PAm-g-PMAA亲水性聚合物微球的合成

利用链转移自由基聚合和端基置换反应法 ,合成了苯乙烯基单封端的聚甲基丙烯酸叔丁酯 (PBMA)大分子单体 .在N ,N′ 亚甲基二丙烯酰胺 (Bis A)存在的条件下 ,使PBMA大分子单体与亲水性单体丙烯酰胺(Am)在乙醇 水的混合介质中进行分散共聚反应 ,得到了表面为PBMA接枝的聚丙烯酰胺 (PAm g PBMA)聚合物微球 .将所得PAm g PBMA微球在酸性条件下水解 ,得到了整体亲水的聚甲基丙烯酸接枝的聚丙烯酰胺(PAm g PMAA)聚合物微球 .用激光光散射、透射电子显微镜和X射线光电子能谱仪等对聚合物微球的直径、形态及表面组成进行了表征 .研究结果表明 ,在共聚反应中PBMA大分子单体的分子量与浓度、Bis A浓度和介质的组成对微球的形成与颗粒直径的大小有明显影响 ;所形成的聚合物颗粒是以PBMA为壳、以交联PAm为核的核壳结构微球 .     

自组装制备聚(丙烯酸叔丁酯-b-甲基丙烯酸二甲胺基乙酯)壳交联胶束

以1-氯代乙苯为引发剂、氯化亚铜/N,N,N′,N″,N″-五甲基二乙撑三胺(PMDETA)为催化体系、丁酮-异丙醇为混合溶剂,通过原子转移自由基聚合法制备不同分子量的大分子引发剂聚丙烯酸叔丁酯(1-PECl)及不同嵌段比的两亲性嵌段共聚物聚(丙烯酸叔丁酯-b-甲基丙烯酸二甲胺基乙酯)(P(tBA-b-DMAEMA))。通过1H-NMR表征了P(tBA-b-DMAEMA)的结构,GPC测试了其分子量及分子量分布。P(tBA-b-DMAEMA)在选择性溶剂中自组装形成核-壳结构的胶束,引用了乙烯基乙二醇二碘醚(BIEE)为交联剂与链段PDMAEMA发生化学交联反应从而得到稳定的壳交联胶束结构,并通过马尔文粒径仪研究了自组装所得胶束的温度及pH敏感性。     

机理转移法合成聚丁二烯-b-聚(甲基丙烯酸N,N-二甲氨基乙酯)两亲性嵌段共聚物

将活性负离子聚合与原子转移自由基聚合(ATRP)技术相结合,运用机理转移法制备了一种两亲性材料聚丁二烯-b-聚(甲基丙烯酸N,N-二甲氨基乙酯)(PB-b-PDMAEMA)嵌段共聚物.首先通过负离子聚合方法设计合成聚丁二烯,用环氧丙烷封端,2-溴异丁酰溴作酯化剂,合成具有活性端基溴的聚丁二烯大分子引发剂(PB-B r),再用其引发亲水性单体DMAEMA进行原子转移自由基聚合,聚合动力学证实了该聚合反应具有典型的活性/可控自由基聚合的特征.通过差示扫描量热法(DSC)研究嵌段共聚物的微相分离行为.制备的大分子引发剂及两亲性嵌段共聚物经凝胶色谱、红外和核磁表征证实了预定的结构.     

含偶氮苯两亲性ABA三嵌段共聚物合成与自组装研究

利用原子转移自由基聚合(ATRP)制备了中间链段含对氰基偶氮苯尾挂液晶基元的PMAA-b-PMAZOCN-b-PMAA两亲性三嵌段共聚物.首先合成了含有偶氮苯液晶基元的甲基丙烯酸酯单体;再使用小分子双端引发剂,以对壬基联二吡啶、溴化亚铜为催化剂,通过ATRP反应制备了含偶氮苯液晶侧基的双端大分子引发剂.进一步以氯化亚铜为催化剂,用该大分子引发剂引发甲基丙烯酸叔丁酯聚合,制备了结构规则的PtBMA-b-PMAZOCN-PtBMA三嵌段共聚物.通过在三氟乙酸作用下的选择性水解,将PtBMA段中的甲基丙烯酸叔丁酯单体单元转化为甲基丙烯酸,得到了两端亲水,中间疏水的两亲性ABA三嵌段共聚物.用1H-NMR、GPC、PLM、DSC等对产物进行了表征.并利用溶剂诱导微相分离的方法,研究了该共聚物在THF/水混合溶剂中的自组装行为.TEM结果显示,在采用的亲疏水链段比例的条件下,得到了囊泡结构.囊泡结构的平均直径在300~500 nm.在固态下经过紫外光照射,囊泡结构转变为实心胶体球.     

通过反应性单体法制备聚乙烯-接枝-聚甲基丙烯酸酯和聚乙烯-接枝-聚丙烯酸

茂金属催化剂1,1′-亚乙基双茚基二氯化锆[rac-C2H4(indenyl)2ZrCl2]-MAO催化乙烯和对-烯丙基甲苯共聚合得到的共聚物为底物进行自由基溴化反应,1H-NMR表明所得的溴化聚乙烯共聚物中对-烯丙基甲苯单元两个苄基位上各有一个氢被溴取代.以此溴化聚乙烯共聚物为大分子引发剂,以CuCl/N,N,N′,N′,N″-五甲基二乙基三胺为催化剂,分别进行了甲基丙烯酸甲酯和丙烯酸叔丁酯的原子转移自由基聚合,制备出相应的聚乙烯接枝共聚物.其中,聚乙烯接枝聚丙烯酸叔丁酯共聚物在盐酸作用下可以高效水解为聚乙烯接枝聚丙烯酸共聚物,然后在氢氧化钠作用下可以进一步转化为聚乙烯接枝聚丙烯酸钠共聚物.Mulao试验表明接枝共聚物对聚乙烯的极性具有明显的改善作用.     

基于聚亚甲基的三嵌段聚合物:合成及其多孔薄膜的制备

利用叶立德活性聚合与原子转移自由基聚合(ATRP)相结合的方法制备得到基于聚亚甲基的两、三嵌段聚合物.首先由叶立德活性聚合及氧化反应得到末端羟基的聚亚甲基(PM-OH),再与2-溴异丁酰溴反应得到含溴末端的大分子引发剂(PM-Br),之后引发丙烯酸叔丁酯的ATRP聚合得到聚亚甲基-b-聚丙烯酸叔丁酯(PM-b-P-t-...     

ATRP法合成两亲的含氟柱状刷PBIEM-g-(PAA-b-PFA)

以聚甲基丙烯酸[2-(2-溴异丁酰氧)]乙酯(PBIEM)为大分子引发剂,采用接出(grafting from)原子转移自由基聚合(ATRP)技术合成了以聚丙烯酸叔丁酯-b-聚含氟丙烯酸酯为侧链的柱状分子刷PBIEM-g-(PtBA-b-PFA).通过GPC,1H-NMR和FTIR对PBIEM-g-(PtBA-b-PFA)组成和结构进行了表征,证实ATRP过程中没有发生分子间或分子内偶合反应,制备得到可控性好的含氟嵌段共聚物刷.利用大分子链中叔丁酯基团的水解反应生成两亲的含氟柱状刷PBIEM-g-(PAA-b-PFA),原子力显微镜可直接观察到PBIEM-g-(PAA-b-PFA)特征的核壳型柱状结构,得到聚合物刷的整体长度为ln=54~72 nm.     

原子转移自由基聚合合成聚乙烯胺大分子单体及其共聚反应研究

以水为反应介质, 采用原子转移自由基聚合(ATRP), 在70 ℃下合成了末端为溴原子的聚丙烯酰胺预聚体(PAM-Br). 利用水相凝胶渗透色谱(GPC)对PAM-Br的相对分子质量和分子量分布进行了表征, 结果表明: 单体浓度、单体与引发剂物质的量之比和反应时间对PAM-Br的分子量及其分布有较大的影响, 在较低AM单体与引发剂物质的量比条件下, 其聚合过程符合ATRP的基本规律. 进而使PAM-Br预聚体末端的溴原子与甲基丙烯酸(MAA)进行亲核取代反应, 得到了末端带有不饱和双键的大分子单体(MAA-PAM). 并利用霍夫曼降解制备出了部分胺解的聚乙烯胺(MAA-PVAm)大分子单体, 其结构由傅里叶变换红外(FTIR)和核磁共振仪(NMR)的表征得到了确定. 以得到的大分子单体为反应性分散稳定剂, 与苯乙烯在乙醇/水的混合介质中进行分散共聚反应, 制得了聚苯乙烯接枝MAA-PVAm (PS-g-PVAm)复合微球, 由扫描电子显微镜(SEM)观察发现: 微球保持规整的球形结构, 粒径分布均一, 有较好的单分散性.     

PtBMA-b-P4VP的ATRP合成及其化学转变

以α-氯代丙酸乙酯(ECP)为引发剂,N,N,N′,N″,N″-五甲基二亚乙基三胺(PMDE-TA)为配体,在N,N′-二甲基甲酰胺(DMF)溶液中引发甲基丙烯酸叔丁酯(tBMA)进行原子转移自由基聚合(ATRP),调节聚合反应时间得到了端基为氯原子,数均分子量为1.8×103~6.4×103的聚甲基丙烯酸叔丁酯(PtBMA-Cl)大分子引发剂。采用合成的5,5,7,12,12,14-六甲基-1,4,8,11-四氮杂环化合物(Me6[14]aneN4)为配体,使PtBMA-Cl引发4-乙烯吡啶(4VP)进行ATRP反应,得到了PtBMA-b-P4VP两嵌段共聚物,可使P4VP的收率达到60%。通过对PtBMA-b-P4VP的不同链段进行季铵化和水解反应,得到了聚甲基丙烯酸-b-季铵化聚4-乙烯吡啶(PMAA-b-QPVPB)亲水性嵌段共聚物。傅里叶变换红外光谱(FT-IR)、核磁共振(1H-NMR)和凝胶渗透色谱(GPC)分析表明:所得嵌段共聚物的结构明确,可将PtBMA与P4VP的链段长度之比调整在1∶0.5~1∶1的范围内。     

聚甲基丙烯酸甲酯-聚甲基丙烯酸两亲性嵌段共聚物的制备及自组装形态的研究

以2-溴异丁酸乙酯为引发剂, 氯化亚铜/联二吡啶为催化剂, 通过原子转移自由基聚合(ATRP)获得分子链末端含一个α-溴原子的聚甲基丙烯酸甲酯(PMMA-Br), 以此为大分子引发剂引发甲基丙烯酸铅[Pb(MA)₂]单体进行ATRP反应, 制得P[MMA-b-Pb(MA)_2]嵌段共聚物, 将此共聚物在盐酸中进行离子交换即得聚甲基丙烯酸甲酯-聚甲基丙烯酸的两亲性嵌段共聚物[P(MMA-b-MAA)]. 用FTIR, GPC, NMR和SEM方法对共聚物进行了表征.     

Synthesis of well‐defined macromonomers by the combination of atom transfer radical polymerization and a click reaction

This article presents a new strategy for synthesizing a series of well‐defined macromonomers. Bromine‐terminated polystyrene and poly(t‐butyl acrylate) with predetermined molecular weights and narrow distributions were prepared through the atom transfer radical polymerization of styrene and t‐butyl acrylate initiated with ethyl 2‐bromoisobutyrate. Then, azido‐terminated polymers were obtained through the bromine substitution reaction with sodium azide. Catalyzed by CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine, the azido end group reacted with propargyl methacrylate via a 1,3‐dipolar cycloaddition reaction, and ω‐methacryloyl‐functionalized macromonomers were thus obtained. The end‐group transformation yields were rather high, as characterized by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectra and ¹H NMR analysis. By this effective and facile approach, some novel macromonomers that otherwise are difficult to achieve, such as poly(ethylene oxide)‐block‐polystyrene, were easily prepared. Radical homopolymerizations of these macromonomers were performed, and a series of comb polymers were prepared. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6103–6113, 2006     

Preparation of P4VP-g-PSt Copolymer Microspheres with Controllable Size by Atom Transfer Radical Polymerization Synthesized Poly(4-vinylpyridine) Macromonomer

Poly(4‐vinylpyridine) macromonomer (St‐P4VP) with a styryl end group was synthesized by atom transfer radical polymerization (ATRP) of 4‐vinylpyridine using p‐(chloromethyl)styrene (CMSt) as functional initiator, CuCl as catalyst and tris[2‐(dimethylamino)ethyl]amine (Me₆TREN) as ligand in 2‐propanol. The structure of St‐P4VP macromonomer was identified by proton nuclear magnetic resonance (¹H NMR). The result of gel permeation chromatography (GPC) illustrated that the number‐average molecular weight of St‐P4VP could be controlled by adjusting polymerization conditions. Poly(4‐vinylpyridine) grafted polystyrene microspheres (P4VP‐g‐PSt) were then prepared by dispersion copolymerization of styrene with St‐P4VP macromonomers. The effects of polymerization reaction parameters such as medium polarity, concentration of St‐P4VP macromonomer and polymerization temperature on the sizes and size distribution of P4VP‐g‐PSt microspheres were investigated. The results of transmission electron microscopy (TEM), scanning electron microscopy (SEM) and laser light scattering (LLS) indicated that mono‐dispersed P4VP‐g‐PSt microspheres with average diameters of 100–200 nm could be obtained when the molar ratio of St to St‐P4VP was 0.25:100 in ethanol/water mixed solvents (V/V=80:20) at 60°C. Such kind of graft copolymer microspheres was expected to be applied to many fields such as drug delivery system and protein adsorption/separation system due to their particular structure.     

Preparation of Fluorescent Polystyrene via ATRP with Dimethylamino Chalcones as Initiator

4‐(3‐(4‐(Dimethylamino)phenyl)acryloyl)phenyl‐2‐bromo‐2‐methylpropanoate (APPBr) was used for the heterogeneous atom transfer radical polymerization (ATRP) of styrene (St) with copper(I) bromide/N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine (PMDETA) catalytic system. The functional end group was characterized via UV‐Vis and ¹H NMR spectra. The polymerization showed a first‐order kinetic characteristic and each of the obtained polymers had well‐controlled molecular weight and relatively low polydispersity index (PDI). Furthermore, the obtained end‐functionalized polystyrene (PS) in solution showed strong green‐light emission which is further affected by mixing different metal cations. In particular, the fluorescent intensity of the polymer was decreased in the presence of Ag⁺, Cu²⁺ and Fe³⁺.     

Atom Transfer Radical Polymerization of Styrene with 5‐Chloromethyl‐2‐hydroxy‐benzaldehyde as Initiator

Abstract

Atom transfer radical polymerization (ATRP) of styrene (St) proceeded using 5‐chloromethyl‐2‐hydroxy‐benzaldehyde as initiator, CuCl as catalyst, and N,N,N′,N′,N′‐pentamethyldiethyltriamine (PMDETA) as ligand. The results show that the polymerization is a first order reaction with respect to monomer concentration. The polymerization displayed living character as evidenced by a liner increase of monomer weight with conversation and a relatively narrow distribution (M _n/M _w ranges from 1.25 to 1.50). The end structure of PSt was analyzed by ¹H‐NMR, and PSt initiated MMA to form block copolymer (PSt‐b‐PMMA), which also proved that the polymerization could be controlled. The effects of reaction temperature and monomer to initiator mole ratio on the polymerization displayed living character were discussed.     

Controlling the formation of long‐subchain hyperbranched polystyrene from seesaw‐type AB2 macromonomers: Solvent polarity and solubility

Through atom transfer radical polymerization of styrene with 1,3‐dibromomethyl‐5‐propargyloxy‐benzene as initiator followed by the conversion of bromine end‐groups into azide end‐groups, well‐defined seesaw‐type polystyrene (PSt) macromonomers with two molecular weights (M_n = 8.0 and 28.0 k) were obtained. Thus, a series of long‐subchain hyperbranched (lsc‐hp) PSt with high overall molar masses and regular subchain lengths were obtained via copper‐catalyzed azide–alkyne cycloaddition click chemistry performed in THF and DMF, respectively. The polycondensation of seesaw‐type macromonomers was monitored by gel permeation chromatography. Because DMF is the reaction medium with higher polarity, click reaction proceeds more easily in DMF. Therefore, the growth of lsc‐hp PSt in DMF has faster rate than that in THF for the shorter seesaw‐type macromonomer (Seesaw‐8k). However, THF is the solvent with better solubility to PSt and leads to looser conformation of PSt chains. Thus, for the longer seesaw macromonomer (Seesaw‐28k), lsc‐hp PSt in THF has higher overall molar mass. As well, the self‐cyclization of seesaw‐type macromonomers also depends on both solvent and molar mass of macromonomer. The self‐cyclization degrees of Seesaw‐8k in DMF and THF are almost the same while that of Seesaw‐28k macromonomer is obviously lower in THF. The experimental results suggest a physical consideration to control the growth of hyperbranched polymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

CuBr2/N,N,N′,N′‐Tetra[(2‐pyridal)methyl]ethylenediamine/Tertiary Amine as a Highly Active and Versatile Catalyst for Atom‐Transfer Radical Polymerization via Activator Generated by Electron Transfer

Summary: A highly active and versatile CuBr₂/N,N,N′,N′‐tetra[(2‐pyridal)methyl]ethylenediamine (CuBr₂/TPEN)‐tertiary amine catalyst system has been developed for atom transfer radical polymerization via activator‐generated‐by‐electron‐transfer (AGET ATRP). The catalyst mediates good control of the AGET ATRPs of methyl acrylate, methyl methacrylate, and styrene at 1 mol‐% catalyst relative to initiator. A mechanism study shows that tertiary amines such as triethylamine reduces the CuBr₂/TPEN complex to CuBr/TPEN.

The GPC traces of PSt, PMA, and PMMA prepared by AGET ATRP at 1 mol‐% of catalyst relative to initiator are monomodal and have low polydispersities.     

原子转移自由基聚合原位合成温敏性微球

以过硫酸钾为引发剂、丙酮-水[V(丙酮)∶V(水)＝4∶6]的混合溶剂为反应介质, 在少量二乙烯苯存在的条件下使苯乙烯(St)和对氯甲基苯乙烯(CMSt)进行无皂乳液共聚反应, 得到了粒径大小均匀的交联型聚苯乙烯(PSt)微球, 由X射线光电子能谱对表面组分测定发现: CMSt上的氯原子在聚合过程中富集于交联微球的表面. 以此交联型PSt微球为原子转移自由基聚合(ATRP)的引发剂, 在22 ℃下引发N-异丙基丙烯酰胺(NIPAAm)进行原位ATRP反应, 得到了表面原子转移自由基聚合接枝的交联聚苯乙烯(PNIPAAm-g-PSt)温敏性微球. 借助傅立叶变换红外光谱、差示扫描量热仪、扫描电子显微镜及激光光散射仪等对PNIPAAm-g-PSt的结构、相转变温度、形态及不同温度下的粒径变化进行了测定, 结果表明NIPAAm单体成功地原位ATRP接枝在交联PSt微球的表面, 接枝微球的球形更规整, 在水中的相转变温度约为32 ℃, 具有明显的温度敏感性.     

Synthesis of nanocylinders consisting of graft block copolymers by the photo‐induced ATRP technique

Photoinduced atom transfer radical polymerizations (ATRP) of t‐butyl methacrylate (BMA) were carried out, initiated by model initiator benzyl N,N‐diethyldithiocarbamate (BDC) in the presence of CuCl/bipyridine (bpy) under UV irradiation. We performed the first‐order time‐conversion plots in this polymerization system, and the straight line in the semilogarithmic coordinates indicated a first‐order in the monomer. The molecular weight of poly(t‐butyl methacrylate) (PBMA) increased in direct proportion to monomer conversion. The molecular weight distribution (M_w/M_n) of PBMA was about 1.3. The initiator efficiency, f, was close to 1.0, which indicated that no side reactions occurred. A copper complex, CuCl/bpy, reversibly activated the dormant polymer chains via a N,N‐diethyldithiocarbamate (DC) transfer reaction such as Cu(DC)Cl/bpy, and it was dynamic equilibrium that was responsible for the controlled behavior of the polymerization of BMA. On the basis of this information, we established a preparation method of nanocylinders consisting of graft block copolymers by grafting from photoinduced ATRP of multifunctional polystyrene having DC pendant groups with vinyl monomers [first monomer, BMA; second monomer, styrene or methyl methcrylate (MMA)]. We have carried out the characterization of such nanocylinders in detail. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 63–70, 2005     

End‐functionalized polystyrene by ATRP: A facile approach to primary amino and carboxylic acid terminal groups

Monoamino‐terminated and monocarboxylic acid‐terminated polystyrenes containing active halogenated end groups were prepared by atom transfer radical polymerization (ATRP) using the so‐called initiator method and protective group chemistry. α‐Chloropropionates were synthesized and utilized as initiators containing the tert‐butoxycarbonyl (t‐BOC)‐protected amino and the tert‐butyl (t‐Bu)‐protected carboxylic acid function, respectively. Optimum polymerization conditions were attained using CuCl/N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine (PMDETA) as catalyst and 10 vol % n‐butanol as homogenizing agent at 110 °C. However, targeting larger quantities an alternative route was established employing 50 vol % N,N‐dimethylformamide (DMF). Subsequent hydrolysis of the ω‐tert‐butoxycarbonyl polystyrenes afforded well‐defined polymers with quantitative deprotection of the functional groups. Comparatively, thermolytic cleavage of the protective sites was studied. ¹H NMR verified the quantitative removal of the t‐BOC‐protecting groups. Furthermore, the resulting α‐amino‐ω‐chloro polystyrenes were reacted with Sanger reagent to confirm the existence of the thereby converted primary amino groups. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3845–3859, 2009