聚(苯乙烯-alt-马来酸酐)-b-聚苯乙烯亲水/亲油嵌段共聚物在溶液中的聚集行为研究

采用RAFT方法合成了由马来酸酐／苯乙烯和苯乙烯组成的交替序列两嵌段共聚物P(MAn-alt-St)-b-PSt。将其中的马来酸酐用PEO进行水解,得到了支化的亲水亲油两嵌段共聚物。通过H—NMR和IR对共聚物的结构组成进行表征。以二甲基氨基黄酮化舍物为荧光探针,测定了形成共聚物胶束的临界浓度(CMC)。用TEM和SEM现察不同酸碱条件下所得纳米材料形貌,并对其形成机制进行了讨论。     

两亲聚合物胶束自组装包药研究进展

两亲聚合物胶束具有突出的理化性能和独特功能,能够在溶液中自组形成具有核壳结构的聚合物胶束,同时实现药物的负载。自组装包药技术能够缓解我国药物辅料缺乏的现状,符合目前药物辅料发展的新趋势。通过自组装形成的聚合物胶束在药物控释、药物靶向载体、药物制剂开发、新型药物辅料等方面具有广阔的应用前景。本文综述了两亲聚合物胶束自组装包载药物的原理以及方法,重点介绍了三类两亲聚合物在自组装包药方面的最新研究成果和发展趋势。本文还对载药胶束在药物释放方面的应用进行了概述。     

含氟两亲接枝共聚物的制备及其与牛血清蛋白作用的研究

用端基反应法合成了对乙烯基苄基的聚乙二醇大分子单体,将该大分子单体与甲基丙烯酸六氟丁酯共聚,合成了一种含氟两亲接枝共聚物.利用1H-NMR1、9F-NMR、GPC对大分子单体和两亲接枝共聚物进行了表征.表面张力法测定了两亲接枝共聚物的临界胶束浓度,发现随着共聚物中含氟链段含量的增加,其临界胶束浓度降低.采用荧光光谱研究了含氟两亲接枝共聚物与牛血清蛋白(BSA)的相互作用,结果表明由于含氟链段疏水力的作用,含氟两亲接枝共聚物能与牛血清蛋白发生相互作用使其荧光增强,随着含氟两亲接枝共聚物浓度和共聚物中含氟链段含量的增加,荧光增强幅度加大.通过透射电子显微镜(TEM)和激光光散射粒度仪(PCS)测试发现,当BSA加入到含氟两亲接枝共聚物的胶束溶液后,所得胶束的粒径和粒径分布变大,共聚物胶束由规整的实心核壳结构变为囊泡状核壳结构.     

两亲嵌段共聚物胶束用作医用材料

两亲嵌段共聚物可以在水溶液中自组装形成亲水性链段为外壳、疏水性链段为内核的胶束,这种胶束能够用作药物载体而引起人们极大的关注。本文综述了两亲嵌段共聚物胶束用作医用材料的研究进展,主要内容包括医用两亲嵌段共聚物的种类,胶束化,以及用作诊断试剂载体、药物缓释载体、靶向载体等。两亲嵌段共聚物胶束用作磁共振造影剂载体有利于肿瘤的诊断,用作药物缓释载体可以有效增溶难溶性抗肿瘤药物,延长药物在体内的血液循环时间。此外,通过对胶束表面进行修饰或者施加外场,还可以实现靶向功能。因此,两亲嵌段共聚物胶束在医用材料领域有着广阔的发展前景。     

两亲分子结构对铜网表面生长的Cu2S纳米材料形貌的影响

观察到两亲分子的结构对铜网表面生长的Cu2S一维纳米材料的形貌有较大的影响,含羧酸的强亲水型两亲分子--N-硬脂酰-L-谷氨酸有助于形成纳米线,而把两个羧基全部转化为酯基后,则倾向于形成具有分形结构的纳米带.     

嵌段结构对两亲嵌段共聚物水溶液行为的影响

在合成了二种具有相同组成不同嵌段结构排布的共聚物基础上对它们溶液的物理化学行为用荧光探针的方法进行了研究，结果表明：由于结构排布的不同其物理化学行为有着较大的差异，三嵌段结构的共聚物较二嵌段者更易于形成胶束体系，而二嵌段共聚物则易于发生凝胶化，对上述结果进行讨论和解释．     

两亲嵌段共聚物溶液内胶束形成的温度效应

合成了一系列具有两亲嵌段结构的聚（乙二醇）（PEO）一聚（丙二醇）（PPO）共聚物．利用荧光探针及示差量热法测定了共聚物水溶液的临界胶束形成温度（CMT）值．发现二嵌段共聚物（PEO－PPO）和三嵌段共聚物（PEO－PPO－PEO）有着类似的变化规律，即随共聚物分子中疏水链（PPO）长度的增大，其CMT值降低．但三嵌段共聚（PPO－PEO－PPO）则因疏水链段处于共聚物分子的两端，因而在溶液中有可能形成立体网状交联结构．此外，利用探针分子在不同极性溶剂中荧光峰值波长发生位移的现象可以对形成胶束内核的组织程度、极性大小进行估测．     

两亲接枝共聚物PECA-g-PEG胶束的CMC及表面带电性

两亲接枝共聚物PECA-g-PEG胶束的CMC及表面带电性;两亲共聚物;聚氰基丙烯酸乙酯-g-聚乙二醇;临界胶束浓度;聚沉     

两亲分子结构对铜网表面生长的Cu2S纳米材料形貌的影响

观察到两亲分子的结构对铜网表面生长的Cu2S-维纳米材料的形貌有较大的影响，含羧酸的强亲水型两亲分子——N-硬脂酰-L-谷氨酸有助于形成纳米线，而把两个羧基全部转化为酯基后．则倾向于形成具有分形结构的纳米带。     

Hydrotrope型两亲化合物的合成和自缔合研究

合成了一种hydrotrope型可聚合两亲化合物4-(2-(丙烯酰氧基)乙氧基)苯甲基三乙基溴化铵(AEBA),应用紫外吸收光谱和荧光探针技术研究了它的溶液性质和自缔合作用,实验结果表明,AEBA在水溶液中具有较高的自缔合能力、表面活性和增溶作用,它对油溶性染料荧光素二乙酸酯(fluorescein diacetate,FDA)的最小助溶浓度(minimum hydrotrope concentration,MHC)约为0.05 mol/L,AEBA分子间缔合形成不同于表面活性剂胶束结构的堆砌状(stack-type)聚集体结构。     

聚丙烯酰胺/聚L-谷氨酸苄酯接枝共聚物的合成及其胶束制备

以聚丙烯酰胺(PAM)为大分子引发剂, 采用开环聚合方法, 在N,N-二甲基甲酰胺(DMF)中引发L-谷氨酸苄酯环内酸酐(BLG-NCA)聚合合成了两亲性聚丙烯酰胺/聚L-谷氨酸苄酯接枝共聚物(PAM-g-BLG), 采用IR, 1H NMR和GPC方法对共聚物结构进行了表征; 用芘作荧光探针, 研究了共聚物胶束的形成及其临界胶束浓度(cmc), 利用动态光散射(DLS)和透射电镜(TEM)研究了胶束的粒径分布和形态. 结果表明, PAM能够引发BLG-NCA开环聚合得到接枝共聚物, 在一定条件下接枝共聚物能够形成球形的稳定胶束, cmc值和胶束粒径随着共聚物中疏水性聚L-谷氨酸苄酯(PBLG)链段含量的增加而减小.     

Synthesis and characterization of a novel amphiphilic biodegradable β-cyclodextrin/poly(γ-benzyl L-glutamate) copolymer

β-Cyclodextrin/poly(γ-benzyl L-glutamate) (β-CD-PBLG) copolymers were synthesized by ring-opening polymerization of N-carboxy-γ-benzyl L-glutamate anhydride (BLG-NCA) in N,N-dimethylformamide (DMF) initiated by mono-amino-β-cyclodex-trin(H2N-β-CD). The structures of the copolymers were confirmed by IR, 1H NMR and GPC. The fluorescence technique was used to determine the critical micelle concentrations (CMC) of copolymer miceU solution, the diameter and the distribution of micelles were characterized by DLS. The results showed that BLG-NCA could be initiated by H2N-β-CD to produce copolymer. The nano-micells were formed by these copolymers in water.     

Effects of SDS on the thermo- and pH-sensitive structural changes of the poly(acrylic acid)-based copolymer containing both poly(N-isopropylacrylamide) and monomethoxy poly(ethylene glycol) grafts in water

The effects of SDS on the structural changes of the thermally induced polymeric micelles from a graft copolymer comprising poly(acrylic acid) (PAAc) as the backbone and poly(N-isopropylacrylamide) (PNIPAAm) and monomethoxy poly(ethylene glycol) (mPEG) as the grafts in aqueous solution are studied. At low temperature, SDS micelles form via the hydrophobic association of SDS molecules with the PNIPAAm grafts at a critical aggregation concentration of SDS (cac(SDS)) much lower than its critical micelle concentration. Consequently, the critical aggregation temperature of the graft copolymer is elevated. The corresponding structure of the thermally induced polymeric micelles is characterized by an abrupt reduction in the particle size and an increased tendency toward formation of the monocore structure with a more compact and hydrophobic PNIPAAm microdomain being developed. On the other hand, upon the polymeric micelle formation at high temperature, the copolymer-bound SDS micelle structure is disrupted and the dissociated SDS molecules migrate to the core-shell interface with their alkyl chains residing in the liquidlike region of the hydrophobic PNIPAAm microdomain. The correlation between the polymeric particles and copolymer-bound micelles is further substantiated by showing the change of the colloidal particle size in response to changes in cac(SDS) via adjusting the pH of the aqueous copolymer/SDS solutions.     

Study on polymeric micelles of poly(γ-benzyl l-glutamate)-graft-poly(ethylene glycol) copolymer and its mixtures with poly(γ-benzyl l-glutamate) homopolymer in ethanol

Poly(γ-benzyl l-glutamate)-graft-poly(ethylene glycol) (PBLG-graft-PEG) copolymer was synthesized by the ester exchange reaction of the PBLG homopolymer with PEG. NMR spectroscopy was used to confirm the composition of the PBLG-graft-PEG copolymer. FTIR spectroscopy was used to characterize the chain conformation of polypeptide segments in the PBLG-graft-PEG copolymer in solid state. The self-assembly behavior of PBLG-graft-PEG and its mixtures with PBLG in ethanol were investigated by transmission electron microscopy (TEM) and viscometry. Experimental results showed that the PBLG-graft-PEG copolymer can self-assemble to form polymeric micelles with a core-shell structure of a thin shuttle-like shape. The introduction of the PBLG homopolymer into the mixed system not only decreases the critical micelle concentration (CMC) but also changes the morphology of the micelles from their shuttle-like shape to cylindrical shape. The effects of test temperature on the critical micelle concentration of PBLG-graft-PEG were also studied.     

四乙基氢氧化铵水溶液的临界胶束浓度的测定

使用电导率法测定了四乙基氢氧化铵水溶液的第2和第2临界胶束浓度(CMC),其值分别为0.52和38.0 mmol/L。同时在无探针分子条件下用循环伏安法(CV)研究了四乙基氢氧化铵水溶液体系胶束在铂电极(Pt)上的电化学行为,得到1个受扩散控制的氧化峰,并用电位阶跃计时库仑法(CC)测定了胶束的扩散系数,得到了四乙基氢氧化铵的第1和第2临界胶束浓度分别为0.52和41.0 mmol/L。通过以上2种方法的测定,可以确定四乙基氢氧化铵的第1和第2临界胶束浓度分别为0.52和39.5 mmol/L。电导率法和计时库仑法各具特点,均不失为测定表面活性剂临界胶束浓度的好方法。     

Micellization in aqueous solution of an ethylene oxide-propylene oxide triblock copolymer, investigated with 1H NMR spectroscopy, pulsed-field gradient NMR, and NMR relaxation

(1)H nuclear magnetic resonance (NMR) spectroscopy has been applied to study the temperature and concentration-induced micellization of a poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) triblock copolymer, Pluronic P105, in D(2)O solutions in the temperature range from 5 to 45 degrees C and the concentration range from 0.01 to 15% (w/v). The intrinsic probes, the chemical shift, and the half-height width of the PO CH(3) signal are very sensitive to the local environment and can be used to characterize the temperature and concentration-dependent aggregation process. When the temperature approaches the critical micellization temperature or the polymer concentration reaches the critical micellization concentration, the chemical shift of the PO CH(3) signal moves toward lower ppm values and the half-height width of the PO CH(3) signal shows a sudden increase. It indicates that the methyl groups are experiencing a progressively less polar environment and transferring from water to the hydrophobic micellar core. The hydrodynamic radius of the unimers and the micelles are determined as be 1.8 and 5.0 nm by means of pulsed-field gradient spin-echo (PGSE) NMR. They were independent of temperature and concentration. The drastic shortening of spin-lattice relaxation time T(1) for the PO CH(3)/CH(2) protons in the transition region suggested that the PPO blocks are located in a "liquid-like" micellar core, whereas the exponential increase of T(1) for the PEO CH(2) protons implied that the PEO blocks are still keeping in contact with surrounding water. Thermodynamics analysis according to a closed association model shows that the micellization process is entropy-driven and has an endothermic micellization enthalpy.     

两亲接枝共聚物PS-g-N-PEO的合成及表面性能研究——铸膜溶剂及浓度的影响

采用大分子单体法合成了一系列聚苯乙烯接枝壬基酚聚氧乙烯 (PS g NPEO)两亲共聚物 ,采用溶液铸膜法将其在PET表面制膜 ,并利用扫描电子显微镜 (SEM) ,X射线光电子能谱 (XPS) ,衰减全反射红外光谱(ATR)和水接触角 (CA)等手段研究了共聚物组成、铸膜溶剂及浓度对共聚物膜表面形貌、组成及水浸润性能的影响 .结果表明 ,两亲接枝共聚物在不同条件下可形成规则的表面微孔 ,共聚物中NPEO含量越高 ,共聚物膜表面微孔孔径越大 ,对应的水接触角越小 .以THF为铸膜溶剂时 ,制膜浓度越大 ,共聚物膜表面微孔孔径越大 ,对应的水接触角越小 ;而以甲苯为溶剂时 ,制膜浓度对共聚物膜表面形貌影响不大 ,但水接触角要较THF体系显著降低 ,水接触角与浓度关系与THF体系相反 ,制膜浓度越大 ,对应的水接触角越大 .制膜浓度相同时 ,THF作溶剂 ,共聚物膜微孔较大 ,表面亲水组分含量较低 ;以甲苯为溶剂 ,微孔较密 ,表面亲水组分较高 .     

Pickering Emulsion Stabilized by Self-Assembled Micelles of Amphiphilic Random Copolymer P(St-co-DM)

Self-assembled polymeric micelles can be used as efficient particulate emulsifiers. Styrene (St) and dimethylaminoethyl methacrylate (DM) were used to synthesize the amphiphilic random copolymer P(St-co-DM). This copolymer self-assembles into spherical polymeric micelles. The polymeric micelles show surface activity and pH sensitivity for producing Pickering emulsion. The experiment shows that the stability of the emulsion increases with the micelle concentration. The emulsion can only be formed when the salt concentration is below a certain limiting value. Using the white oil as the oil phase, polymeric micelles have emulsification in a large pH range. The emulsifying performance of the polymeric micelles could be enhanced by raising the water/oil volume ratio.      

Synthesis and Characterization of Thermo-responsive Poly(N-vinyl-2-pyrrolidinone)-block-poly(N-isopropylacrylamide) Micelles

A novel thermo-responsive diblock copolymer of poly(N-vinyl-2-pyrrolidinone)-block-poly(N-isopropylacrylamide) (PNVP-b-PNIPAM) was synthesized. FT-IR, ¹H-NMR and SEC results confirmed the successful synthesis of PNVP-b-PNIPAM diblock copolymer via anionic polymerization. The polymeric micelles formed from PNVP-b-PNIPAM copolymer in aqueous solution were developed and characterized as a potential thermo-responsive and biocompatible drug delivery system. Micellization of the diblock copolymer in aqueous solution was characterized by dynamic laser scattering (DLS), turbidity measurement, tension measurement and transmission electron microscopy (TEM). The thermo-responsive polymeric micelles with the size ranges of 200 to 260 nm and thickness of 30 nm are localized, selected and targeted for drug release, having a great potential in response to external-stimulus such as temperatures from 35 to 39°C. The critical micellization concentration (cmc) of PNVP-b-PNIPAM in aqueous solution is 0.0026 wt% determined by turbidity measurement. The size of micelles determined by DLS increased from 163 to 329 nm with increasing concentration of PNVP-b-PNIPAM from 0.25 to 0.5 wt% in aqueous solution at 40°C, which is determined by DLS.     

SYNTHESIS OF AMPHIPHILIC COPOLYMERS BASED ON ACRYLATES BY FREE-RADICAL POLYMERIZATION AND THEIR APPLICATION IN ALKYD EMULSIONS

Novel amphiphilic copolymers which contained poly(ethylene glycol) side-chain, long-chain alkyl pendant groups, and carboxyl groups have been synthesized by the conventional free-radical copolymerization of special monomers. The products were characterized by analysis of Fourier transform infrared spectroscopy (FT-IR), Gel Permeation Chromatography (GPC), and ¹H NMR. Based on the measurement of surface tension of aqueous copolymer solutions with various concentrations at an air/water interface, the critical micelle concentrations (CMC) was found to be lower along with the increase of copolymer concentration. Experimental results showed that CMC of this kind of amphiphilic polymer appeared in the range of 0.01～0.1 g/L. The amphiphilic polymer was mixed with an anionic surfactant (SDBS) in different proportions at aqueous solution and then successfully used in the preparation of alkyd emulsions. The results were compared with those of alkyd emulsions without polymeric surfactant. Steric stabilization of amphiphilic polymer was investigated by the observation of the stability of alkyd emulsions. The emulsions were stable after resting at ambient temperature for four months.