Kinetik und Mechanismus der ringöffnenden Polymerisation von L(—)-Lactid

Suitable initiators for polymerization of lactide are: diethylzinc, triethlaluminium or tin (IV) chloride; the following compounds have been ineffectual: triethyloxonium tetrafluoroborate, tropylium tetrafluoroborate, tritylium hexachloroantimonate, phenyldiazonium hexafluorophosphate or alumintium chloride. The polymerization was found to be a first order reaction in respect to monomer concentration. Concentration of active centers remains constant over whole the polymerization time. Deu to transesterification reactions there are rather strong deviations from an ideal living polymerization system. A coordinative polymerization mechanism is discussed. The overall activation energy amounts to 18.9 (kcal/Mol).     

Ring‐opening polymerization of cyclohexene oxide by recyclable scandium triflate in room temperature ionic liquid

In this article, we provide a concept of a two‐phase polymerization system consisting of immiscible monomer and room temperature ionic liquid (IL). The catalyst is immobilized in the IL phase where polymerization takes place. The produced polymer is extracted by the monomer, and the remaining IL phase is catalytically active for more polymerizations. Thus, common volatile organic solvents are no longer needed. Ring‐opening polymerization of cyclohexene oxide (CHO) in 1‐n‐butyl‐3‐methylimidazolium tetrafluoroborate IL ([bmim][BF₄]) using scandium triflate [Sc(OTf)₃] catalyst serves as a realistic example of such concept. The yield of polyCHO in [bmim][BF₄] is higher than that in bulk. IL containing Sc(OTf)₃ can be used for at least three times. A circulatory polymerization process is carried out with added catalyst to keep a relatively high yield in following circulation processes. The assignments of proton signals of polyCHO in ¹H NMR are discussed in detail. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Polymerization characteristics and thermal degradation study of poly(phenylene sulfide ketone)

Poly(phenylene sulfide ketone) (PPSK) was synthesized by the reaction of sodium sulfide with 4,4′‐dichlorobenzophenone in N‐methyl‐2‐pyrrolidinone through the Phillips process. The effect of water hydration of sodium sulfide in solution, polymerization temperature, polymerization time, and stoichiometric ratio of monomers on the polymerization behavior of PPSK were investigated with respect to inherent viscosity and yield. Thermal degradation parameters of PPSK synthesized were investigated by dynamic thermogravimetry. To determine thermal degradation energy, Kissinger, Ozawa, and Friedman methods were used and activation energies were 202.3, 233.6, and 232.2 kJ/mol, respectively. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1329–1337, 2000     

Dithioester functionalization of poly(cyclohexene oxide) and its application to obtain block copolymers

A new method of introducing dithioester groups into the polymer chain of poly(cyclohexene oxide) is reported. It includes the use of diaryliodonium salt and an aromatic dithioacid as a redox couple to initiate the cationic polymerization of cyclohexene oxide. It was found that the dithioacid by itself cannot start the polymerization of cationic polymerizable monomers; however, in combination with a diaryliodonium salt, an exothermic reaction was produced, yielding a thiocarbonylthio‐functionalized polyether. Thermal profiles of the redox polymerizations were determined by means of optical pyrometry. A preliminary study showed that when the poly(cyclohexene oxide) functionalized with dithioester groups was introduced into the radical polymerization of styrene, the polystyryl growing radicals reacted with the dithioester‐functionalized polyether to form a block polymer. The amount of polyether actually incorporated into the block copolymer was calculated to be 70% of the initial amount of poly(cyclohexene oxide)/dithiobenzoic acid charged into the reactor. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polymerization of trithiane

The catalytic solid-state polymerization of trithane to polythiomethylene has been studied. The polymerization can be initiated by wide varieties of substances such as metal salts, halogen, and active organic halides. The polymerization proceeds in solid-state without topochemical process. The catalytic irreversible degradation of polythiomethylene to dimethyl sulfide and carbon disulfide has been observed.     

Synthesis of poly(cyclohexene oxide)‐block‐polystyrene by combination of radical‐promoted cationic polymerization,atom transfer radical polymerization and click chemistry

The combination of radical‐promoted cationic polymerization, atom transfer radical polymerization (ATRP) and click chemistry was employed for the efficient preparation of poly(cyclohexene oxide)‐block‐polystyrene (PCHO‐b‐PSt). Alkyne end‐functionalized poly(cyclohexene oxide) (PCHO‐alkyne) was prepared by radical‐promoted cationic polymerization of cyclohexene oxide monomer in the presence of 1,2‐diphenyl‐2‐(2‐propynyloxy)‐1‐ethanone (B‐alkyne) and an onium salt, namely 1‐ethoxy‐2‐methylpyridinium hexafluorophosphate, as the initiating system. The B‐alkyne compound was synthesized using benzoin photoinitiator and propargyl bromide. Well‐defined bromine‐terminated polystyrene (PSt‐Br) was prepared by ATRP using 2‐oxo‐1,2‐diphenylethyl‐2‐bromopropanoate as initiator. Subsequently, the bromine chain end of PSt‐Br was converted to an azide group to obtain PSt‐N₃ by a simple nucleophilic substitution reaction. Then the coupling reaction between the azide end group in PSt‐N₃ and PCHO‐alkyne was performed with Cu(I) catalysis in order to obtain the PCHO‐b‐PSt block copolymer. The structures of all polymers were determined. Copyright © 2010 Society of Chemical Industry     

Phthalic anhydride promoted ring‐opening polymerization of cyclohexene oxide catalyzed by dinuclear chromium complex supported by piperazine‐bridged [ONSO] ligand

New bimetallic chromium complexes bearing a piperazine‐bridged tetradentate‐dianionic iminethiobis(phenolate) (ONSO) ligand and an ancillary chloride group (complex 1 ) have been developed. Of interest, it was found that the complex 1 catalyzed copolymerization of cyclohexene oxide with phthalic anhydride (PA) gives a product with more than 97% ether linkage content, i.e. selective synthesis of poly(cyclohexene oxide), which is in sharp contrast to the mononuclear [ONSO]CrCl analogue where a resulting polymer with more than 86% ester units is achieved under identical conditions. The influences of PA loading, reaction time and temperature on the polymerization were investigated. According to the kinetics data, the apparent activation energy of the ring‐opening polymerization of cyclohexene oxide is 12.5 kJ mol^?1. A cationic polymerization mechanism is proposed according to the polymer structure and the interaction between metal complex 1 and PA. © 2019 Society of Chemical Industry     

Antioxidants and stabilizers, 116 Influence of the carbon black chezacarb EC on polyolefin thermooxidation: A model study with cyclohexene doped with chain-breaking antioxidants

The ageing of polyolefins is accelerated by carbon black Chezacarb EC used as a filler. Conditions for selection of suitable chain-breaking antioxidants protecting against degradation were simulated using cyclohexene doped with various amounts of carbon black and oxidized at 60°C. The results obtained reveal an acceleration of cyclohexene oxidation in the phase following the induction period (IP). The oxidation acceleration is similar to the effect caused by powdered copper(0) or copper(II) ions. Polynuclear phenolic antioxidants are able to stabilize cyclohexene for periods longer than 120 h only in the presence of low amounts of Chezacarb (up to 0.5 wt.-%). At higher Chezacarb concentrations, merely a prolongation of IP may be achieved. Arylene diamines are efficient stabilizers only if combined with a high concentration of Chezacarb (10 wt.-%). None of the chain-breaking antioxidants used was able to diminish the oxidation rate of cyclohexene in the phase after IP.     

Synthesis of novel sulfonium salts and cationic polymerization of epoxides and vinyl ether

Novel 1‐methoxycarbonylethylmethylphenylsulfonium salts with nonnucleophilic anions, namely, hexafluorophosphate, hexafluoroantimonate, and tetrafluoroborate, were synthesized by the reaction of 1‐methoxycarbonylethylphenylsulfide and dimethyl sulfate followed by anion exchange with potassium hexafluorophosphate, sodium hexafluoroantimonate, and sodium tetrafluoroborate, respectively. The cationic polymerization (photopolymerization and thermal polymerization) of epoxy and vinyl ether monomers was carried out to demonstrate the applicability of the newly synthesized sulfonium salts. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3157–3163, 2007     

Primary particle stability in bulk polymerization of vinyl chloride at high ion strength

Tetrabutyl ammonium tetrafluoroborate and tetrabutyl ammonium chloride dissociate completely in vinyl chloride (VCM). These salts, when added to colloidal dispersions of PVC primary particles in VCM prepared by bulk polymerization, cause the particles to flocculate, showing that the primary particles were electrostatically stabilized. When bulk polymerizations were carried out in the presence of the same quarternary ammonium salts, smaller primary particles were obtained than in additive-free polymerizations. Addition of tetrabutylammonium tetrafluoroborate to a suspension polymerization increased the porosity of the resin.     

Synthesis of hybrid liquid crystalline block copolymers by combination of cationic or promoted cationic and free-radical polymerizations

Summary The synthesis of two new classes of liquid crystalline block copolymers (1–5) by a two-step combination of cationic and free-radical polymerizations is described. An azomacroinitiator was prepared first by cationic polymerization of tetrahydrofuran or promoted cationic polymerization of cyclohexene oxide, which was then used to initiate the free-radical polymerization of an acrylate monomer containing a variously substituted biphenyl mesogenic group. The semicrystalline and liquid crystalline blocks were essentially microphase-separated and gave rise to different thermotropic mesophases.     

The use of microwave irradiation for the easy synthesis of graphene-supported transition metal nanoparticles in ionic liquids

Stable ruthenium or rhodium metal nanoparticles were supported on chemically derived graphene (CDG) surfaces with small and uniform particle sizes (Ru 2.2 ± 0.4 nm and Rh 2.8 ± 0.5 nm) by decomposition of their metal carbonyl precursors by rapid microwave irradiation in a suspension of CDG in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate. The graphene-supported hybrid nanoparticles were shown to be active and could be re-used at least 10 times as catalysts for the hydrogenation of cyclohexene and benzene under organic-solvent-free conditions with constant activities up to 1570 mol cyclohexane × (mol metal)⁻¹ × h⁻¹ at 4 bar and 75 °C.     

The polymerization behaviour of 1-benzyl-2,2-dimethylaziridine

Summary The polymerization of 1-benzyl-2,2-dimethylaziridine (BDMA) with triethyioxonium tetrafluoroborate (TEFB) under different reaction conditions was found to be impossible, although the initiation reaction (formation of 1-benzyl-1-ethyl-2,2-dimethylaziridinium tetrafluoroborate) was fast and quantitative. BDMA does copolymerize with 1-benzylaziridine (BA) but the amount of BDMA in the copolymer is always inferior to 50%. The reactivity parameters of the copolymerization (in dichloromethane at 20°C) are r_BA = 3.1 and r_BDMA = 0.0. These results demonstrate the importance of the presence of substituents on the polymerization behaviour of N-alkylaziridines.     

Synthesis and characterization of epoxy-chain end(s) functional macromonomer of polystyrene and its use in photoinitiated cationic polymerization

A novel epoxy chain-end(s) functional polystyrene macromonomer (PSt-CHO) was prepared via free radical polymerization (FRP) of styrene (St) initiated by 4,4′-azobis(3-cyclohexenylmethyl-4-cyanopentanoate) (ACCP) azo initiator and epoxidation on workup with 3-chloroperoxybenzoic acid under inert atmosphere in methylene chloride at 0 °C. 4,4′-Azobis(4-cyanopentanoyl chloride) (ACPC) was obtained by the reaction of 4,4′-azobis(4-cyanopentanoic acid) (ACPA) with phosphorus pentachloride in methylene chloride. The ACCP was synthesized by the condensation reaction of 3-cyclohexene-1-methanol with ACPC. The FRP of styrene with ACCP has yielded polystyrene with cyclohexene end(s) group (PSt-CH). Epoxidation of the PSt-CH was performed using 3-chloroperoxybenzoic acid to obtain epoxy chain-end(s) functional polystyrene macromonomer (PSt-CHO). This macromonomer was used as precursor in photoinitiated cationic polymerization for obtaining brush-type and graft copolymers. Photoinitiated cationic homopolymerization of the macromonomer in the presence of diphenyliodonium salt at λ = 300 nm yielded brush-type polymers. Photoinitiated cationic copolymerization of the macromonomer with cyclohexene oxide (CHO) monomer and diphenyliodonium salt at λ = 350 nm produced graft copolymers. The polymers synthesized were characterized by means of FTIR, ¹HNMR and gel permeation chromatography measurements. All the spectroscopic studies revealed that a macromonomer of polystyrene with cyclohexene oxide (CHO) functionality at the chain end(s) (PSt-CHO) and their brush-type and graft copolymers were obtained.     

Reverse atom transfer radical polymerization of methyl methacrylate in imidazolium ionic liquids

Reverse atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) employing 2,2-azobisisobutyronitrile (AIBN)/CuCl₂/bipyridine(bipy) as the initiating system was approached at 80 °C in two ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate ([C₄mim][BF₄]) and 1-dodecyl-3-methylimidazolium tetrafluoroborate ([C₁₂mim][BF₄]), respectively. The polymerization in [C₁₂mim][BF₄] proceeded in a well-controlled manner as evidenced by kinetic studies, end group analysis, chain extension, and block copolymerization results, but not in [C₄mim][BF₄] presumably due to poor solubility of PMMA in it. The kinetic study of reverse ATRP of MMA in recycled [C₁₂mim][BF₄] suggested that this ionic liquid could be re-used as reaction solvent after simple purification, without affecting the living nature of polymerization.     

Polymerization of epoxides and vinyl monomers by nitrosyl hexafluorophosphate

Summary The polymerization of certain 1,2-epoxides, styrene and n-butyl vinyl ether has been accomplished by the use of nitrosyl hexafluorophosphate as the initiator. Heretofor, nitrosyl hexafluorophosphate has been known as an initiator only for tetrahydrofuran. The polymers prepared had broad molecular weight distributions.Nitrosyl hexafluorophosphate (NOPP₆) has been used to initiate the polymerization of tetrahydrofuran (ECKSTEIN and DREYFUSS, 1979; SEUNG, et al., 1981). In this communication we report on the use of NOPF₆ for the polymerization of three 1,2-epoxides, namely styrene oxide (SO), cyclohexene oxide (CHO), and 1,2-epoxybutane (EB). In addition, styrene (S) and n-butyl vinyl ether (nBVE) were also polymerized with this initiator.     

高氯酸银催化4-甲氧基苯乙烯阳离子聚合反应

采用Ph2CHCl/AgClO4作为引发体系,实现了4-甲氧基苯乙烯的阳离子聚合,探究了添加剂、聚合温度及引发剂种类对阳离子聚合的影响,并采用凝胶渗透色谱(GPC)、红外光谱(IR)和基质辅助激光解吸电离飞行时间质谱(MALDI-TOFMS)进行了表征。结果表明,聚合反应中无添加剂或使用弱的Lewis碱时,反应速度较快,产物的分子量分布较宽。使用强Lewis碱二甲基硫醚作为添加剂,反应温度为0℃,Ph2CHCl/AgClO4/Me2S物质的量比为1.0/1.0/10,反应表现出活性聚合的特征。此外,引发剂芳甲基正离子与二甲基硫醚间的作用力大小对聚合中的引发过程影响较大,二苯甲基正离子与三苯甲基正离子表现出较高的引发活性。     

Influence of polymerization conditions on the viscosity and yield of poly(phenylene sulfide ether)

High molecular weight poly(phenylene sulfide ether) (PPSE) was successfully synthesized by reaction of 4,4′‐dihydroxy diphenyl sulfide with 4,4′‐dichloro diphenyl sulfide in N‐methyl‐2‐pyrrolidone (NMP). The influence of polymerization conditions on the intrinsic viscosity and yield of PPSE was investigated and the optimized reaction condition was concluded. Reactions at about 180°C for 6 h along with sodium benzoate as an additive and monomer concentration of 0.588 mol/L NMP were found to produce the highest intrinsic viscosity (0.55 dL/g). Longer reaction time and/or higher temperature reduced the intrinsic viscosity and yield of the resulting product, probably due to side reactions, such as reductive dehalogenation and chemical degradation. X‐ray diffraction indicated that the polymer possessed of orthorhombic cell and had a high crystallinity of 65.8%. The high molecular weight PPSE is a crystalline polymer with T_m of 252°C and T_mc of 224°C. The polymer shows good chemical resistance, but is soluble in organic amide, halo‐hydrocarbon and oxohydrocarbon solvent at a temperature over 150°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Cationic polymerization using allyl sulfonium salt. 3. Allyl sulfonium salt/ascorbate redox couple

The cationic polymerization of cyclohexene oxide was initiated by reduction of allyl sulfonium salt in the presence of ascorbyl-6 hexadecanoate and copper (II) benzoate. A redox reaction in which the copper compound serving as an electron carrier for the initiation step was proposed.     

Cyclohexene oxide mid‐chain functional macromonomer of poly(ε‐caprolactone): Synthesis,characterization, and photoinitiated cationic homo‐ and copolymerization

In this study, a novel well‐defined epoxy mid‐chain functional macromonomer of poly(ε‐caprolactone) (PCL) has been synthesized by ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) and epoxidation on workup with 3‐chloroperoxybenzoic acid. The ROP of ε‐CL monomer in bulk at 110°C, by means of a dihydroxy functional initiator namely, 3‐cyclohexene‐1,1‐dimethanol in conjunction with stannous‐2‐ethylhexanoate, (Sn(Oct)₂), yielded a well‐defined PCL with a cyclohexene mid‐chain group. The epoxidation of the cyclohexene (CH) mid‐chain group of PCL was performed using 3‐chloroperoxybenzoic acid. GPC, IR, and ¹H‐NMR analyses revealed that a low‐polydispersity macromonomer of PCL with the desired cyclohexene oxide (CHO) functionality at the mid‐chain was obtained. The photoinduced cationic polymerizations of this macromonomer yielded comb‐shaped and graft copolymers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012