无机盐对PDMAEMA温度响应性能的影响

采用可逆加成-断裂链转移(RAFT)自由基聚合合成了聚甲基丙烯酸-N,N-二甲氨基乙酯(PDMAEMA),用核磁共振氢谱(~1H NMR)和凝胶渗透色谱(GPC)对其结构进行了表征。通过浊度法研究了NaCl、NaBr、KI、NaHCO_3、NH_4Cl五种无机盐对PDMAEMA水溶液低临界溶液温度(LCST)的影响,结果表明,NaCl、NaBr、KI、NaHCO_3均使溶液的LCST有不同程度下降,加入NH_4Cl使LCST现象消失。     

聚(甲基丙烯酸N,N-二甲氨基乙酯/丙烯酸2-乙基己酯)的温度及pH敏感性能的研究

采用紫外光引发光聚合得到了聚甲基丙烯酸N ,N 二甲氨基乙酯〔P(DMAEMA)〕均聚物和不同组成的聚甲基丙烯酸N ,N 二甲氨基乙酯 /丙烯酸 2 乙基己酯〔P(DMAEMA/EHA)〕共聚物。傅立叶红外光谱和核磁共振氢谱测定了P(DMAEMA/EHA)共聚物的链结构 ,结果表明 :聚合的投料比与所得产物的实际组成比一致。在 pH >8,P(DMAEMA/EHA)共聚物溶液的低临界溶液温度 (LCST)随聚合物中EHA组分的增加逐渐下降 ;在pH≤ 8时 ,则观测不到体系的LCST。 37℃下均聚物及共聚物试样 (D、D/E1、D/E2、D/E3)的pH敏感点分别为8 80 ,8 72 ,8 37,8 2 9。共聚物结构中EHA组分越多 ,则 pH敏感点越低。P(DMAEMA)均聚和共聚物的LCST随着NaCl浓度的升高而线性下降 ,且下降的速率相等。     

pH、温度和光三重敏感的PDMAEMA-AZO的研究

在含偶氮苯的三硫酯链转移剂（CTA-AZO）存在下，将甲基丙烯酸二甲氨基乙酯（DMAEMA）通过可逆加成断裂链转移（RAFT）聚合，制备了pH、温度和光三重敏感的含偶氮苯端基的聚甲基丙烯酸二甲氨基乙酯聚合物（PDMAEMA-AZO）。采用紫外光谱（UV）、红外光谱（FTIR）、核磁共振氢谱（1HNMR）和凝胶渗透色谱（GPC）对PDMAEMA-AZO的结构进行了表征，并考察了聚合物的光敏性、温敏性和pH敏感性。GPC结果表明，PDMAEMA-AZO的相对分子质量可控，且相对分子质量分布（PDI）小于1.78。PDMAEMA-AZO在不同溶剂中（氯仿、乙醇和水）的光敏性实验结果显示，该聚合物在氯仿、乙醇和水中均能够快速进行可逆光致顺反异构反应，在紫外与可见光的交替照射下，快速达到光稳态。PDMAEMA-AZO的温敏性实验表明，与聚甲基丙烯酸二甲氨基乙酯（PDMAEMA）相比，PDMAEMA-AZO的低临界溶解温度（LCST）更低。随着聚合物浓度的增加，其LCST降低，且相变窗口变窄。当pH超过9.44时，该聚合物的LCST保持不变，pH由9.44下降到7.34时，LCST升高，pH＜7.34时不再具有温敏性，说明该类聚合物是一种pH控制的具备LCST的温敏性聚合物。在紫外与可见光交替照射下，PDMAEMA-AZO 的LCST 表现为可逆的升高和降低，表明聚合物PDMAEMA-AZO具备光控温敏性。     

甲基丙烯酸二甲氨基乙酯的ATRP聚合

2-溴代异丁酸-Ⅳ-丁二酰亚胺酯（NHS—BIBA酯）由2-溴代异丁酸和,v-羟基丁二酰亚胺通过酯化反应制得。以它为引发剂,2,2＇-联吡啶（bpy）／CuBr为催化体系、水为溶剂,采用原子转移自由基聚合（ATRP）合成了带有功能基团的聚甲基丙烯酸二甲氨基乙酯（PDMAEMA）高分子。研究了引发剂、温度、反应时间、pH值和浓度对聚合产率的影响,利用凝胶渗透色谱（GPC）和核磁共振（1HNMR）测定了聚合物的分子量、多分散指数（PDI）和链结构。由GPC可知在最高产率下,Mn和Mw／Mn分别为8674和1．59,结果表明,NHS-BIBA酯引发的PDMAEMA实际数均分子量高于理论分子量,并具有低分散度,链结构上氢原子出峰符合特有的化学位移。     

紫外光引发甲基丙烯酸-N,N-二甲氨基乙酯溶液聚合的研究

研究了甲基丙烯酸 -N ,N -二甲氨基乙酯的紫外光引发自由基溶液聚合的条件 ,包括引发剂安息香乙醚用量、单体浓度、光引发时间及其对聚合速率、产率与相对分子质量的影响 ,实验确定了制备线型聚甲基丙烯酸 -N ,N -二甲氨基乙酯聚合物的工艺及方法。采用膨胀计法研究了聚合反应 ,其反应速率与单体浓度呈 1.91级关系 ,结果表明 ,单体可能同时参与了光引发过程     

RAFT合成pH和温度响应的双亲水嵌段共聚物

以S-十二烷基-S-′(2-羧基-异丙基)三硫酯(DDATC)为链转移剂,偶氮二异丁腈(AIBN)为引发剂,通过可逆加成-断裂链转移(RAFT)聚合合成了结构明确,窄相对分子质量分布(Mw/Mn=1.27)的聚(N-异丙基丙烯酰胺)-b-聚(N,N-二甲氨基甲基丙烯酸乙酯)(PNIPAm-b-PDMAEMA)双亲水两嵌段共聚物。共聚物的结构通过红外光谱、核磁共振氢谱和凝胶渗透色谱表征。采用透光率法、稳态荧光光谱法、电位滴定和动态光散射考察了PNIPAm-b-PDMAEMA在水中对温度和pH敏感的胶束化行为。结果表明,PNIPAm-b-PDMAEMA具有温度响应性,其水溶液的低临界溶液温度(LCST)为32.3℃,溶液温度高于LCST后发生温度诱导的胶束化,胶束的流体力学半径(Rh)为50 nm左右,Rh随温度升高而稍微增大;PNIPAm-b-PDMAEMA水溶液表现出明显的pH敏感性,25℃时两嵌段共聚物pH诱导胶束化的临界pH=9.8,溶液pH高于临界pH后发生pH诱导的胶束化,胶束的Rh约为31 nm(pH=11.0)。     

原子转移自由基聚合法合成阳离子星型聚合物

β-环糊精(β-CD)经2-溴异丁酰溴酰化后合成具有多个支链的引发剂2-溴异丁酰化β-环糊精(β-CD-BIBB)。然后以丙烯酰胺(AM)和甲基丙烯酸二甲氨基乙酯(DMAEMA)为共聚单体,β-CD-BIBB为引发剂,2,2'-联吡啶(BPY)为配位剂和CuBr为催化剂,采用原子转移自由基聚合(ATRP)技术合成阳离子星型聚合物。反应温度为80℃,BPY与CuBr摩尔比一定时,聚合物的黏均相对分子质量(简称黏均分子量,下同)随着DMAEMA与β-CD-BIBB摩尔比增加而升高;在DMAEMA与β-CD-BIBB摩尔比一定时,黏均分子量随着BPY与CuBr摩尔比的增加而升高。通过FTIR、1HNMR、DSC、TG等对β-CD-BIBB和阳离子星型聚合物的结构进行了表征。     

ATRP法合成低摩尔质量BPS的研究

采用ATRP法合成了一系列摩尔质量低（Mn=5×10^3～1×10^4g／mol）、分布窄（Mw／Mn=1．8～2．2）的聚苯乙烯（PS）,通过均相催化溴化法制得一系列摩尔质量低、分布窄、溴含量不同的溴化聚苯乙烯（BPS）,其中溴的质量分数最高可达75．59％,热分解温度达396℃。     

聚甲基丙烯酸/丙烯酰胺pH敏感凝胶的合成与溶胀行为研究

以单体丙烯酰胺(AM)、甲基丙烯酸(MAA),交联剂N-N'亚甲基双丙酰胺(BIS)为原料,通过自由基共聚合成了聚甲基丙烯酸/丙烯酰胺[P(MAA-co-AM)]水凝胶.研究了干凝胶在不同pH溶液中的溶胀动力学,结果表明不同AM、MAA单体配比的凝胶溶胀性具有很大差异,其溶胀率都随着溶液的pH增加而增大,在pH=12和pH=2溶液反复变换时显示可逆溶胀-退溶胀和快速响应特性,溶胀-退溶胀过程中搅拌作用对凝胶响应速率有显著影响.吸水平衡P(MAA-co-AM)水凝胶在酸性及碱性条件下均出现收缩,在pH=2下10 min之内凝胶收缩90%以上,随着pH增大逐渐减慢.通过不同浓度的NaCl与CaCl2溶液研究了溶液离子强度以及反离子的电荷数对凝胶溶胀性影响,在NaCl溶液和水中,呈现反复溶胀-退溶胀响应特性.     

BMA-DMAEMA复合基光/湿双固化聚氨酯热熔胶的合成与性能研究

以PCLT(聚己内酯三元醇)、IPDI(异佛尔酮二异氰酸酯)、i-BMA(甲基丙烯酸异丁酯)和DMAEMA(甲基丙烯酸-2-N,N-二甲氨基乙酯)等为原料,制备了BMA-DMAEMA复合基光/湿双固化PUHMA(聚氨酯热熔胶)。研究结果表明:当m(BMA)∶m(DMAEMA)=2∶3、反应温度为140℃和w(引发剂)=3.0%(相对于HMA质量而言)时,所得PU-HMA结构稳定、黏度适宜、固化完全且性能优良(剪切强度为0.176 MPa、柔韧性为5.6 mm、黏度为178 s、附着力为4级和耐水性超过100 h)。     

Synthesis of well‐defined comb‐like amphiphilic copolymers with protonizable units in the pendent chains: 2. Poly(2‐(dimethylamino)ethyl methacrylate) grafted poly(methyl methacrylate‐co‐2‐hydroxyethyl methacrylate) copolymers and their association behavior in aqueous solution

Narrow‐distribution, well‐defined comb‐like amphiphilic copolymers are reported in this work. The copolymers are composed of poly(methyl methacrylate‐co‐2‐hydroxyethyl methacrylate) (P(MMA‐co‐HEMA)) as the backbones and poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA) as the grafted chains, with the copolymer backbones being synthesized via atom‐transfer radical polymerization (ATRP) and the grafted chains by oxyanionic polymerization. The copolymers were characterized by gel permeation chromatography (GPC), Fourier‐transform infrared (FT‐IR) spectroscopy and ¹H NMR spectroscopy. The aggregation behavior in aqueous solutions of the comb‐like amphiphilic copolymers was also investigated. ¹H NMR spectroscopic and surface tension measurements all indicated that the copolymers could form micelles in aqueous solutions and they possessed high surface activity. The results of dynamic light scattering (DLS) and scanning electron microscopy (SEM) investigations showed that the hydrodynamic diameters of the comb‐like amphiphilic copolymer aggregates increased with dilution. Because of the protonizable properties of the graft chains, the surface activity properties and micellar state can be easily modulated by variations in pH. Copyright © 2004 Society of Chemical Industry     

原子转移自由基聚合在响应型聚合物中的应用

分别对原子转移自由基聚合和pH/温度响应型两亲性聚合物两者进行了综述,分析总结了利用原子转移自由基聚合制备pH/温度响应型聚合物方面的应用情况,并对其前景作了一定的展望。     

Preparation of well-defined environmentally responsive polymer brushes on monolithic surface by two-step atom transfer radical polymerization method for HPLC

Well-defined poly (2-(dimethylamino) ethyl methacrylate) (PDMAEMA) brushes were successfully prepared on the monolithic surface via two-step atom transfer radical polymerization (ATRP). The polymer brushes synthesized by the second-step ATRP were based on the active bromic groups resulting from poly (ethylene glycol dimethacrylate) (pEDMA) monolith which was prepared at room temperature by the first-step ATRP. Element analysis was used to monitor the grafting process at different reaction times. Each step of preparation was characterized by scanning electron microscope, infrared spectrum and mercury intrusion porosimetry. Employment of PDMAEMA grafted monolith as the stationary phase for chromatographic analysis of steroids demonstrated that the PDMAEMA brushes possessed both pH- and salt-responsive properties. Noticeably, it has been found that the chain length of PDMAEMA brushes could influence the retention behavior of steroids due to the controllability of ATRP, which proposed an interesting alternative to modulate retention in HPLC. This is the first application of PDMAEMA brushes grafted monolith by two-step ATRP method for constructing responsive surface in HPLC and it might exploit a new path for widening the monolith application in various fields.     

Synthesis,characterization, and property of end-functionalized telechelic PST via ATRP

Polystyrene incorporating carboxylate group as α-end was synthesized by using initiator 4-chloromethyl benzoic acid via atom transfer radical polymerization. Its ω-chlorine end-group was transformed by cumic acid, diethyl malonate, and thiol, respectively, to form end-functionalized telechelic polystyrenes. These PSts with different functionalized ω-end group (PSt 1 , PSt 2 , and PSt 3) were obtained and characterized by H NMR and TGA. This type of end-functionalized telechelic polymers can further act as polymeric ligands to form polymeric metal complexes. In this study, PSt 1 with carboxylate group at each end was allowed to react with Eu(DBM)₂Cl·2H₂O to afford a new polymeric complex PSt 1 -Eu(III) showing significant red-light emission. Moreover, the film of PSt 1 -Eu shows similar emission pattern with its DMF solution. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Two‐component “Onionlike” micelles with a PPO core,a PDMAEMA shell and a PEO corona: formation and crosslinking

BACKGROUND: Chemical or physical crosslinking of supramolecular assemblies gives them stability in a wide range of environments. Much attention is paid to multilayer (onion‐like) polymeric micelles because their functionality is higher than classic core‐shell micelles. This work reports on the formation and crosslinking of onion‐like micelles prepared by mixing two different block copolymers containing a crosslinkable poly(dimethylaminoethyl methacrylate) (PDMAEMA) block. RESULTS: Block copolymers of a crosslinkable PDMAEMA block were synthesized by atom transfer radical polymerization of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) from poly(propylene oxide) (PPO) or poly(ethylene oxide) (PEO) macroinitiators. The (PDMAEMA₁₃)‐block‐PPO₆₉‐block‐(PDMAEMA₁₃) triblock formed wormlike core‐shell micelles, which were converted into ellipsoidal onion‐like micelles on mixing with the PEO₄₅‐block‐P(DMAEMA₈‐co‐MMA₄) diblock. Onion‐like micelles were crosslinked by quaternization of DMAEMA units. CONCLUSION: Formation of onion‐like micelles by mixing two different AB (ABA) and B′C block copolymers and their subsequent crosslinking is a valuable approach towards stabilized supramolecular assemblies of a higher complexity and functionality than the individual constitutive components. Copyright © 2008 Society of Chemical Industry     

Synthesis and aqueous solution characterization of amphiphilic diblock copolymers containing carbazole

A series of near-monodisperse diblock copolymers of 2-(N-carbazolyl)ethyl methacrylate and 2-(dimethylamino)ethyl methacrylate (DMAEMA) of relatively low molecular weights (2600-24,000 g mol⁻¹) were synthesized by group transfer polymerization using tetrahydrofuran (THF) as a solvent. The molecular weight distributions and compositions of all the copolymers were obtained using gel permeation chromatography (GPC) in THF and proton nuclear magnetic resonance (¹H NMR) spectroscopy, respectively. Differential scanning calorimetry and thermal gravimetric analysis provided low glass transition temperatures (T_gs) of about 60 °C and decomposition temperatures between 320 and 450 °C for the copolymers, respectively. The three copolymers with the highest DMAEMA content were water-soluble below pH 7. Aqueous GPC at pH 3 showed that the water-soluble block copolymers formed micelles with apparent number average molecular weights above 100,000 g mol⁻¹.     

原子转移自由基聚合法合成PS-g-PMMA

以氯乙酰化聚苯乙烯微球（PS-acyl-Cl）为大分子引发剂,甲基丙烯酸甲酯（MMA）为单体,CuCl/CuCl₂及N,N,N′,N′-四甲基乙二胺（TMEDA）为催化体系的原子转移自由基聚合反应,成功在PS-acyl-Cl表面接枝上PMMA分子链而获得聚苯乙烯 接枝 聚甲基丙烯酸甲酯（PS-g-PMMA）。考察了催化剂、反应温度、溶剂用量等条件对接枝反应的影响,优化的反应条件下,使用氯乙酰基担载量3.44 mmol.g^-1的PS-acyl-Cl,15 h可获得增重率687% 的PS-g-PMMA,且反应表现出一级动力学特征（k=513×10^-5 s^-1）。通过改变反应条件,可得到不同PMMA接枝链长的PS-g-PMMA。反应得到的PS-g-PMMA经水解后有望作为高担载量弱酸型离子交换树脂或进一步功能化后作为酶的柔性固定化载体。     

Synthesis of NR‐g‐PMMA by “grafting from” method using ATRP process

Grafting poly(methyl methacrylate) or PMMA from natural rubber (NR) using ATRP process, NR has to be transformed into bromoalkyl‐functionalized NR (NRBr) acting as ATRP macroinitiator. The NRBr was prepared by two‐step chemical modification i.e., epoxidation and epoxide ring opening reaction using a nucleophile containing bromine atom such as 2‐bromopropionic acid ( A1 ) and 2‐bromo‐2‐methylpropionic acid ( A2 ). The fixation of A1 and A2 on 4‐methyl‐4‐octene, a model representing one repeat unit of NR, modified by epoxidation was prior studied and it was found that the resulting addition products from A2 using as ATRP initiator for MMA gave a better control of M _n,exp and low PDI of PMMA than that from A1 . Then, the NR was transformed into ATRP rubber macroinitiator via epoxidation, followed by epoxide ring addition with only A2 . ¹H NMR was employed to determine the amount of A2 addition units on NR, which is considered to be the same amount of grafting sites for ATRP of MMA. The grafting of PMMA was then successfully carried out from the NR backbone by ATRP process. The PMMA grafts of the NR‐g‐PMMA were indeed linked to the NR backbone via ester linkage of the A2 unit. The PMMA grafts could be cleaved from the NR backbone by acid hydrolysis, while PMMA grafting by other conventional radical reaction could not be done. Then, the average MW of PMMA grafts after separation using acetone extraction was evaluated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of thermoresponsive poly(N-isopropylmethacrylamide) and poly(acrylic acid) block copolymers via post-functionalization of poly(N-methacryloxysuccinimide)

Polymers exhibiting a thermoresponsive, lower critical solution temperature (LCST) phase transition have proven to be useful for many applications as “smart” or “intelligent” materials. A series of poly(N-isopropylmethacrylamide) (PNIPMAM) polymer, poly(N-isopropylmethacrylamide)-b-poly(acrylic acid) (PNIPMAM-b-PAA) diblock, and poly(acrylic acid)-b-poly(N-isopropylmethacrylamide)-b-poly(acrylic acid) (PAA-b-PNIPMAM-b-AA) triblock copolymer samples were synthesized via ATRP. A facile post-functionalization route was developed that uses an activated ester functionality to convert poly(N-methacryloxysuccinimide) (PMASI) blocks to LCST capable polyacrylamide, while poly(t-butyl acrylate) (PtBA) blocks were converted to water-soluble poly(acrylic acid) (PAA). The post-functionalization was monitored via ¹H NMR and ATR-FTIR. The aqueous solution properties were explored and the PNIPMAM polymers were shown to have a LCST phase transition varying from 35 to 60 °C. The ability to synthesize block copolymers that are thermoresponsive and water-soluble will be of great benefit for broader applications in drug delivery, bioengineering, and nanotechnology.