Ethene-butadiene copolymers by single-site catalysts

Constrained geometry catalysts ([Me₂Si(N^tBu)(Me₄Cp)]TiCl₂) were used to copolymerize ethene and 1,3-butadiene. It is possible to incorporate 17 mol% of butadiene, other catalyst systems such as CpTiCl₃/MAO show much lower incorporation. More than 300 000 kg of copolymer can be obtained by one mol of the catalysts in one hour. The microstructure of the copolymers has been investigated by ¹H- and ¹³C-NMR spectroscopy. The butadiene is incorporated mainly in 1,4-trans- and 1,2-structure. The high amount of 9-29% of vinyl groups offers the possibility of an easy vulcanisation. The molecular weights of these elastomers are high with values of 250 000. Important is the low glass transition temperature of −28 °C of a copolymer with 7 mol% of butadiene.     

甲基丙烯酸丁酯和苯乙烯的原子转移自由基共聚

研究了甲基丙烯酸丁酯（ＢＭＡ）和苯乙烯（Ｓ）这两种不同极性单体的原子转移自由基嵌段共聚和无规共聚,得到了实测分子量与理论分子量相近,分子量分布较窄的嵌段共聚物和无规共聚物．聚合过程中分子量和单体转化率成比例增加,多分散性指数变化不大．用１Ｈ ＮＭＲ法测定共聚组成,Ｋｅｌｅｎ Ｔｕｄｏｓ法计算竞聚率．得到ｒＳｔ＝０９１,ｒＢＭＡ＝０３２．     

利用大分子单体技术合成接枝共聚物

大分子单体和小分子共单体共聚是合成接枝共聚物的重要途径之一。本文综述了大分子单体通过各种聚合方式(自由基共聚、离子型共聚、配位共聚、基团转移共聚和逐步共聚)和普通小分子单体的共聚反应,详细讨论了大分子单体和小分子单体的自由基共聚反应动力学,并简要介绍了接枝共聚物的应用背景。     

Tuning the parameters of the suspension polymerization of styrene,divinylbenzene, and N‐(p‐vinylbenzyl)‐ 4,4‐dimethylazlactone

Azlactone‐functionalized microporous polystyrene resins were synthesized by suspension polymerization of styrene, divinylbenzene and N‐(p‐vinylbenzyl)‐4,4‐dimethylazlactone (VBM). A fractional factorial design of experiments (DOE) has been used to evaluate the influence of several parameters (factors) on the physical and chemical properties (responses) of the resins. Six factors were considered: (i) the organic/aqueous phase ratio, (ii) the amount of the functional monomer N‐(p‐vinylbenzyl)‐4,4‐dimethylazlactone, (iii) the amount of stabilizer, (iv) the amount of initiator, (v) the stirring speed, and (vi) the equilibration time. The process responses were the yield of polymerization, the diameter of the beads and their polydispersity, their swelling ratio in dichloromethane and the accessibility ratio of the immobilized azlactone sites. This methodology enables the determination of an optimal combination of the six factors to synthesize beads in high yield (92%) with remarkable properties for SPOS applications (azlactone sites loading = 1.57 mmol/g, swelling ratio in dichloromethane = 5.0 mL/g and 100% accessibility ratio). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3677–3686, 2007     

Kinetic study of high-conversion copolymerization of butyl acrylate with methyl methacrylate in solution

Butyl acrylate (BA) and methyl methacrylate (MMA) have been copolymerized in a 3 mol/L benzene solution using 2,2′-azobis(isobutyronitrile) (AIBN) as initiator over a wide composition and conversion range. The overall copolymerization parameter k_p/k_t^1/2 and the composition of the copolymer formed have been measured as a function of conversion. Theoretical values of the coupled parameter k_p/k_t^1/2 calculated from the implicit penultimate unit model and those of cumulative copolymer composition, determined from the Mayo—Lewis terminal model, have been correlated with those experimentally obtained. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1961–1965, 1997     

L—丙氨酸与甘氨酸的N—羧基—环内酸酐共聚合的研究

从模拟蚕丝素蛋白的角度,研究了L-丙氨酸的N-羧基-环内酸酐(L-Ala-NCA)与甘氨酸的N-羧基-环内酸酐(Gly-NCA)在硝基苯溶剂中,正丁胺引发下的共聚合反应。讨论了单体投料比,反应温度对聚合速率及产物分子量的影响。并从实验中发现,在不加入引发剂的情况下,L-Ala-NCA和Gly-NCA共结晶能在甲苯介质中顺利地进行非均相的热开环共聚,且产物的分子量远高于采用引发剂的均相聚合体系产物的相应值。     

A New,Practical Formulation of the Multicomponent Copolymerization Equation

A general and rigorous new formulation of the multicomponent extension to the Mayo Lewis copolymerization equation is presented based in matrix notation. In contrast to the original Walling and Briggs formulation, which was based on determinants and difficult to apply in practice, this new formulation is explicit, easy to implement, and introduces a natural scaling to the problem. The approach is illustrated with calculation of instantaneous composition and compositional drift with conversion for 4 and 6 monomers.

     

悬浮法合成聚丙烯接枝丙烯酸

用过氧化二苯甲酰作引发剂以水相悬浮法合成聚丙烯接枝丙烯酸。通过反应条件、组分等因素对PP的接枝率和接枝效率的影响研究,确定较佳配比工艺条件：溶用莳8-0min;反应温度90℃;反应时间90min;在氮气气氛中,丙烯酸7％;过氧化二苯甲酰3．3％;二甲苯25％;水和聚丙烯的重量比为3：1;若加入适量催化剂（1－1．7％0异氰尿酸三烯丙酯能显著提高接枝率。用此PP－g-AA作CaCO3、PP/PA6和合物的相容剂,材料的力学性能有很大的提高。     

BF_3,络合的丙烯酸乙酯与丙烯的共聚机理

BF_3络合的丙烯酸乙酯(EA)与丙烯(P)在25℃进行自由基共聚。聚合速率和引发剂浓度的平方根成直线关系。链转移剂CCl_4可显著影响共聚物的[η];溶剂的介电常数越小,共聚反应速率越大;两种单体浓度相等时共聚反应速率最大。~1H-NMR和 _13C-NMR表明,当[EA·BF_3]/[EA·BF_3]+[P]>O.5时所得共聚物为富于EA的无规共聚物。实验数据表明,共聚反应按三元络合物与二元络合物的无规共聚机理进行,当[EA·BF_3]/[EA·BF_3]+[P]<0.5时,得到交替共聚物,共聚反应按三元络合物均聚机理进行。UV光谱测得了戊烯-1(丙烯的同系物)与EA·BF_3三元络合物的存在,这对三元络合物的均聚机理是有力的证据。     

Alternating copolymerization of carbon dioxide and epoxide by manganese porphyrin: The first example of polycarbonate synthesis from 1-atm carbon dioxide

The first successful example of the formation of polycarbonate from 1-atm carbon dioxide and epoxide was demonstrated by the alternating copolymerization of carbon dioxide and epoxide with manganese porphyrin as a catalyst. The copolymerization of carbon dioxide and cyclohexene oxide with (porphinato)manganese acetate proceeded under the 1-atm pressure of carbon dioxide to give a copolymer with an alternating sequence. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3549–3555, 2003     

A new titanium (IV) complex bearing phenoxyimine‐fluorene ligand and its use as catalyst for ethylene homo‐ and copolymerization

A new titanium (IV) complex bearing phenoxyimine‐fluorene ligand was prepared and its behaviors in ethylene homo‐ and copolymerization with 1‐hexene, 1‐octene, and norbornene in the presence of modified methylaluminoxane (MMAO) were studied respectively. The effects of various polymerization conditions including polymerization temperature, ethylene pressure and the concentration of comonomer on the catalytic activities and properties of the resultant polymer were investigated. The broad molecular weight distribution of resulting polymer indicated that the multiple active species were formed during polymerization. Such complex showed good catalytic activities in ethylene homo‐ and copolymerizations and good capabilities of incorporating various comonomers into polyethylene backbone. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1617–1621, 2010     

水溶性导电聚苯胺的制备*

水溶性聚苯胺在防腐涂料、电磁屏蔽、生物医学等领域有重要应用前景。该文结合本研究组在水溶性聚苯胺自支撑膜方面的研究进展,总结了水溶性聚苯胺的制备方法,并重点综述了用嵌段和接枝等共聚法制备的水溶性聚苯胺及其共聚机理,提出水溶性导电聚苯胺今后的研究方向。     

Cationic ring-opening copolymerization of seven-membered cyclic sulfite and oxetane in one-shot feeding

Cationic copolymerization of seven-membered cyclic sulfite, 1,3,2-dioxathiepane-2-oxide (1) and oxetane (2) in one-shot feeding was carried out to obtain the corresponding copolymer. When a mixture of equimolar amount of 1 and 2 reacted at 0°C in the presence of methyl trifluoromethanesulfonate (T fOMe) as a cationic initiator, T fOMe and 2 were completely consumed without the consumption of 1. After rising the polymerization temperature up to 25°C, 1 started to be consumed to obtain the corresponding copolymer of 1 and 2. The obtained copolymer showed a unimodal GPC curve, and it afforded a polyether showing a unimodal GPC after alkaline hydrolysis. These results strongly suggested the occurrence of the block copolymerization in one-shot feeding. From the molecular orbital examination, the formation of block copolymerization in one-shot feeding was discussed to be caused by the much larger polymerizability of 2 than that of 1. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1007–1012, 1997     

A Novel Fission Process in Mini-emulsion RAFT Polymerization: Shell Crosslinked Nanoparticles as a Model

Shell crosslinked nanoparticles, prepared from copolymerization of styrene and disulfide crosslinker, using poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) as stabilizer and macroinitiator, exhibited a special fission behavior during the mini-emulsion RAFT polymerization process.     

A polarity‐activation strategy for the high incorporation of 1‐alkenes into functional copolymers via RAFT copolymerization

A new synthetic methodology for the preparation of copolymers having high incorporation of 1‐alkene together with multifunctionalities has been developed by polarity‐activated reversible addition‐fragmentation chain transfer (RAFT) copolymerization. This approach provides well‐defined alternating poly(1‐decene‐alt‐maleic anhydride), expanding the monomer types for living copolymerizations. Although neither 1‐decene (DE) nor maleic anhydride (MAn) has significant reactivity in RAFT homopolymerization, their copolymers have been synthesized by RAFT copolymerizations. The controlled characteristics of DE‐MAn copolymerizations were verified by increased copolymer molecular weights during the copolymerization process. Ternary copolymers of DE and MAn, with high conversion of DE, could be obtained by using additive amounts (5 mol %) of vinyl acetate or styrene (ST), demonstrating further enhanced monomer reactivities and complex chain structures. When ST was selected as the third monomer, copolymers with block structures were obtained, because of fast consumption of ST in the copolymerization. Moreover, a wide variety of well‐defined multifunctional copolymers were prepared by RAFT copolymerizations of various functional 1‐alkenes with MAn. For each copolymerization, gel permeation chromatography analysis showed that the resulting copolymer had well‐controlled M_n values and fairly low polydispersities (PDI = 1.3–1.4), and ¹H and ¹³C NMR spectroscopies indicated strong alternating tendency during copolymerization with high incorporation of 1‐alkene units, up to 50 mol %. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3488–3498, 2008     

Multimonomer partitioning in latex systems with moderately water-soluble monomers

Simple equations describing monomer partitioning in latices during intervals 2 and 3 in emulsion polymerization with any number of low to moderately water soluble monomers were derived from the extended Morton equation by making various assumptions. It appears that it is mainly the combinatorial entropy of mixing that governs the partitioning behavior, and that other contributions to the free energy of the monomers in the polymer particles are marginal. Experimental results with styrene, methyl methacrylate, and methyl acrylate confirm the validity of the assumptions. In interval 3 of emulsion polymerization the sum of all contributions to the free energy of the monomers in the particles other than the combinatorial entropy of mixing can be taken as a constant that is dependent only on the monomer composition in the particles and independent of the degree of swelling of the particles. The only parameters one needs to know to calculate the monomer concentrations in all phases with help of the derived equations, are the saturation concentrations of each monomer in the polymer particles, and the saturation concentrations of each monomer in the aqueous phase. © 1994 John Wiley & Sons, Inc.     

Reactive surfactants in heterophase polymerization. XXV. Core–shell lattices stabilized with a mixture of maleic anionic and styrenic nonionic surfactants

Core–shell lattices with a polystyrene core and a polystyrene/butyl acrylate shell with more than 40% solid contents were produced using a combination of sodium dodecyl maleate hemiester as anionic surfactant and styrenic block copolymer of butylene oxide and ethylene oxide as nonionic surfactant. Stable lattices able to resist rather high concentrations of electrolytes can be obtained, provided a careful protocol of the addition of surfactants is used. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2251–2262, 1999     

A novel aromatic–aliphatic copolyester consisting of poly(1,4‐dioxan‐2‐one) and poly(ethylene‐co‐1,6‐hexene terephthalate): Preparation,thermal, and mechanical properties

A novel multiblock aromatic–aliphatic copolyester poly(ethylene‐co‐1,6‐hexene terephthalate)‐copoly(1,4‐dioxan‐2‐one) (PEHT‐PPDO) was successfully synthesized via the chain‐extension reaction of dihydroxyl teminated poly(ethylene‐co‐hexane terephthalate) (PEHT‐OH) with dihydroxyl teminated poly(1,4‐dioxan‐2‐one) (PPDO‐OH) prepolymers, using toluene‐2,4‐diisocyanate as a chain extender. To produce PEHT‐OH prepolymer with an appropriate melting point which can match the reaction temperature of PEHT‐OH prepolymer with PPDO‐OH prepolymer, 1,6‐hexanediol was used to disturb the regularity of poly(ethylene terephthalate) segments. The chemical structures and molecular weights of PEHT‐PPDO copolymers were characterized by ¹H NMR, FTIR, and GPC. The DSC data showed that PPDO‐OH segments were miscible well with PEHT‐OH segments in amorphous state and that the crystallization of copolyester was predominantly contributed by PPDO segments. The TGA results indicated that the thermal stability of PEHT‐PPDO was improved comparing with PPDO homopolymer. The novel aromatic–aliphatic copolyesters have good mechanical properties and could find applications in the field of biodegradable polymer materials. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2828–2837, 2010