新型螺环单体的合成和自由基聚合反应的研究

新型螺环单体的合成和自由基聚合反应的研究王宏鲁剑涛冯品珍（中国科学技术大学研究生院化学部北京１０００３９）关键词自由基聚合，新单体合成，螺环单体，自由基共聚虽然离子型开环聚合早已为人熟知，但是自由基开环聚合反应的研究和应用开发还刚刚起步．...     

SYNTHESIS AND POLYMERIZATION OF 2-OXO-3-METHYLENE-5, 6-DIPHENYL-1,4-DIOXAN

A new cyclic monomer, 2-oxo-3-methylene-5, 6-diphenyl-1, 4-dioxan, was synthesized. Thestructure of the intermediates and the monomer were determined by IR,~1H NMR,~(13)C NMR andelemental analysis. This new monomer is different from other cyclic monomers in this series,it isa solid (mp 108--109℃)and not very reactive, but still can undergo free radical ring-openingpolymerization. The free radical polymerization was carried out at 130℃. The structure of theresulting polymer was discussed and charaterized by IR, ~1H NMR, ~(13)C NMR and elementalanalysis. The molecular weight of the polymer was estimated by viscosity determination.     

Alternating Copolymers from Alkyleneimines. I. Copolymers from Ethyleneimine and Dicarboxylic Anhydrides

Ethyleneimine and dicarboxylic anhydrides were copolymerized to alternating copolymers which possess an ester-amide in the repeating unit. The structure of copolymer was Identified by IR, NMR, and elemental analysis. On taking the structure of copolymer, the nucleophllic reactivity of ethyleneimine, and the electrophilic nature of dicarboxylic anhydride Into consideration, a reaction mechanism was elucidated. It Involves ring opening and a stepwise addition reaction in alternating manner, in that one monomer undergoes ring opening and chain propagation exclusively through the interaction with another monomer that is already present at the polymer chain end. The copolymers obtained from halogen containing dicarboxylic anhydrides are useful as fire-retarding additives for plastics and also as thermosetting resin precursor when anhydrides are partially replaced by maleic anhydride.     

(n-BuCp)_2TiCl_2/Sn/I_s引发合成梳形羟基功能化无规聚苯乙烯及聚合物结构与性能的研究

采用茂金属化合物(n-BuCp)2TiCl2,还原剂(Sn),引发剂苯基缩水甘油基醚甲醛共聚物(Is)组成的催化体系引发苯乙烯活性自由基聚合,合成梳形羟基功能化无规聚苯乙烯.考察了聚合温度、聚合时间及引发剂与单体的比例对苯乙烯聚合的影响.当聚合温度在65～95℃范围内,随着聚合温度的升高,聚合物的分子量及单体转化率增加;在一定温度下,聚合物的分子量与单体转化率之间存在线性增长关系,且聚合物的分子量分布较窄(Mw/Mn=1.6～1.9).采用GPC,WAXD,13C(1H)-NMR对聚合物(沸丁酮可溶级分)的结构与性能进行了表征.GPC结果证明(n-BuCp)2TiCl2/Sn/Is引发苯乙烯聚合为活性聚合;13C-NMR和WAXD结果说明聚苯乙烯链段为无规结构;1H-NMR结果表明聚合物分子链中含有羟基,并根据其结果计算出聚合物分子的臂数为4,与引发剂Is的环氧基团数相等.这些结果证明了其聚合机理是经环氧基团开环后形成的自由基引发苯乙烯自由基聚合.     

β-二酮钛非茂催化剂催化降冰片烯聚合

用 (dibenzoylmethanato) 2 Ti(OPh) 2 [(dbm) 2 Ti(OPh) 2 ]/甲基铝氧烷 (MAO)为代表的新型 β 二酮钛非茂催化剂实现了降冰片烯的聚合 ,得到加成聚合和开环易位聚合的混合物 ,研究了实现高聚合活性所需的特殊条件及所得的聚合物结构 ,主要应用傅立叶转变红外技术 (FTIR)对聚合物结构进行了表征和分析     

ABC type miktoarm star copolymers through combination of controlled polymerization techniques with thiol‐ene and azide‐alkyne click reactions

ABC type miktoarm star copolymer with polystyrene (PS), poly(ε‐caprolactone) (PCL) and poly(ethylene glycol) (PEG) arms was synthesized using controlled polymerization techniques in combination with thiol‐ene and copper catalyzed azide‐alyne “click” reactions (CuAAC) and characterized. For this purpose, 1‐(allyloxy)‐3‐azidopropan‐2‐ol was synthesized as the core component in a one‐step reaction with high yields (96%). Independently, ω‐thiol functionalized polystyrene (PS‐SH) was synthesized in a two‐step protocol with a very narrow molecular weight distribution. The bromo end function of PS obtained by atom transfer radical polymerization was first converted to xanthate function and then reacted with 1, 2‐ethandithiol to yield desired thiol functional polymer (PS‐SH). The obtained polymer was grafted onto the core by thiol‐ene click chemistry. In the following stage, ε‐caprolactone monomer was polymerized from the core by ring opening polymerization (ROP) using tin octoate as catalyst through hydroxyl groups to form the second arm. Finally, PEG‐acetylene, which was simply synthesized by the esterification of Me‐PEG and 5‐pentynoic acid, was clicked onto the core through azide groups present in the structure. The intermediates at various stages and the final miktoarm star copolymer were characterized by ¹H NMR, FTIR, and GPC measurements. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

On the Bulk Properties of a Poly(Bicycloacrylate) Carrying Semifluorinated Side Groups

We prepared a novel fluorinated polymer from a bicycloacrylate monomer, (1H,1H,2H,2H)-perfluorododecyl 2-(bicyclo[3.1.0]hex-1-yl)acrylate, by radical ring opening polymerization. The bulk properties of the polymer were investigated by thermal analysis and X-ray diffraction, which proved the existence of a smectic mesophase up to the isotropization temperature of 74 °C. Furthermore, a solid state NMR study was started to characterize domains with different mobility mainly by ¹³C cross-polarization magic angle spinning and T₂ selective experiments. We found that the polymer is a homogeneous sample with the presence of dynamic motions in the kHz regime below the glass transition temperature.     

Synchronized propagation mechanism for crystalline-state polymerization of p-xylylenediammonium disorbate.

We describe the results of the topochemical polymerization of p-xylylenediammonium disorbate as the bifunctional monomer in the crystalline state via a radical chain polymerization mechanism. The structure and properties of the resulting double-stranded polymer are investigated by X-ray crystal structure and thermal analyses as well as IR spectroscopy. The stereochemical structure of the polymer is confirmed by NMR spectroscopy after the solid-state transformation of the polymer side chain to give the single-stranded chains that are soluble in methanol. We propose a model for the reaction mechanism to provide a ladder polymer in the crystalline state on the basis of the results of single-crystal structure analysis and the observation of the alpha-methyl and alpha-carboxylate propagating radicals by ESR spectroscopy. The two reaction parts of the monomer are synchronized to simultaneously react with the conformational change in a sorbate moiety that is transformed into another sorbate through the diammonium part as the linker.     

N-乙烯基咔唑三羰基铬的合成和自由基聚合反应

合成一种新的金属铬有机单体N-乙烯基咔唑三羰基铬,经元素分析、IR和1HNMR确证和表征.研究结果表明,N-乙烯基咔唑三羰基铬能发生自由基聚合反应,得到结构单元含等物质的量铬的金属有机高分子,苯环及含氮给电子中心的共轭效应能在一定程度上弥补由Cr(CO)₃基团吸电子诱导效应引起的单体聚合活性的下降     

Effect of Temperature on the Cationic Photopolymerization of Epoxides

The effects of temperature on the photoinitiated cationic ring‐opening polymerizations of a number of different epoxide monomers were studied with the aid of a modified optical pyrometer instrument. Depending on the structures of the epoxide monomer, various behaviors were observed. The results were interpreted as due to steric and electronic features inherent in the structures of the monomers that affect the stabilization of the secondary oxonium ions, which are formed as intermediates in these polymerizations. At one extreme, cycloaliphatic epoxides such as cyclohexene oxide give highly reactive oxonium intermediates that exhibit high rates of polymerization even at subambient temperatures. At the other extreme, alkyl glycidyl ethers produce oxonium ion intermediates, which are so stable that they do not spontaneously react to form polymer at room temperature. By manipulation of the structure of the epoxide monomer, novel monomers with tailored reactivities can be prepared.     

环状碳酸酯低聚物的合成及其开环聚合的研究

环状碳酸酯低聚物的合成及其开环聚合的研究陈雨萍魏玮李革（中国科学院化学研究所工程塑料国家重点实验室北京１０００８０）关键词环状碳酸酯低聚物，聚碳酸酯，开环聚合环状单体的开环聚合在合成高聚物方面具有突出的优点，即在聚合过程中没有副产物、热效应低、聚合...     

Demonstration of isospecific free radical polymerization of acrylate controlled by conformation and chirality of monomer

Radical polymerization of lactic acid‐based chiral and achiral methylene dioxolanones, a model for conformationally s‐cis locked acrylate, was carried out with AIBN to demonstrate an isospecific free radical polymerization controlled by chirality and conformation of monomer. Polymerization of the dioxolanones proceeded smoothly without ring opening to give a polymer with moderate molecular weight and 100% of maximum isotacticity. ESR spectrum indicated a twisted conformation of the growing poly(methylene dioxolanone) radical in contrast to an acyclic analogous radical, suggesting a restriction of the free rotation around main chain C_α? C_β bond of the growing radical center. Chirality as well as the polarity and bulkiness of monomer affected the polymer tacticity, and chiral alkyl substituent would afford a high isotactic polymer, in which higher the enantiomeric excess of the monomer was, higher the isotacticity of the polymer was. While, achiral or polar substituents including dibenzyl and trichloromethyl groups would afford an atactic polymer. In addition, glass transition temperature (T_g) of the resulting polymers was significantly high, ranging from 172.2 to 229.8 °C, and even for an isotactic polymer T_g was as high as 206.8 °C. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2007–2016     

Synthesis and characterization of polyoctenamer with WCl6?e−?Al?CH2Cl2 catalyst system via ring‐opening metathesis polymerization

A typical low‐strain monomer, cyclooctene, was polymerized via ring‐opening metathesis polymerization with electrochemically produced active species. The structural properties of the polyoctenamer were determined by NMR, gel‐permeation chromatography and differential scanning calorimetry. Analysis of the polyoctenamer microstructure by ¹H and ¹³C NMR spectroscopy indicates that the polymer contains a highly cis stereoconfiguration of the double bonds (σ_c = 0.75). The resulting polymer is of low molecular weight and has a reasonably broad molecular weight distribution (M_w = 18 000, PDI = 1.9). The glass transition temperature and melting point of the polyoctenamer are ?11.3 °C and 36.5 °C respectively. Copyright © 2005 John Wiley & Sons, Ltd.     

Ring‐opening polymerization of L‐lactide by rare‐earth tris(4‐tert‐butylphenolate) single‐component initiators

The ring‐opening polymerization of L ‐lactide initiated by single‐component rare‐earth tris(4‐tert‐butylphenolate)s was conducted. The influences of the rare‐earth elements, solvents, temperature, monomer and initiator concentrations, and reaction time on the polymerization were investigated in detail. No racemization was found from 70 to 100 °C under the examined conditions. NMR and differential scanning calorimetry measurements further confirmed that the polymerization occurred without epimerization of the monomer or polymer. A kinetic study indicated that the polymerization rate was first‐order with respect to the monomer and initiator concentrations. The overall activation energy of the ring‐opening polymerization was 79.2 kJ mol^?1. ¹H NMR data showed that the L ‐lactide monomer inserted into the growing chains with acyl–oxygen bond cleavage. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6209–6215, 2004     

Selectivity of siloxane-siloxane copolymer synthesis by ring opening polymerization

Anionic ring-opening polymerization of 1,1-diphenyl-2,2,3,3-tetramethylcyclotetrasiloxane was studied as a model polymerization of cyclic siloxane with mixed siloxane units. Sequencing of siloxane units was investigated by ²⁹Si NMR. Various initiator-promoter-solvent systems were used. In most cases reaction was highly chemoselective, as sequencing were not affected by back biting, chain transfer and terminal unit exchange processes. Reactions showed, however, low regioselectivity in monomer ring opening. The coordination of the metal counter-ion to monomer plays a considerable role in propagation and affects sequencing of the polymer.     

Free‐radical polymerization of dioxolane and dioxane derivatives: Effect of fluorine substituents on the ring opening polymerization

Partially fluorinated and perfluorinated dioxolane and dioxane derivatives have been prepared to investigate the effect of fluorine substituents on their free‐radical polymerization products. The partially fluorinated monomer 2‐difluoromethylene‐1,3‐dioxolane (I) was readily polymerized with free‐radical initiators azobisisobutyronitrile or tri(n‐butyl)borane–air and yielded a vinyl addition product. However, the hydrocarbon analogue, 2‐methylene‐1,3‐dioxolane (II), produced as much as 50% ring opening product at 60 °C by free‐radical polymerization. 2‐Difluoromethylene‐4‐methyl‐1,3‐dioxolane (III) was synthesized and its free‐radical polymerization yielded ring opening products: 28% at 60 °C, decreasing to 7 and 4% at 0 °C and −78 °C, respectively. All the fluorine‐substituted, perfluoro‐2‐methylene‐4‐methyl‐1,3‐dioxolane (IV) produced only a vinyl addition product with perfluorobenzoylperoxide as an initiator. The six‐membered ring monomer, 2‐methylene‐1,3‐dioxane (V), caused more than 50% ring opening during free‐radical polymerization. However, the partially fluorinated analogue, 2‐difluoromethylene‐1,3‐dioxane (VI), produced only 22% ring opening product with free‐radical polymerization and the perfluorinated compound, perfluoro‐2‐methylene‐1,3‐dioxane (VII), yielded only the vinyl addition polymer. The ring opening reaction and the vinyl addition steps during the free‐radical polymerization of these monomers are competitive reactions. We discuss the reaction mechanism of the ring opening and vinyl addition polymerizations of these partially fluorinated and perfluorinated dioxolane and dioxane derivatives. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5180–5188, 2004     

A new approach to control crystallinity of resulting polymers: Self‐condensing ring opening polymerization

The cationic polymerization of 3‐methyl‐3‐oxetanemethanol was initiated using BF₃·OEt₂. The low ratio of catalyst to monomer results in a mainly linear or slightly branched polymer, and the high catalyst to monomer ratio leads to a hyperbranched polymer. The hyperbranched polyether yielded is amorphous, and the essentially linear version obtained is partially crystalline. In other words, the degree of branching and the crystallinity of resulting polymers are dependent on the catalyst to monomer ratio. Therefore a new approach to control the crystallinity of resulting polymers in self‐condensing ring opening polymerization was developed.     

Soluble tin(II) macroinitiator adducts for the controlled ring‐opening polymerization of lactones and cyclic carbonates

Polyesters and poly(ester carbonates) were synthesized via ring‐opening polymerization with new tin(II) macroinitiator adducts containing oligomeric L ‐lactide (LLA), rac‐lactide (rac‐LA), and ?‐caprolactone (CL). The novel initiating species were synthesized by the reaction of LLA, rac‐LA, or CL with Sn(OEt)₂ (monomer concentration/initiator concentration ≤20) and then were dissolved in methylene chloride or toluene and stored in a stoppered flask for the subsequent ring‐opening polymerization of cyclic esters and carbonates. The soluble tin alkoxide macroinitiators yielded predictable and quantitative initiation of polymerization for up to 1 month of storage time at room temperature. The resulting polymers displayed low polydispersity (≤1.5), and a high monomer conversion (>95%) was obtained within relatively short polymerization times (≤2 h). Adjusting the monomer/macroinitiator ratio effectively controlled the molecular weights of the polymers. NMR was used to characterize the initiating species and polymer microstructure, and size exclusion chromatography was used to determine the molecular weight properties of the polymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3434–3442, 2002     

二茂钛/锡/环氧化合物引发苯乙烯活性自由基聚合的研究

采用单茂钛CpTiCl3和二茂钛金属化合物(n-BuCp)2TiCl2,引发剂4-甲氧苯基缩水甘油基醚(I1),1,4-丁二醇二缩水甘油基醚(I2),4,4′-亚甲基二(N,N-二缩水甘油基苯胺)(I4)和苯基缩水甘油基醚甲醛共聚物(I5)及还原剂Sn组成引发体系,引发苯乙烯活性自由基聚合,合成线型和多臂聚合物.探讨了不同茂钛金属化合物、引发剂和还原剂对苯乙烯聚合的影响;并采用13C-NMR和GPC对聚苯乙烯的结构和性能进行了表征.结果表明所得聚合物是无规聚苯乙烯,聚合物分子量高,分子量分布窄.聚合行为属于活性自由基聚合.     

Bis allyl benzoxazine: Synthesis, polymerisation and polymer properties

A bis benzoxazine monomer with allyl groups viz: 2,2′-bis (8-allyl-3-phenyl-3,4-dihydro-2H-1,3-benzoxazinyl) propane (Bz-allyl) was synthesized via a solventless method from 2,2′diallyl bisphenol-A, paraformaldehyde and aniline. The chemical structure of Bz-allyl was confirmed by FTIR, ¹H NMR and ¹³C NMR analyses. The monomer manifested a two-stage thermal polymerisation pattern. The first stage was attributed to the polymerisation of the allyl groups and the second to the ring - opening polymerisation of benzoxazine moiety. The polymerisation profile was investigated with DSC, FT-IR, TGA and pyrolysis-GC techniques. A polymerisation mechanism involving the electrophilic addition of the propagating iminium cation on the aniline ring in lieu of the activated sites of bisphenol-A, (which are blocked by allyl and alkyl substituents) was proposed. Additional cross-linking was provided by thermal addition polymerization of allyl groups. As a result of altered cross-linking via the aniline moiety and the additional cross-linking via allyl groups, the cured polymer exhibited a T_g of ca. 300 °C and high crosslink density. The thermal stability of this polymer was also substantially higher vis-à-vis that of the bisphenol-A based polybenzoxazine. The work focuses on the manipulation of benzoxazine monomer structure to alter the ring-opening polymerisation mechanism and cross-linking to derive polybenzoxazine with improved properties.