚合得到的PNVCL具有最低临界溶液温度LCST,PNVI不具有LCST,共聚物的LCST突变不明显。     

N-乙烯基己内酰胺的活性/可控自由基聚合

聚(N-乙烯基己内酰胺)(PNVCL)是一种重要的温度响应性聚合物,其最低临界溶液温度(LCST)在生理温度范围内,而且PNVCL水解不会产生有毒的小分子胺,其单体价格便宜,因此PNVCL及其共聚物在生物医药领域具有潜在的应用价值和较好的工业化前景。活性/可控自由基聚合是合成PNVCL及其共聚物的重要手段。本文综述了N-乙烯基己内酰胺(NVCL)的原子转移自由基聚合(ATRP),可逆加成-断裂链转移(RAFT)聚合和有机钴调控自由基聚合(CMRP)的研究进展。对配体、溶剂、引发剂对NVCL的ATRP的影响进行了讨论。概述了黄原酸酯、二硫代酸酯、二硫代氨基甲酸酯、三硫代酸酯链转移剂调控的NVCL的RAFT聚合。对单体加入顺序对合成基于PNVCL的嵌段共聚物的影响和活性/可控自由基聚合在合成拓扑结构高分子中的应用进行了介绍。最后对NVCL的活性/可控自由基聚合的发展方向进行了展望。     

聚N-乙烯基己内酰胺及其共聚物的合成与应用

综述了聚N-乙烯基己内酰胺(PNVCL)及其共聚物的合成与用途研究现状,评述了不同聚合方法。指出了聚N-乙烯基己内酰胺系列聚合物在各个领域的应用前景及开发策略。     

聚(N-异丙基丙烯酰胺)类材料的应用

聚(N-异丙基丙烯酰胺)(PNIPAAm)及其共聚物,在水溶液中表现出最低临界溶液温度(LCST),在LCST附近会发生可逆相转变。利用这种特性,可将热敏性高分子材料应用于生物医学工程、免疫分析、催化、分离提纯等领域。主要综述了热敏性PNIPAAm类高分子材料,在这些领域中的应用情况。     

温敏型聚合物PNIPAAm辅助的溶菌酶体外复性

合成了 3种具有不同分子量的温敏型聚合物聚 (N 异丙基丙烯酰胺 ) (PNIPAAm) ,测定了其分子量分布以及相应的低临界溶解温度 (LCST) .在溶菌酶复性溶液中加入PNIPAAm可促进溶菌酶复性 ,其中采用中等分子量M—PNIPAAm(Mw 为 2 2× 10 4 g mol)时溶菌酶的复性效果最佳 ,并采用荧光发射光谱技术表征了PMIPAAm分子结构对于溶菌酶结构的影响 .系统考察了采用M—PNIPAAm时 ,复性液中尿素浓度、蛋白质浓度和温度等条件对溶菌酶复性效果影响 .结果显示尿素与M—PNIPAAm对于溶菌酶复性呈现协同效应 ,复性操作温度不仅同溶菌酶自身特性有关 ,而且还受到M—PNIPAAm自身性质变化的影响 .研究结果表明温敏型高聚物在高浓度蛋白质的大规模体外复性中具有很好的应用前景     

DTPA-PNIPAAm的合成及热敏性研究

热敏水溶性高分子聚(N-异丙基丙烯酰胺)(PNIPAAm)在水溶液中有最低临界溶液温度(LCST).当温度在LCST附近发生变化时,PNIPAAm可发生逆相转变.基于该特性,可通过PNIPAAm将放射性治疗核素运输到病变组织通过射线杀灭病变细胞.通过4,4′-偶氮二(氰戊酸)、乙二胺、二乙三胺五乙酸酐(DTPAA)、N-异丙基丙烯酰胺合成了带DTPA端基的PNIPAAm,合成的DTPA-PNIPAAm保持了与PNIPAAm相似的LCST.本文的工作为PNIPAAm运输金属治疗核素奠定了基础.     

温度/pH响应性MPEG-b-PCL/PNVCL-b-PCL共聚物复合胶束的制备及载药性质

以基于亚胺键的嵌段共聚物为构筑单元的温度/pH响应性共聚物复合胶束(CMs), 由于具有亚胺键和核-壳-冠结构, 表现出较高的灵敏度和稳定性. 以聚乙二醇单甲醚(MPEG)、 N-乙烯基己内酰胺(NVCL)和ε-己内酯(ε-CL)为原料, 分别制备了端醛基聚乙二醇单甲醚(MPEG-CHO)、 端醛基聚N-乙烯基己内酰胺(PNVCL-CHO)和端氨基聚己内酯(H₂N-PCL), 利用希夫碱反应, 进一步制备了基于亚胺键的聚乙二醇单甲醚-b-聚己内酯(MPEG-b-PCL)和聚N-乙烯基己内酰胺-b-聚己内酯(PNVCL-b-PCL)嵌段共聚物, 对共聚物结构进行了确认. 以MPEG-b-PCL和PNVCL-b-PCL为构筑单元, 制备了共聚物复合胶束, 研究了复合胶束对阿霉素的包载、 释放性质和细胞毒性等. 研究结果表明, 室温下MPEG-b-PCL和PNVCL-b-PCL能够在水中自组装形成以PCL为核、 MPEG和PNVCL为混合壳的共聚物复合胶束, 在生理温度下, 温敏性PNVCL链段发生相变塌缩在PCL核表面, 能够防止药物扩散释放, 亲水性MPEG链段形成可控通道. 药物体外释放结果表明, 在弱酸性环境中, 亚胺键能够断裂, 胶束被破坏, 促进药物的释放, 噻唑蓝(MTT)实验表明, 复合胶束的细胞毒性较低.     

水溶性高分子担载二茂铁希夫碱的合成

合成了水溶性聚丙烯酸－N－乙烯基吡咯烷酮和聚甲基丙烯酸－N－乙 基吡咯 烷酮担载的二茂铁希夫碱，并用元素分析，FT－IR，UV－Vis，热分析，XPS，ICP ，小角激光散射（LALLS）等分析方法对其结构和组成进行了表征。     

可控相转变温度热敏高分子的制备及其在免疫分析中的应用

合成了一种新型的快速响应热敏高分子聚N－异丙基丙烯酰胺－丙烯酰胺[P(NIP-co-AA)]，通过改变丙烯酰胺的含量可以改变高分子的临界溶解温度（LCST），使之用于不同用途。其中，将相转变温度（Ttr)在37℃的热敏高分子用于免疫分析的载体，建立了夹心型荧光免疫分析兔IgG的新方法。与聚N－异丙基丙烯酰胺（PNIP）作载体相比，两灵敏度相当，但由于相转变温度的提高，使得免疫反应的温度更接近于生物体的生理环境，并使免疫反应速率得到提高。该方法线性范围为0-1000μg/L；检出限为10μg/L。用于兔血清中兔IgG的测量，结果令人满意。     

Radiation polymerization of thermo-sensitive poly (N-vinylcaprolactam)

Temperature-sensitive poly (N-vinylcaprolactam) both in water-soluble state and in gel was prepared by γ-radiation polymerization. The effects of radiation dose, radiation dose rate and monomer concentration on polymerization and the low critical solution temperature characteristics of the polymer were studied. The results show that the polymer prepared within certain radiation dose (beyond 2 kGy) and dose rate range (2–14 Gy/min) has good temperature sensitivity and uniformity.     

Radiation-induced solid-state polymerization of derivatives of methacrylic acid. II. Postirradiation polymerization of octadecyl methacrylate

Octadecyl methacrylate (mpc ≈ 12°C.) polymerized readily in the solid state in the temperature range ?30 to +12°C. after gamma irradiation at ?196°C. The initial rate of polymerization and the “limiting” conversion increased with radiation dose and temperature. The temperature dependence of the rate corresponded to an “apparent” activation energy of 20 kcal./mole. Difficulties were experienced with polymerization during separation of the polymer from residual monomer, but these were minimized by using low radiation doses and a hot, selective solvent. The maximum conversion achieved was 70%. The polymer was crosslinked, even at low conversions.     

极性介质中醋酸乙烯酯的辐照引发分散聚合

用钴 60γ射线引发醋酸乙烯酯的分散聚合 ,通过选择各种极性溶剂体系 ,确立了醋酸乙烯酯在极性介质中稳定的分散聚合体系 .对异丙醇 水体系 ,聚合物分子量随剂量率的降低、稳定剂含量的增加、单体浓度的增大、反应温度的升高以及醇水比的降低而增加 .运用XPS、元素分析等表征聚合物粒子 ,及通过辐射接枝理论的分析 ,可以判断稳定剂所起的稳定作用主要是以物理吸附为主     

Living free‐radical polymerization of styrene under a constant source of γ radiation

Living polymerization of styrene was observed using γ radiation as a source of initiation and 1‐phenylethyl phenyldithioacetate as a reversible addition–fragmentation chain transfer (RAFT) agent. The γ radiation had little or no detrimental effect on the RAFT agent, with the molecular weight of the polymer increasing linearly with conversion (up to the maximum measured conversions of 30%). The polymerization had kinetics (polym.) consistent with those of a living polymerization (first order in monomer) and proportional to the square root of the radiation‐dose rate. This initiation technique may facilitate the grafting of narrow polydispersity, well‐defined polymers onto existing polymer surfaces as well as allow a wealth of kinetic experiments using the constant radical flux generated by γ radiation. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 19–25, 2002     

Temperature effects on γ-initiated polymerization of styrene. III. Conversion in the range 150–200°C

Experimental data are presented for the polymerization of commercial styrene in a γ-radiation flux of 20–51 rad/sec in the temperature range of 150–200°C. At radiation intensities above 20 rad/second, conversion rate is independent of dose rate over the range. Above 165°C, radiation does not enhance the conversion rate but does produce more rapid elimination of residual monomer. Molecular weights of polymer product in this temperature range are too low to be of commercial interest. An optimal temperature range of 110–120°C is suggested for the process.     

Formation of monodisperse polyacrylamide particles by radiation-induced dispersion polymerization: particle size and size distribution

Polyacrylamide microparticles were directly produced by radiation-induced dispersion polymerization in aqueous alcohol media using poly(N-vinylpyrrolidone) as a steric stabilizer at room temperature. The hydrodynamic diameter of a polymer particle and its distribution were measured on a dynamic laser light-scattering spectrometer. This method takes advantages of the specialties of radiation induction, and highly uniform polymer microspheres were obtained with high conversion. The number of the particle produced in the early stage of the polymerization was found to be constant during the remainder of the polymerization. The effects of various polymerization parameters, such as absorbed dose rate, monomer concentration, stabilizer content, medium polarity, and polymerization temperature on the particle size and size distribution were systematically investigated.     

A positron lifetime study of the electron-beam-induced polymerization of 1,6-hexanediol diacrylate

Positron lifetime measurements have been used to characterize the electron-beam-induced polymerization of 1,6-hexanediol diacrylate (HDODA). Lifetimes were measured as a function of radiation dose over a range of 0.5–7.0 Mrad and analyzed into three components. All three components exhibited some variation with radiation dose. Variations in the longest lifetime component have been interpreted in terms of changes in free volume. These data have been compared with polymer fraction data for electron-irradiated HDODA obtained by gel extraction and by NMR measurements. The positron lifetime parameter that correlates most closely with polymerization as measured by those techniques is the intensity of the longest lived component.     

Radiation-induced emulsion copolymerization of tetrafluoroethylene with propylene. IV. Effects of emulsifier concentration and dose rate

Radiation-induced emulsion copolymerization of tetrafluoroethylene with propylene was carried out by batch operation with an initial molar ratio of tetrafluoroethylene to propylene of 3.0 in the emulsifier concentration range of 0.1 to 3.0% and in the dose rate range of 2 × 10⁴ to 2 × 10⁵ R/hr. The effects of emulsifier concentration and dose rate on the polymerization rate and the number-average degree of polymerization are discussed in comparison with the Smith-Ewart theory. The polymerization rate is proportional to the 0.26 power of emulsifier concentration and to the 0.7 power of dose rate. The degree of polymerization is independent of the emulsifier concentration and the dose rate above the critical micelle concentration (CMC) of the emulsifier. These results are not in agreement with the Smith-Ewart theory. It is explained that the termination reaction is a degradative chain transfer of propagating radicals to propylene. On the other hand, the copolymerization in emulsion occurs either below the CMC or in the absence of emulsifier. Under these conditions, however, it is impossible to obtain a copolymer of high molecular weight at a high rate of polymerization because of the presence of a small number of polymer particles formed and the short interval of chain growth in the polymer particle.     

双官能度引发剂引发苯乙烯聚合微观动力学

采用 2 ,5 二甲基 2 ,5 二己酰基过氧化己烷 (DMDEHPH)为引发剂 ,在 5 5～ 80℃下引发苯乙烯聚合 .通过研究影响聚合速率的各种因素 ,得出了聚合速率对单体浓度和引发剂浓度的级数分别为 1 0和 0 5次、聚合活化能为 92 0kJ mol、引发效率为 0 5 5± 0 0 3.温度一定 ,引发效率随引发剂浓度的增加而减小 .求得 6 0和70℃下DMDEHPH向引发剂的链转移常数分别为 0 0 37和 0 0 4 8、向单体的链转移常数分别为 0 5 9× 10 - 4和0 75× 10 - 4.     

Effect of dose rate on radiation-induced polymerization of styrene adsorbed on silica gel

The effect of dose rate on the rate of polymerization and molecular weight distribution of radiation-induced polymerization of styrene adsorbed on silica gel was studied in a wide dose rate range of 4.4 × 10⁴ to 3 × 10⁸ rad/hr by γ rays of ⁶⁰Co and electron beams with a Cockcroft-Walton-type accelerator. Dose rate dependence on the initial rate of polymerization was about 1 below 3 × 10⁷ rad/hr, and it decreased gradually at high dose rates. Throughout the dose rate range, graft polymerizations and homopolymerizations by cationic and radical mechanisms proceeded simultaneously. Dose rate dependence of the cationic polymerization was 1 below 3 × 10⁷ rad/hr, while dose rate dependence of the radical polymerization was 0.65 below 3 × 10⁷ rad/hr. At high dose rates, molecular weight and fraction of graft polymer decreased, and fraction of cationic polymerization increased. A very high-molecular-weight graft polymer was formed above 4.4 × 10⁵ rad/hr at the initial stage of the polymerization. The dose rate dependence of this polymerization was larger than 1 and decreased with increase in dose rate. The polymerization seems to be related to an excitation of monomer or growing chain.