三维宏观网络状囊泡薄膜的分级自组装研究

分别合成以疏水性超支化聚醚(HBPO)为核,以亲水性聚环氧乙烷(EO)和聚甲基丙烯酸N,N-二甲氨基乙酯(DMAEMA)为臂的两亲性超支化多臂共聚物HBPO-star-PEO和HBPO-star-PDMAEMA.通过两者在水溶液中的复合自组装制备得到具有pH响应性的巨型聚合物囊泡(1~10μm),并用zeta电位仪,激光共聚焦显微镜及光学显微镜对囊泡的自组装行为进行了研究.结果表明,在等电点以前,复合囊泡始终以单个囊泡形式存在;随着溶液pH的升高,囊泡逐步线型缔合成串珠结构;在更高的pH下,囊泡进一步二次聚集形成具有宏观尺度的三维蜘蛛网状超分子结构,这是一类新的自组装体.     

甲基丙烯酸(N,N-二甲氨基)乙酯的自引发催化氧化聚合

作为一种自身还原性单体,甲基丙烯酸(N,N-二甲氨基)乙酯(DMAEMA)可与部分氧化剂构成氧化还原引发剂体系,并引发自身的聚合.为验证该假设,进行了以CuCl2络合物催化DMAEMA的本体氧化聚合.动力学研究表明,所得聚合物的分子量随着聚合时间的延长而逐渐增加.核磁波谱分析表明,低转化率下所得低聚物同时含有甲基丙烯酸酯末端和C-Cl端基,显示DMAEMA的二甲氨基(N-CH3)被CuCl2氧化成单体自由基(N-CH2·),并通过原子转移自由基聚合(ATRP)机理形成聚合物.由于叔胺广泛地用作ATRP的络合物,由此可见,在传统ATRP体系中,来自CuCl2/叔胺的氧化还原引发不可忽略.     

原子转移自由基聚合制备聚甲基丙烯酸(N-羟基琥珀酰亚胺)酯及其嵌段共聚物

以CuCl/N-苄基-2-吡啶基甲亚胺(NBPM)/2-溴异丁酸乙酯(EBrIB)作为引发催化体系,使甲基丙烯酸(N-羟基琥珀酰亚胺)酯(MASI)进行ATRP聚合,得到的聚甲基丙烯酸(N-羟基琥珀酰亚胺)酯(PMASI)具有较高的单体转化率(90%)、较窄PDI(~1.10)和较高的分子量。在整个聚合过程中,较强的C—Cl键仍使聚合物的端基保持活性,有利于与第二单体甲基丙烯酸(N,N-二甲氨基)乙酯(DMAEMA)嵌段共聚形成结构明确的嵌段共聚物P(MASI-b-DMAEMA)。当MASI的链长较短时,P(DMAEMA40-b-MASI16)具有水溶性并可自组装成直径均匀的核-壳型微胶束,间接证明了聚合过程的可控特征。     

嵌段聚合物PGMA-b-PDEAEMAx的合成及其CO2诱导解组装行为

以甲基丙烯酸二乙基氨基乙酯为疏水段,聚甲基丙烯酸甘油酯为亲水段,采用可逆加成-断裂转移聚合合成了具有不同嵌段比例的甲基丙烯酸甘油酯-b-甲基丙烯酸二乙氨基乙酯二嵌段聚合物(PGMA-b-PDEAEMAx),其结构经1H NMR和GPC表征。聚合物通过自组装形成球形胶束、线性胶束聚集体和囊泡结构;向聚合物溶液中通入CO2后,其自组装解体。     

主链含酯键的基于聚甲基丙烯酸二甲氨基乙酯的共聚物合成与表征

通过己内酯(CL)和甲基丙烯酸二甲氨基乙酯(DMAEMA)的杂化聚合制备了主链含酯键结构单元的聚甲基丙烯酸二甲氨基乙酯的共聚物,并通过核磁(~1H-NMR)、凝胶渗透色谱(GPC)、示差扫描量热仪(DSC)等对聚合物的结构和性能进行了表征.结果表明,膦腈碱t-Bu P4能高效催化CL和DMAEMA的杂化聚合,得到含CL和DMAEMA 2种结构单元的刺激响应性可降解共聚物.该共聚物只存在一个玻璃化转变温度且共聚物组成与单体投料比接近.GPC数据表明共聚物的数均分子量范围为1.63×10~4~2.47×10~4,分子量分布为2.11~2.54.酯键的引入赋予了聚合物良好的降解性能,同时使其低临界相转变温度(LCST)从52.6℃降到了44.5℃.TEM结果表明得到的共聚物能够在水中形成平均直径约60 nm的胶束.     

酶触发聚合物囊泡-核交联胶束转变用于响应性抗菌剂释放

通过使用药物运载体系来提高抗菌物质的使用效率是应对抗生素耐药性的有效途径.本文报道了一种制备细菌酶响应聚合物囊泡作为"智能型"抗菌剂载体的方法.通过可逆加成-断裂链转移聚合(RAFT)制备的脂酶和硝基还原酶响应的二嵌段共聚物PEG-b-PA和PEG-b-PN,能够在水溶液中自组装形成聚合物囊泡组装体.该囊泡组装体在没有酶存在的条件下相对稳定,而在脂酶或硝基还原酶的作用下发生从囊泡到核交联胶束的形貌转变.基于这一转变过程实现了负载在囊泡中的抗菌剂(三氯生,抗菌肽Parasin Ⅰ和溶菌酶)的选择性释放,并研究了针对大肠杆菌(E.coli,革兰氏阴性菌)、金黄色葡萄球菌(S.aureus,革兰氏阳性菌)和白色念珠菌(C.albicans,真菌)的生长抑制效果.     

GHD室温自交联乳液的聚合及贮存稳定性

采用半连续种子乳液聚合技术合成了含甲基丙烯酸缩水甘油酯(GMA)、甲基丙烯酸羟乙酯(HEMA)和甲基丙烯酸二甲氨基乙酯(DMAEMA)的室温自交联乳液(GHD).实验结果表明,在甲基丙烯酸甲酯(MMA)-丙烯酸丁酯(BA)-GMA种子乳液存在下,聚合温度升高,聚合过程稳定性下降,但乳液的贮存稳定性提高;乳化单体滴加速度加快,种子聚合物的玻璃化温度升高,可减少聚合过程的交联凝聚作用,提高聚合过程的稳定性;而HEMA和DMAEMA用量增加对聚合过程的稳定性没有明显影响,但使乳液的贮存稳定性下降.官能团间的交联凝聚作用可能是影响室温自交联乳液聚合及贮存过程稳定性的关键因素.     

水相光引发聚合诱导自组装制备嵌段共聚物纳米材料

本文以聚甲基丙烯酸甘油酯(PGMA)作为大分子链转移剂、甲基丙烯酸羟丙酯(HPMA)为单体、苯基钠盐-三甲基苯甲酰亚磷酸盐(SPTP)为引发剂,通过水相光引发可逆加成-断裂链转移(RAFT)分散聚合制备了一系列PGMA-b-PHPMA共聚物纳米材料。考察了水相光引发聚合诱导自组装的反应动力学,在温和条件下(水相、可见光和室温)成功得到不同形貌的聚合物纳米材料(球形、纤维和囊泡),并进一步探究了反应条件对嵌段聚合物形貌的影响。聚合反应的激活或暂停都可以通过对光源的简单"开/关"进行控制。     

大投料比下自缩合原子转移自由基共聚合中聚合物支化结构的形成与演化

研究了少量N-[4-(α-溴代异丁酰氧基)苯基]马来酰亚胺(BiBPM)与大量甲基丙烯酸-N,N-二甲氨基乙酯(DMAEMA)在CuBr/N,N,N′,N″,N″-五甲基二乙烯三胺(PMDETA)催化下的自缩合原子转移自由基共聚合(SCATRCP).分别利用气相色谱、三检测凝胶渗透色谱测定了聚合反应过程中DMAEMA的转化率、所得聚合物(PDMAEMA)的分子量与分子量分布、绝对分子量和特性黏数等随着反应时间的变化.结果表明,在以上聚合过程中,PDMAEMA的分子量随着聚合的进行而不断上升,但是支化度持续下降.由此可知,在聚合早期就形成了低分子量而高支化度的PDMAEMA,在聚合后期,主要进行DMAEMA的ATRP,导致支化度随着分子量的上升而逐渐下降.     

原子转移自由基法一锅合成具有pH响应性的新型糖聚合物

本文利用原子转移自由基聚合法(ATRP),通过连续投料法在室温下一步合成了具有pH响应性质的糖聚合物,并且简单地通过控制甲基丙烯酸-2-二甲氨基乙酯(DMAEMA)、甲基丙烯酸-2-二乙氨基乙酯(DEAEMA)单体投料比即实现了对糖聚合物胶束的临界pH转变点在人体生理pH值附近的调节,这对于设计新型的药物控释系统具有重要意义.此外,糖聚合物中的P(DMAEMA-co-DEAEMA)嵌段在一定条件下为带正电荷的聚电解质.因此,本文中合成的糖聚合物不但可以用作传统憎水药物的载体,还可望成为带有负电荷的新型药物例如单链DNA(ssDNA) 等的载体.     

具有二氧化碳响应性的纳米球形聚电解质刷的制备及其乳化性能

以聚苯乙烯(PS)纳米球为核,利用紫外光引发聚甲基丙烯酸N,N-二甲基氨基乙酯(PDMAEMA)接枝到PS纳米球上,得到对CO_2有刺激响应的聚甲基丙烯酸N,N-二甲基氨基乙酯刷(PS-PDMAEMA)。动态光散射(DLS)、电导率结果表明PS-PDMAMEA具有CO_2刺激响应性。该微粒可以作为Pickering乳液的乳化剂,通过导入CO_2或N_2作为开关,进而破坏或稳定Pickering乳液。用数码照片、偏光显微镜等方法表征了乳液的稳定情况。结果表明:PS-PDMAEMA具有很好的CO_2刺激响应性,利用PS-PDMAEMA作为乳化剂稳定Pickering乳液,仅仅依靠气体开关(CO_2或N_2)就可改变乳液的稳定性。     

Light-regulated supramolecular engineering of polymeric nanocapsules

This article describes the light-driven supramolecular engineering of water-dispersible nanocapsules (NCPs). The novelty of the method lies in the utilization of an appropriate phototrigger to stimulate spherical polymer brushes, consisting of dual-responsive 2-(dimethylamino)ethyl methacrylate (DMAEMA) and light-sensitive spiropyran (SP) moieties, for the development or disruption of the NCPs in a controlled manner. The fabrication of the nanocarriers is based on the formation of H-type π-π interactions between merocyanine (MC) isomers within the sterically crowded environment of the polymer brushes upon UV irradiation, which enables the SP-to-MC isomerization of the photosensitive species. After HF etching of the inorganic core, dual-responsive polymeric vesicles whose walls' robustness is provided by the MC-MC cross-link points are formed. Disruption of the vesicles can be achieved remotely by applying a harmless trigger such as visible-light irradiation. The hydrophilic nature of the DMAEMA comonomer facilitates the engineering of the vesicles in environmentally benign aqueous media and enables the controlled alteration of the NCPs size upon variation of the solution pH. The inherent ability of the NCPs to fluoresce in water opens new possibilities for the development of addressable nanoscale capsules for biomedical applications.     

Synthesis and supramolecular organization of amphiphilic diblock copolymers combining poly(N,N-dimethylamino-2-ethyl methacrylate) and poly(epsilon-caprolactone)

Well-defined poly(epsilon-caprolactone) (PCL)/poly(N,N-dimethylamino-2-ethyl methacrylate (PDMAEMA) diblock copolymers were synthesized, and their self-assembly was investigated as micelles both in aqueous solutions and in thin solid deposits. The synthetic approach combines controlled ring opening polymerization (ROP) of epsilon-caprolactone (CL) and atom transfer radical polymerization (ATRP) of N,N-dimethylamino-2-ethyl methacrylate (DMAEMA). Diblock copolymers were prepared by ROP of CL initiated by (Al(OiPr)3), followed by quantitative reaction of the PCL hydroxy end-groups with bromoisobutyryl bromide. The alpha-isopropyloxy omega-2-bromoisobutyrate poly(epsilon-caprolactone) (PCL-Br) obtained was used as a macroinitiator for the ATRP of DMAEMA. The molecular characterization of those diblock copolymers was performed by 1H NMR spectroscopy and gel permeation chromatography (GPC) analysis. The self-assembly of the copolymers into micellar aggregates in aqueous media was followed with dynamic light scattering (DLS), as a function of concentration and the pH. In parallel, the morphology of the solid deposits of those micelles was examined with atomic force microscopy (AFM).     

Dispersion Polymerization of Methyl Methacrylate in Supercritical Carbon Dioxide in the Presence of Random Copolymers

Summary: Statistical random copolymers of 1H,1H‐perfluorooctyl methacrylate and 2‐dimethylaminoethyl methacrylate, poly(FOMA‐co‐DMAEMA), effectively stabilized the dispersion polymerization of methyl methacrylate in supercritical carbon dioxide. Free‐flowing, micron‐sized spherical PMMA particles could be produced with poly(FOMA‐co‐DMAEMA) containing 34 w/w% FOMA.

SEM image of PMMA particles prepared with poly(FOMA‐co‐DMAEMA) (34:66).     

甲基丙烯酸二甲胺乙酯对光固化阴极电泳漆性能的影响

通过自由基共聚合得到丙烯酸树脂,然后用甲基丙烯酸异氰酸乙酯(MOI)对其改性,合成了既带有N,N-二甲胺基,又带有乙烯基的紫外光固化阴极电泳漆基体树脂。研究了甲基丙烯酸二甲胺乙酯(DMAE-MA)用量对改性丙烯酸树脂水分散体和漆膜性能的影响规律。结果表明,树脂分子链上引入DMAEMA后,其水分散性有较大改善,随DMAEMA用量增加,水分散体的粒径减小、粘度略有增加、稳定性增强,电泳沉积量和漆膜厚度增加,电泳沉积漆膜的初期含水率增加。综合考虑水分散体和漆膜的性能,丙烯酸树脂中DMAEMA质量分数以0．144左右为宜。     

可聚合的二苯酮-脂肪叔胺光氧化还原体系敏化的丙烯腈光聚合

<正> 关于二苯甲酮-三级胺体系引发烯类单体光聚合的研究已有许多报道。其引发机理研究得也比较透彻。此类引发体系之所以引人注目,除其本身具有良好的引发效果外,还有重要的一点在于氧气对于此体系不但无阻聚作用,而且在一定条件下能够加速其聚合反应。甲基丙烯酸N,N-二甲氨基乙酯(DMAEMA)是可聚合的脂肪叔胺。有关芳香酮类如二苯甲酮。芴酮与DMAEMA构成的引发体系的研究已有城田等人和张举贤     

Synthesis and characterization of amphiphilic triblock polymers by copper mediated living radical polymerization

2-Dimethylaminoethyl methacrylate (DMAEMA) and 2-diethylaminoethyl methacrylate (DEAEMA) block copolymers have been synthesized by using poly(ethylene glycol), poly(tetrahydrofuran) (PTHF) and poly(ethylene butylenes) macroinitiators with copper mediated living radical polymerization. The use of difunctional macroinitiator gave ABA block copolymers with narrow polydispersities (PDI) and controlled number average molecular weights (M_n’s). By using DMAEMA, polymerizations proceed with excellent first order kinetics indicative of well-controlled living polymerization. Online ¹H NMR monitoring has been used to investigate the polymerization of DEAEMA. The first order kinetic plots for the polymerization of DEAMA showed two different rate regimes ascribed to an induction period which is not observed for DMAEMA. ABA triblock copolymers with DMAEMA as the A blocks and PTHF or PBD as B blocks leads to amphiphilic block copolymers with M_n’s between 22 and 24 K (PDI 1.24-1.32) which form aggregates/micelles in solution. The critical aggregation concentrations, as determined by pyrene fluorimetry, are 0.07 and 0.03 g dm⁻¹ for PTHF- and PBD-containing triblocks respectively.     

Block and random copolymers as surfactants for dispersion polymerization. I. Synthesis via atom transfer radical polymerization and ring‐opening polymerization

Atom transfer radical polymerization (ATRP) and ring‐opening polymerization (ROP) were combined to synthesize poly(?‐caprolactone‐co‐octadecyl methacrylate‐co‐dimethylaminoethyl methacrylate) copolymers possessing a triblock or random block structure. Various synthetic pathways (sequential or simultaneous approaches) were investigated for the synthesis of both copolymers. For the preparation of these copolymers, an initiator with dual functionality for ATRP/anionic ring‐opening polymerization, 2‐hydroxyethyl 2‐bromoisobutyrate, was used. Copolymers were prepared with good structural control and low polydispersities (weight‐average molecular weight/number‐average molecular weight < 1.2), but one limitation was identified: the dimethylaminoethyl methacrylate (DMAEMA) block had to be synthesized after the ?‐caprolactone block. ROP could not proceed in the presence of DMAEMA because the complexation of the amine groups in poly(dimethylaminoethyl methacrylate) deactivated tin(II) hexanoate, which was used as a catalyst for ROP. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1498–1510, 2005     

Cationic methacrylate copolymers containing primary and tertiary amino side groups: Controlled synthesis via RAFT polymerization,DNA condensation,and in vitro gene transfection

A versatile family of cationic methacrylate copolymers containing varying amounts of primary and tertiary amino side groups were synthesized and investigated for in vitro gene transfection. Two different types of methacrylate copolymers, poly(2‐(dimethylamino)ethyl methacrylate)/aminoethyl methacrylate [P(DMAEMA/AEMA)] and poly(2‐(dimethylamino)ethyl methacrylate)/aminohexyl methacrylate [P(DMAEMA/AHMA)], were obtained by reversible addition‐fragmentation chain transfer (RAFT) copolymerization of dimethylaminoethyl methacrylate (DMAEMA) with N‐(tert‐butoxycarbonyl)aminoethyl methacrylate (Boc‐AEMA) or N‐(tert‐butoxycarbonyl)aminohexyl methacrylate (Boc‐AHMA) followed by acid deprotection. Gel permeation chromatography (GPC) measurements revealed that Boc‐protected methacrylate copolymers had M_n in the range of 16.1–23.0 kDa and low polydispersities of 1.12–1.26. The copolymer compositions were well controlled by monomer feed ratios. Dynamic light scattering and agarose gel electrophoresis measurements demonstrated that these PDMAEMA copolymers had better DNA condensation than PDMAEMA homopolymer. The polyplexes of these copolymers revealed low cytotoxicity at an N/P ratio of 3/1. The in vitro transfection in COS‐7 cells in serum free medium demonstrated significantly enhanced (up to 24‐fold) transfection efficiencies of PDMAEMA copolymer polyplexes as compared with PDMAEMA control. In the presence of 10% serum, P(DMAEMA/AEMA) and P(DMAEMA/AHMA) displayed a high transfection activity comparable with or better than 25 kDa PEI. These results suggest that cationic methacrylate copolymers are highly promising for development of safe and efficient nonviral gene transfer agents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2869–2877, 2010