A Transformable and Bulky Methacrylate Monomer That Enables the Synthesis of an MMA-nBA Alternating Copolymer: Sequence-Dependent Self-Healing Properties

In this study, we designed a methacrylate molecule with an alkyl-substituted trichloro salicylic acid pendant as a transformable bulky monomer to enable the synthesis of an alternating copolymer of methyl methacrylate (MMA) and n-butyl acrylate (nBA). The adamantyl-substituted methacrylate monomer ( 1-Ad ) showed very low homopolymerization propensity in radical polymerizations, but afforded the alternating copolymer with nBA via copolymerization. The 1-Ad units in the resultant copolymer were quantitatively and selectively transformed into MMA via transesterification with methanol to yield the alternating copolymer of MMA and nBA. Its alternating sequence was clearly demonstrated by a structural analysis via ¹³C NMR spectroscopy as well as the low reactivity ratios for the 1-Ad and nBA pair. Finally, we verified the superior self-healing ability of the alternating copolymer compared to that of the corresponding 1 : 1 statistical copolymer.     

交替共聚物的嵌段聚合物的合成与表征

以Mn_2(CO)_(10)—CBr_4为引发剂,在AlEt_(1.5) Cl_(1.5)存在下,合成了交替共聚物的嵌段聚合物,Poly[(St-a-MA)-b-(IP-a-MMA)-b-(St-a-MA)]。NMR研究表明该嵌段聚合物各段都具有交替结构。扭辫法测定动态力学性能显示有两个T_g,分别为38℃和75℃。透射电镜研究表明,该聚合物具有两相结构。微区随硬段分子量增大而增大。     

Copolymerization of Styrene with N—phenylmaleimide by Rare Earth Coordination Catalysts

Copolymerization of styrene (St) with N-phenylmaleimide(NPMI) was studied with rare earth coordination catalyst Nd(naph)3-AlEts in toluene. Characterization of the copolymers showed that the copolymers possess an alternating structure.     

N-苯基马来酰亚胺与环己烯共聚物的制备和表征

Ｎ苯基马来酰亚胺（ＰＨＭＩ）是一种很有应用价值的共聚单体,它能赋予共聚物很好的耐热性．有关ＰＨＭＩ与甲基丙烯酸甲酯、苯乙烯及乙烯基醚的二元共聚合反应已有文献报道［１～３］．而有关ＰＨＭＩ与环烯烃特别是环己烯的共聚合研究除我们所做的工作外［４］,报道甚少．作者研究了ＰＨＭＩ与环己烯在溶液中的二元共聚合反应,并对所得的共聚物进行了表征．１　原料ＰＨＭＩ,自制,ｍ．ｐ．８８－７℃;元素分析Ｃ,６９－３３;Ｈ,４－０７;Ｎ,８－１０;理论值Ｃ,６９－３６;Ｈ,４－０７;Ｎ,８－０９,１ＨＮＭＲ（δ）…     

FREE RADICAL COPOLYMERIZATION AND KINETIC TREATMENT OF CYCLOHEXENE WITH N-PHENYLMALEIMIDE

The copolymerization of cyclohexene (M₁) and N-phenylmaleimide (M₂) in chloroform with 2,2'-azo-bis(isobutyronitrile) as an initiator was investigated. The copolymerization of N-phenylmaleimide with cyclohexene in chloroform proceeded in a homogeneous system to give an alternating copolymer over a wide range of the comonomer composition in the feed. The kinetic parameters, such as reactivity ratio, overall activity energy and the effect of comonomer composition on the initial copolymerization rate (R_p) were determined. The bimolecular termination of the copolymerization was proved. A kinetic treatment based on the model of mechanism was proposed and used to test the copolymerization of cyclohexene and N-phenylmaleimide and to quantitatively estimate the k₂₁/k₁₂ value.     

Synthesis and Properties of a Novel Diverting Agent Derived From the Copolymerization of Acrylamide with Sodium Acrylate

A novel diverting agent, which derived from the copolymer of poly(acrylamide-co-sodium acrylate) [P(AM-co-SA)], was synthesized by using aluminium nitrate [Al(NO₃)₃] as crosslinker, L-ascorbic acid/peroxide hydrogen [Vc/H₂O₂] as initiator, and methanol as temperature regulator. Thereafter, as key investigation points, the aging time and water absorbency of the resulting diverting agent were recruited, the amount of crosslinker and initiator, the ratios between acrylic acid and acrylamide, the neutralization of acrylic acid, the feeding ratios of methanol, the temperature and the reaction time were investigated. The dependency relationship between the water absorbency and aging time on each factor was also obtained.     

甲基丙烯酸缩水甘油酯与甲基丙烯酸氯乙酯共聚反应竞聚率的研究

本文合成了甲基丙烯酸缩水甘油酯、甲基丙烯酸氯乙酯和甲基丙烯酸缩水甘油酯与甲基丙烯酸氯乙酯共聚物。用~1H-NMR谱仪测定了共聚物中两种单体的含量。用Fineman-Ross和Kelen-Tilds两种作图方法以及最小二乘法对单体的竞聚率进行估假。结果表明了甲基丙烯酸氯乙酯的竞聚率(r_1)和甲基丙烯酸缩水甘油酯的竞聚率(r_2)分别为r_1=0.712,r_2=1.081。     

二乙基二烯丙基氯化铵与丙烯酰胺、丙烯酸共聚竞聚率

二乙基二烯丙基氯化铵;丙烯酰胺;丙烯酸;共聚合;竞聚率     

SalenAl(OiPr)催化CO2与氧化环己烯共聚及影响因素研究

以SalenAl(OiPr)为催化剂,分别加入各种路易斯碱作为共催化剂催化二氧化碳与氧化环己烯共聚,发现共聚催化效率与共催化剂的供电子能力有关.分别研究催化剂浓度、共催化剂的用量、反应时间、反应温度、CO2压力等各种因素对该共聚反应的影响,发现SalenAl(OiPr)浓度为2 g/L时,以等摩尔量的二甲氨基吡啶(DMAP)作为共催化剂,在4 MPa的CO2和80℃下反应32 h,可得到碳酸酯键含量>99%的共聚产物,其催化效率高达495 g/g,13C-NMR检测表明共聚物为无规立构聚合物,GPC测得分子量Mn为55900,分子量分布比较窄(PDI=1.32).DSC得到共聚物的玻璃化转变温度为136℃,热重分析(TGA)可以看出共聚物在350℃可完全分解,具有优良的热分解性.     

甲基丙烯酸甲酯与1-(2-叔丁基过氧异丙基)-3-异丙烯基苯的共聚研究

讨论了甲基丙烯酸甲酯与１－（２－叔丁基过氧异丙基）－３－异丙烯基苯的共聚行为。通过自由基共聚得到了带过氧侧基的聚合物。通过红外光谱，紫外光谱和凝胶色谱对共聚物进行了表征。用碘量法测定了共聚物中活性氧的含量，并由此测定了两者的竞聚率，ｒＤ１２０＝０．６９±０．０８，ｒＭＭＡ＝０．６３±０．０８。     

A General Strategy To Access Alternating Styrene/Substituted Styrene Copolymers by Using a Traceless Controlling Group

We herein report a synthetic strategy for alternating copolymers of styrene and substituted styrenes by utilizing α-styryl boronate pinacol ester ( StBpin ) as the co-monomer through radical alternating copolymerization followed by protodeboronation. The excellent alternating polymerization behavior of the StBpin co-monomer in such a radical polymerization system is considered to be attributed to the steric hindrance and radical stabilization exerted by the Bpin group. This strategy is effective with a wide range of substituted styrene co-monomers regardless of the electronic nature of the substituents, and the protodeboronation of the alternating Bpin-containing polymers is highly efficient without polymer backbone alternation. RAFT living polymerization was also compatible with this approach. Thus, this strategy provides a way to build-up alternating copolymers consisting of similar styrene-type co-monomers, which has been inaccessible by conventional synthetic methods.     

Umpolung Isomerization in Radical Copolymerization of Benzyl Vinyl Ether with Pentafluorophenylacrylate Leading to Degradable AAB Periodic Copolymers

This study revealed that benzyl vinyl ether (BnVE) shows a peculiar isomerization propagation in its radical copolymerization with an electron-deficient acrylate carrying a pentafluorophenyl group (PFA). The co-monomer pair inherently exhibits the cross-over propagation feature due to the large difference in the electron density. However, the radical species of PFA was found to undergo a backward isomerization to the penultimate BnVE pendant giving a benzyl radical species prior to propagation with BnVE. The isomerization brings a drastic change in the character of the growing radical species from electrophilic to nucleophilic, and thus the isomerized benzyl radial species propagates with PFA. Consequently, the two monomers were consumed in the order AAB (A: PFA; B: BnVE) and the unique periodic consumption was confirmed by the pseudo-reactivity ratios calculated by the penultimate model: r₁₁=0.174 and r₂₁=6600 for PFA (M₁) with BnVE (M₂). The pentafluorophenyl ester groups of the resulting copolymers are transformed into ester and amide groups by post-polymerization alcoholysis and aminolysis modifications. The unique isomerization in the AAB sequence allowed the periodic introduction of a benzyl ether structure in the backbone leading to efficient degradation under acid conditions.     

Controlled Radical Copolymerization toward Well-Defined Fluoropolymers

In the past 80 years, fluoropolymers have found broad applications in both industrial and academic settings, owing to their unique physicochemical properties. Copolymerizations of fluoroalkene feedstocks present an important avenue to obtain high-performance materials by merging intrinsic attributes of fluorocarbons and great versatility of comonomers. Recently, while massive investigations have disclosed the great potentials of precisely synthesized polymers, researchers have made considerable efforts to approach well-defined fluorinated copolymers. This minireview discusses challenges in controlled radical copolymerizations (CRCPs) of fluoroalkenes and provides a concise perspective on recent progress in CRCPs of fluoroalkenes (e.g., tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropene, perfluoroalkyl vinyl ethers) with non-fluorinated vinyl comonomers, which have enabled on-demand preparations of various main-chain fluoropolymers with predefined molar masses, low dispersities, as well as regulable chemical compositions and sequences. The synthetic advantages of CRCPs will promote controlled and facile access to customized fluoropolymers for high-tech applications such as batteries, coatings and so on.     

Synthesis of Sequence-specific Poly(ester-carbonate) Copolymers via Chemoselective Terpolymerization Controlled by the Stoichiometric Ratio of Phosphazene/Triethylborane

Chemoselective terpolymerization can produce polymer materials with diverse compositions and sequential structures, and thus have attracted considerable attention in the field of polymer synthesis. However, the intrinsic complexity of three-component system also brings great chanllenge, in regard to the reactivity and selectivity of different monomers. Herein, we report the terpolymerization of CO₂/epoxide/anhydride by a binary organocatalytic C₃N₃-Py-P₃/TEB (triethylborane) system. Both the activity and chemoselectivity were highly dependent upon the molar ratio of C₃N₃-Py-P₃ to TEB, and sequence-controlled poly(ester-carbonate) copolymers were readily synthesized through one-pot/one-step methodology by tuning the stoichiometric ratio of phosphazene/TEB. In particular, C₃N₃-Py-P₃/TEB with a molar ratio of 1/0.5 exhibited an unprecedentedly high chemoselectivity for ring-opening alternating copolymerization (ROAC) of cyclohexene oxide (CHO) and phthalic anhydride (PA) first and then ROAC of CO₂/CHO. Thus, well-defined triblock polycarbonate-b-polyester-b-polycarbonate copolymers can be produced from the mixture of CO₂, CHO and PA using a bifunctional initiator. With C₃N₃-Py-P₃/TEB=1/1, tapered copolymers were obtained, while random copolymers with high content of polycarbonate (PC) were synthesized with further increasing the amount of TEB. The mechanism of the unexpected chemoselectivity was further investigated by DFT calculations.     

水溶性偶氮引发体系引发DMDAAC-AM共聚合

水溶性偶氮引发体系引发DMDAAC-AM共聚合;二甲基二烯丙基氯化铵; 丙烯酰胺; 共聚; AIBA·2HCl-NaHSO3引发剂     

丙烯酰胺-丙烯酰氧乙基三甲基氯化铵共聚合的竞聚率测定

采用溶液聚合制备了新型阳离子共聚物--聚丙烯酰胺基-丙烯酰氧乙基三甲基氯化铵(P(AM-DAC)),采用滴定法测定了其阳离子共聚物的阳离子度.分别采用Fineman-Ross 法、Kelen-Tudos 法和Yezrielev-Brokhina-Roskin法计算出单体竞聚率.结果表明,KT法和YBR法计算较为准确,丙烯酰氧乙基三甲基氯化铵和丙烯酰胺的竞聚率分别为rDAC=0.383 5,rAM=2.286 4.     

氯乙烯/N-取代马来酰亚胺共聚竞聚率及共聚物组成

研究了氯乙烯(VC)与多种N-取代马来酰亚胺的溶液共聚合,求得各对单体的竞聚率.结果表明,各种马来酰亚胺的竞聚率都远高于VC的竞聚率,即N-取代马来酰亚胺单体的活性均比VC单体活性高.计算得到N-取代马来酰亚胺Q和e值.由于苯环的共轭效应,N-苯基及N-取代苯基马来酰亚胺具有较大的Q值.各对单体的e值差别较大,表明有形成交替共聚物的倾向.此外,还考察了聚合过程中共聚物组成的变化,用递推法预测了这类体系共聚物瞬时和累积组成随转化率的变化.     

Living Alternating Ring-Opening Metathesis Copolymerization of 2,3-Dihydrofuran to Provide Completely Degradable Polymers

2,3-Dihydrofuran (DHF) has recently been gaining significant attention as a comonomer in metathesis polymerization, thanks to its ability to provide the resultant polymer backbones with stimuli-responsive degradability. In this report, we present living alternating copolymerization of DHF with less reactive endo-tricyclo[4.2.2.0^2,5]deca-3,9-dienes (TDs) and endo-oxonorbornenes (oxoNBs). By carefully controlling the reactivity of both the Ru initiators and the monomers, we have achieved outstanding A, B-alternation (up to 98 %) under near stoichiometric DHF loading conditions. Notably, we have also found that the use of a more sterically hindered Ru initiator helps to attain polymer backbones with higher DHF incorporation and superior A, B-alternation. While preserving the living characteristics of DHF copolymerization, as evidenced by controlled molecular weights (up to 73.9 kDa), narrow dispersities (down to 1.05), and block copolymer formation, our DHF copolymers could be broken down to a single repeat unit level under acidic conditions. ¹H NMR analysis of the model copolymer revealed that after 24 hours of degradation, up to 80 % of the initial polymer was transformed into a single small molecule product, and after purification, up to 66 % of the degradation product was retrieved. This study provides a versatile approach to improve the alternation and degradability of DHF copolymers.     

二甲基二烯丙基氯化铵的辐射聚合和性质研究

对二甲基二烯丙基氯化铵进行了辐射聚合,得到线型聚合物的交联的水凝胶, 实验测定了线型聚合的转化率与剂量和水凝胶的凝胶的凝胶分数、平衡溶胀与剂量 的关系。结果表明聚二甲基二烯丙基氯化铵水凝胶的凝胶含量与剂量的关系符合 Charlesby-Pinner公式,外推S + S~(1/2) = 2求得凝胶剂量D_g,从而求出G(x) 等值;并首次利用二甲基二烯丙基氯化铵及其聚合物稀水溶液的电导率与浓度的线 性关系,发展了一种对电解质的辐射聚合反应转化率的电导测定法。     

Copolymerization of N-Vinyl-4,5,6,7-tetrahydroindole with Acrylamide

Radical copolymerization of N-vinyl-4,5,6,7-tetrahydroindole with acrylamide in dimethylformamide was studied, and the relative activity constants of the monomers were determined.