Rate of radical polymerization of N,N-dimethylaminoethyl methacrylate in cyclohexane

Summary Anions of propene, isobutylene and cycloheptatriene have been prepared using Lochmann's Base. Star polymers in the form of one arm star, two arm star and three arm star polymers of styrene have been synthesized from the allyl anion (2), 2-methylenepropylenyl dianion (4) and the cycloheptatrienyl trianion (6) respectively, with acid end groups by quenching the living polymers with carbon dioxide. The number average molecular weight has been determined by stoichiometry, HPSEC and end group analysis by titration.     

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     

Grafting of pH-sensitive poly (N,N-dimethylaminoethyl methacrylate-co-2-hydroxyethyl methacrylate) onto HNTS via surface-initiated atom transfer radical polymerization for controllable drug release

Copolymer brushes composed of N,N-dimethylaminoethyl methacrylate (DMAEMA) and 2-hydroxyethyl methacrylate (HEMA) were tethered on the surface of HNTs (HNTs) through surface-initiated atom transfer radical polymerization (SI-ATRP). ATRP initiator was anchored to surface and copolymers were synthesized from surface with different compositions of monomers. Successful grafting of copolymer brushes was approved by FTIR, TGA, XPS, FE-SEM, TEM, and N₂ adsorption-desorption.¹H NMR was used to determine the composition of copolymers. pH-sensitive properties of copolymer-grafted nanotubes were investigated by UV-visible absorbance in different pH values. Finally, loading and in vitro drug release from neat and copolymer-grafted HNTs were investigated using diphenhydramine hydrochloride as a model drug. Incorporation of DMAEMA to structure of polymers led to pH sensitivity of grafted-copolymers and controlled release of drug upon varying the pH of release medium. pH-dependent drug release showed that drug release was increased by decreasing pH of release medium and increasing DMAEMA content.     

Controlled radical polymerization

Summary The free radical polymerization of chloromethylstyrene (CMS) with benzoyl peroxide (BPO) as initiator and 2,2,6,6 tetramethyl-1-piperidiniloxy (Tempo) as counter radical was studied. The living character was demonstrated by the linear dependence of versus conversion like that the control with polydispersity lower than 1,5. In a second step, styrene was introduced in polychloromethylstyrene capped with Tempo to produce PCMS-b-PS block copolymers (12,000/60,000) with and PCMS-Tempo macroinitiator efficiency closed to 85%.     

Controlled radical polymerization of methyl methacrylate in the presence of 2-bromoethanol

Summary The radical polymerization of methyl methacrylate (MMA) and styrene (St) initiated by 2,2’-azobis(isobutyronitrile) (AIBN) at 60 °C in the presence of haloalkyl alcohol are studied. The influence of structure and concentration of haloalkyl alcohol as a transfer agent are investigated. For the radical polymerization of MMA in the presence of large amount of 2-bromoethanol, controlled radical polymerization is proceeded. The 2-bromoethanol is, thus, one of the transfer agents for radical polymerization to control the molecular weight and the structure of poly(MMA).     

Plasma graft polymerization of N,N-dimethylaminoethyl methacrylate and water–ethanol separation by pervaporation through the grafted membranes

N,N-dimethylaminoethyl methacrylate was graft-polymerized onto the porous polypropylene films of Celgard 2400 and 2500 which have been previously surface-activated by glow discharge plasmas. The grafting was dependent on various factors both in the plasma pretreatment and the post-polymerization with the monomer. The reaction was discussed from the aspects of the dependences of graft polymerization on discharge power, plasma pretreatment period, etc. When the grafting exceeded a critical amount depending on the size of pores on the substrate film, pervaporation of water-ethanol separation functioned through these grafted membranes. The water permselectivity was improved by the ammonium ionization of the pendant N,N-dimethylamino group using dimethyl sulfate or chloroacetic acid, although the increase of prevaporation performance was not so high as those previously obtained by the grafted poly(sodium acrylate) -type membranes. Pervaporation characteristics of these membranes were discussed from the ionized states of the permselective layers analyzed by IR and ESCA.     

Composite membranes from polyacrylonitrile with poly(N,N-dimethylaminoethyl methacrylate)-grafted silica nanoparticles as additives

Polyacrylonitrile (PAN)-based composite membranes were prepared by immersion precipitation method by using poly(N,N-dimethylaminoethyl methacrylate)-grafted silica (PDMAEMA@SiO₂) nanoparticles as hydrophilic additives. The molecular weight of PDMAEMA were controlled by the surface initiated atom transfer radical polymerization of N,N-dimethylaminoethyl methacrylate on SiO₂ nanoparticles. The synthesized nanoparticles have a typical core–shell structure as characterized in detail by FT-IR, TEM, DLS and GPC. The prepared PAN-based composite membranes have higher porosity and water permeation flux than those of the pure PAN membranes. They also show high rejection (⩾90%) to bovine serum albumin and high flux recovery ratio (⩾90%) to water permeation. These improved performances are attributed to the good hydrophilicity of PDMAEMA@SiO₂ nanoparticles. The results suggest that PDMAEMA@SiO₂ nanoparticles are suitable for the property optimization of PAN-based composite membranes.     

Controlled polymerization of 2,3,5,6-tetrafluorophenyl methacrylate

Well-defined homopolymer of 2,3,5,6-tetrafluorophenyl methacrylate (TFPM) was successfully synthesized via atom transfer radical polymerization (ATRP) technique. Controlled polymerization was achieved with the addition of CuBr₂ as deactivator, which decreased the reaction rate and minimized the premature termination. The controlled/“living” polymerization behavior was supported by kinetic studies and the full chain extension for block copolymerization with 2-(dimethylamino) ethyl methacrylate (DMAEMA). Poly(TFPM) is an useful precursor for poly(methacrylamides) library syntheses. The active ester groups reacted with a variety of amines to produce a range of well-defined poly(methacrylamides), some of which would have been difficult to obtain by direct polymerizations of the methacrylamide monomers. Complete conversion to poly(methacrylamide) was achieved with unhindered primary amines. Substitution reactions with aromatic amines such as aniline did not occur under normal reaction conditions.     

纤维素-甲基丙烯酸丁酯的原子转移自由基聚合

以2-溴异丁酰溴为溴化剂,在离子液体([Amim]Cl)中与纤维素反应制备溴化纤维素大分子引发剂,以溴化纤维素/CuBr/N,N',N',N″,N″-五甲基二乙烯基三胺(PMDETA)为引发体系,N,N-二甲基甲酰胺(DMF)为溶剂,研究了甲基丙烯酸丁酯(BMA)的原子转移自由基聚合反应(ATRP)。合成了结构明晰的以纤维素为主链,聚甲基丙烯酸丁酯为支链的接枝共聚物Cellulose-g-PBMA。通过FTIR、1HNMR和GPC分别对大分子引发剂和接枝聚合物进行了分析。考察了聚合反应的活性特征,反应时间、催化体系、溶剂对聚合物相对分子质量(简称分子量,下同)及分子量分布的影响。结果表明,聚合反应转换率随时间呈线性增加,反应过程是活性可控聚合,催化剂和溶剂分别选用PMDETA/CuBr和DMF使反应更高效。     

Atom transfer radical polymerization of lauryl methacrylate

The atom transfer radical polymerization (ATRP) of lauryl methacrylate (LMA) with an ethyl 2‐bromobutyrate/CuCl/N,N,N′,N″,N″‐pentamethyldiethylenetriamine initiation system was successfully carried out in toluene, and poly(lauryl methacrylate) with a low polydispersity (1.2 < weight‐average molecular weight/number‐average molecular weight < 1.5) was obtained. Plots of ln ([M])₀/([M]) versus time and plots of the molecular weight versus conversion showed a linear dependence, indicating a constant number of propagating species throughout the polymerization. The rate of polymerization was 0.56‐order with respect to the concentration of the initiator and 1.30‐order with respect to the concentration of the Cu(I) catalyst. In addition, the effect of the solvent on the polymerization was investigated, and the thermodynamic data and activation parameters for the solution ATRP of LMA were reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1117–1125, 2003     

Crosslinking during radical polymerization of dodecyl methacrylate

A much more efficient formation of crosslinks was observed in the free‐radical polymerization of dodecyl methacrylate with respect to the amount of decomposed peroxide than it would correspond to the additional peroxide crosslinking of formed poly(dodecyl methacrylate). Polymer crosslinking also proceeds after using 2,2´‐azoisobutyronitrile as initiator of the polymerization of dodecyl methacrylate, although with a substantially lower efficiency compared to the initiation by peroxide under comparable conditions. The efficient formation of crosslinked structures can be explained by branching and copolymerization of monomer with multifunctional dead polymer. Multifunctionality of the formed macromolecules is a result of transfer and addition reactions of the present free radicals with the formed polymer. The difference in the influence of the initiator follows from the higher reactivity of oxy radicals in transfer reactions with monomer dodecyl methacrylate which results in a greater number of polymerizable double bonds built in the polymer chain.     

Polyvinyl acetate as a template for the radical polymerization of methyl methacrylate

The template polymerization of methyl methacrylate (MMA) along with atactic polyvinyl acetate (at-PVAC, M?_v = 55880) at 60°C for 120 min in dimethyl formamide (DMF) has been measured dilatometrically to study the effects of the concentrations of template, monomer, and initiator upon the kinetics. The resulting plots of relative polymerization rate (V_R) vs. the at-PVAC- and MMA-concentration showed that in the present system the polymerization is a combination of three different reaction mechanisms, the blank reaction and two template mechanisms (I and II). The order of reaction with respect to template, monomer and initiator is 0.66, 0.75 and 0.40, respectively. Viscometric measurements showed that complexation between at-PVAC and PMMA was maximum when the template/polymer ratio was 1 : 1 and the time required for complete complexation was 10 min. The overall energy of activation was 33.5 and 25.0 kJ mol^?1 in the presence and absence of at-PVAC, respectively.     

A study of gas transport through interfacially formed poly(N,N-dimethylaminoethyl methacrylate) membranes

Gas transport through interfacially formed poly(N,N-dimethylaminoethyl methacrylate) membranes was investigated. The membrane performance for the separation of binary CO₂/N₂, CO₂/CH₄ and CO₂/H₂ mixtures was studied, and the coupling effects between the permeating species were evaluated by comparing the permeance of individual components in the mixture with their pure gas permeance. For the permeation of these binary gas mixtures, the presence of CO₂ was shown to influence the permeation of the other components (i.e., N₂, H₂ and CH₄), whereas the permeation of CO₂ was not affected by these components. In consideration that water vapor is often encountered in applications involving CO₂ separation, the presence of water vapor on the membrane permselectivity was also studied. When hydrated, the membrane was shown to be more permeable to CO₂, while the membrane selectivity did not change significantly. Unlike membranes based on size-sieving of penetrant molecules, the present membranes exploit the favorable interactions between the hydrophilic quaternary amines in the membrane and CO₂, especially in the presence of water vapor in the feed.     

Controlled synthesis of random,block-random and gradient styrene,methyl methacrylate and acrylonitrile Terpolymers via Nitroxide-mediated free radical polymerization

Different types of the styrene ? methyl methacrylate ?acrylonitrile terpolymers were synthesized according to the recently proposed concept of the living nitroxide-mediated terpolymerization. Random azeotropic and gradient terpolymers were prepared using the living TEMPO-mediated polymerization. Block random terpolymer was obtained via the living terpolymerization initiated by macro-alkoxyamine polystyrene-SG1. In all systems, terpolymerization proceeds in the living manner even in the presence of TEMPO. Upon complete polymerization at high conversions of monomers, the molecular weight of terpolymers linearly increases with the monomer conversion. The resultant terpolymers were characterized by the methods of turbidimetric titration, GPC, DSC, and TGA, and their characteristics were compared with their non-living analogs synthesized by the conventional radical polymerization. The effect of the macromolecular structure on the thermal stability of the terpolymers was studied.     

Triazolinyl-controlled radical polymerization as innovative route to poly(hydroxyethyl methacrylate)

Summary 2,2'-Azoisobutyronitril (AIBN) initiated radical polymerization of trimethylsilyloxyethyl methacrylate (TMS-HEMA) was carried out in N,N-dimethylformamide (DMF) with the triazolinyl radical (T•) as additive. The latter effected a controlled polymerization process at least up to 60 % monomer conversion. The obtained poly(TMS-HEMA) with triazolin endfunctionality was applied to polymerize styrene, resulting in the formation of poly(TMS-HEMA)-block-polystyrene. Received: 22 February 2001/Accepted: 6 March 2001     

Using poly(N,N-dimethylaminoethyl methacrylate)/polyacrylonitrile composite membranes for gas dehydration and humidification

The transport of water vapor through a composite membrane consisting of hydrophilic poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) as the active layer and polyacrylonitrile (PAN) as the substrate was investigated, and the performance of the membrane for gas dehydration and humidification applications was evaluated. For gas dehydration, methane/water vapor mixtures were used as feed and vacuum was applied on the downstream side. The feed composition and operating temperature were found to have a significant effect on the membrane performance. The PAN substrate had little effect on the permeation of methane, but the resistance of the substrate to water vapor permeation was significant because of the substantially higher permeability of water vapor in the membrane. For gas humidification, liquid water was brought to be in contact with the active layer of the membrane and nitrogen gas flowed on the other side. With an increase in the gas flow rate, the mass transfer rate of water through the membrane to reach the gas stream increased, and the humidity level of the gas stream decreased. The humidification can be enhanced significantly by operating at a higher temperature. A phenomenological mass transfer equation was derived for membrane humidifiers to correlate the overall mass transfer coefficient and membrane area, and this equation could be used in process design and scale up.     

一种CO2调控变粘聚合物合成及变粘机理分析

将甲基丙烯二甲胺基乙酯(DMAEMA)与丙烯酰胺( AM)进行水溶液原子自由基共聚,制备出一种新型粘度可控聚合物P (AM-DMAEMA)。其最佳合成条件为: 单体浓度20%,聚合温度40℃,引发剂浓度0.2 %,聚合时间4.0h。聚合物分子结构采用核磁氢谱进行表征; 通过溶液电导率、Zeta电位及粒径分析实验证实其具有CO2可逆调控性能,并对聚合物溶液粘度变化性能及变粘机理进行了研究。结果表明,P(AM-DMAEMA)水溶液具有CO2调控变粘性能和较好的CO2结合稳定性。