Design of new polymer architectures by combination of anionic and cationic living polymerization techniques

The grafting of polystyryl lithium onto poly(chloroethyl vinyl ether) chains has been investigated. The reaction proceeds cleanly and quantitatively thus allowing the synthesis of comblike polymers. Since the dimensions of the polystyrene branches and of the poly(chloroethyl vinyl ether) backbone can be controlled by living polymerizations, both the length and the number of branches of the graft copolymers can be tuned. The latter behave as star polymers. The possibility to initiate a new cationic polymerization of chloroethyl vinyl ether from polystyrene branches bearing acetal termini in order to prepare the corresponding stars with poly(chloroethyl vinyl ether-b- styrene) branches is also examined. Finally access to hyperbranched polymers of controlled architecture and dimensions by deactivation of a second amount of polystyryl lithium onto the last blocks of poly(chloroethyl vinyl ether) is also reported.     

The stereoregularity of polystyrenes obtained by different ion pairs of polystyryl alkali salts

The stereoregularity of polystyrenes obtained with sodium, potassium, rubidium, and cesium naphthalenes in various solvents was determined by ¹³C-NMR spectroscopy. Polystyrenes produced by contact ion pairs of polystyryl cesium in dioxane and tetrahydrofuran (THF) had the proportions of a 57–58% racemic dyad (P_r), whereas the P_r values increased to 65 and 69% by solvating Cs⁺ counterions in dimethoxyethane and by agent-separating them with crown ether, respectively. Polystyrene obtained by contact ion pairs of polystyryl sodium in dioxane showed a P_r of 66%; polymers produced by solvent-separated ion pairs of polystyryl sodium in THF at ?78°C had a P_r of 71%. A polymerization system which contained alkali counterions with large ionic radii and solvents with low dielectric constants in which only contact ion pairs existed produced polystyrenes with isotactic-rich configurations. The stereoregularity of polystyrene produced by contact ion pairs of polystyryl potassium and rubidium in tetrahydropyran (THP) occurred intermediately between that of polymers obtained in diethyl ether and THF. It was concluded that the stereoregulation of contact ion pairs may be closely related to the interionic distance of the ion pair.     

Block copolymerization. VI. Polymerization of pivalolactone with macromolecular initiators from polystyrene and polytetrahydrofuran

Polymerization of pivalolactone with polystyryl sodium or polystyryl ethoxysodium in tetrahydrofuran resulted in homopolymer mixtures. Block copolymers of pivalolactone and styrene were obtained by the polymerization of pivalolactone with sodium polystyrene carboxylate in tetrahydrofuran containing dimethyl sulfoxide. Block copolymers of pivalolactone and tetrahydrofuran were obtained by the polymerization of pivalolactone with polytetrahydrofuran containing carboxylate endgroups. The mechanism of the initiation reaction and various factors affecting block efficiency are discussed.     

Solution Properties of Star-Shaped Polystyrenes Having Peripheral Charged Ions

Functionalized polystyrene stars were prepared by copolymerization of polystyryl lithium with divinylbenzene in a mixture of benzene/tetrahydropyran, where the polystyrene arms were prepared by anionic polymerization using [2-[(N,N-dimethylamino)-methyl]phenyl]lithium as the initiator. These functional stars were converted by quaternization with methyl iodide into polystyrene stars having peripheral positive charges. We studied the charge effects on the solution properties of such stars. The hydrodynamic dimension of peripheral charged polystyrene (PS) stars depended strongly on the solubility parameter between PS segments and solvent. Copyright 2000 Academic Press.     

Synthesis of polymers containing conjugated dienyl end-groups by means of anionic living polymerization

In order to synthesize end-functionalized polymers with conjugated dienyl groups, living polymeric anions of polystyrene and polyisoprene were allowed to react with 5-bromo-1,3-pentadiene, 1, and 7-bromo-1,3-heptadiene, 2. The reaction of polystyryl anion and/or polyisoprenyl anion with 1 gave polymers whose end-functionalities were 65–80% regardless of the reaction conditions. On the other hand, almost quantitative functionalization was achieved when a large excess amount of 2 was used as a terminator. When 1,1-diphenylalkyl anion and enolate anion derived from t-butyl methacrylate were used, the degree of end-functionality were 70–80% at best. The resulting end-functionalized polymers were characterized by size exclusion chromatography (SEC), ¹H and ¹³C-NMR and thin layer chromatography coupled with a flame ionization detector (TLC-FID). © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3464–3472, 1999     

The photo-oxidation of diethyl ether in smog chamber experiments simulating tropospheric conditions: Product studies and proposed mechanism

The products formed by the hydroxyl radical initiated photo-oxidation of diethyl ether have been investigated by irradiating synthetic air mixtures containing diethyl ether and nitrous acid in amounts approaching ppbv levels in a smog chamber. The decay of reactants and formation of products were monitored by gas chromatography, HPLC, and by chemiluminescent analysis. The major products are ethyl formate and formaldehyde, minor products include ethyl acetate, acetaldehyde, peroxyacetyl nitrate, methyl nitrate, and ethyl nitrate. The products observed arise from the decomposition reactions of the 1-ethoxyethoxy radical and its reaction with oxygen. One molecule of nitric oxide appears to be oxidized per molecule of diethyl ether reacted. This is lower than would be expected on the basis of the proposed mechanism and possible reasons for the discrepancy are discussed. © 1993 John Wiley & Sons, Inc.     

A TEMPO-mediated “living” free-radical approach to ABA triblock dendritic linear hybrid copolymers

Dumbbell-shaped ABA triblock copolymers composed of benzyl ether dendrons and polystyrene as the A and B blocks, respectively, were prepared using 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO) -mediated “living” free-radical polymerization. A new bis-dendritic unimolecular initiator, compound 3, was employed to study the efficiency of ABA triblock formation under standard TEMPO-mediated polymerization conditions. By this design, the central B block of the ABA triblock copolymer was grown into the bis-dendritic unimolecular initiator. The ABA triblock copolymer products were separated from their by-products, AB diblock copolymers, by column chromatography on silica gel. The isolated copolymers were characterized using gel permeation chromatography and proton nuclear magnetic resonance spectroscopy as complimentary techniques. That the dendritic-linear AB diblock copolymer was obtained in a mixture with ABA triblock material indicates that TEMPO-terminated dendron counter-radical 5 is an imperfect mediator of this free-radical polymerization. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3748–3755, 1999     

One‐pot preparation of ABA‐type block‐graft copolymers via a combination of “click” chemistry with atom transfer nitroxide radical coupling reaction

A new strategy for the one‐pot preparation of ABA‐type block‐graft copolymers via a combination of Cu‐catalyzed azide‐alkyne cycloaddition (CuAAC) “click” chemistry with atom transfer nitroxide radical coupling (ATNRC) reaction was reported. First, sequential ring‐opening polymerization of 4‐glycidyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl (GTEMPO) and 1‐ethoxyethyl glycidyl ether provided a backbone with pendant TEMPO and ethoxyethyl‐protected hydroxyl groups, the hydroxyl groups could be recovered by hydrolysis and then esterified with 2‐bromoisobutyryl bromide, the bromide groups were converted into azide groups via treatment with NaN₃. Subsequently, bromine‐containing poly(tert‐butyl acrylate) (PtBA‐Br) was synthesized by atom transfer radical polymerization. Alkyne‐containing polystyrene (PS‐alkyne) was prepared by capping polystyryl‐lithium with ethylene oxide and subsequent modification by propargyl bromide. Finally, the CuAAC and ATNRC reaction proceeded simultaneously between backbone and PtBA‐Br, PS‐alkyne. The effects of catalyst systems on one‐pot reaction were discussed. The block‐graft copolymers and intermediates were characterized by size‐exclusion chromatography, ¹H NMR, and FT‐IR in detail. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Cationic and pseudocationic polymerization of aromatic olefins—III. [1a.b]: A re-investigation of the polymerization of styrene by perchloric acid in methylene dichloride

A reinvestigation of the polymerization of styrene by perchloric acid in methylene dichloride at 0° with improved techniques has shown that the polymerizations are not of first order throughout; after the first half-life, the reaction accelerates and the electrical conductivity of the reaction mixture increases concurrently. These phenomena are ascribed to the slow ionization of the propagating polystyrylperchlorate ester to much more rapidly propagating polystyryl ions present in very low concentrations, and in equilibrium with a much larger concentration of non-propagating polystyrylindanyl ions. Our observations, together with those of other authors on the bimodal DP distribution of polystyrenes formed under similar conditions, confirm that the pseudocationic polymerization propagated by the polystyryl perchlorate ester is indeed a distinct form of reaction.     

Microwave-assisted extraction for qualitative and quantitative determination of brominated flame retardants in styrenic plastic fractions from waste electrical and electronic equipment (WEEE)

A fast method for the determination of brominated flame retardants (BFRs) in styrenic polymers using microwave-assisted extraction (MAE) and liquid chromatography with UV detection (HPLC-UV) was developed. Different extraction parameters (extraction temperature and time, type of solvent, particle size) were first optimised for standard high-impact polystyrene (HIPS) samples containing known amounts of tetrabromobisphenol A (TBBPA) and decabromodiphenyl ether (Deca-BDE). Complete extraction of TBBPA was achieved using a combination of polar/non-polar solvent system (isopropanol/n-hexane) and high extraction temperatures (130 °C). Lower extraction yields were, however, obtained for Deca-BDE, due to its high molecular weight and its non-polar nature. The developed method was successfully applied to the screening of BFRs in standard plastic samples from waste electrical and electronic equipment (WEEE); TBBPA could be fully recovered, and Deca-BDE could be identified, together with minor order polybrominated diphenyl ether (PBDE) congeners.     

Studies on and with Functionalized Polystyrenes

A number of useful functionalized polystyrenes have been prepared. Studies on fluoroalkyl ketone, fluoroalkyl carbinol, and hydroxy-contain polystyrenes, as well as polystyryl pyridine-based polymers, in regard to a variety of properties were made. These are discussed individually in regard to their reactions with alcohols to form hemiketals, miscibilization by hydrogen bonding, improvements in the thermostability of blends, and char formation at elevated temperature, respectively. In addition, enhancements of polystyrene and copolymers of modified polymers in regard to the oxidative stabilization of blends are discussed.     

聚苯乙烯-二苯基膦-铜(Ⅰ)-四氢化硼络合物的制备及其对酰氯的还原

以不同交联度(1%, 2%, 4%, 7%, 8%, 12%)的聚苯乙烯树脂为支载体, 制备了聚苯乙烯-二苯基膦-铜-四氢化硼络合物, 对它们的容量和结构进行了测试和分析, 并研究了该络合物在不同温度、溶剂、催化剂下, 对苯甲酰氯, 肉桂酰氯, 对硝基苯甲酰氯的还原性能以及其回收再生后的重复使用情况。     

The study of macronet isoporous styrene polymers by gel permeation chromatography

Gel permeation chromatography was used for studying the structure of macronet isoporous styrene polymers swollen in chloroform. The polymers were obtained by crosslinking polystyrene either in a solution or in a swollen state using monochlorodimethyl ether and p-xylylenedichloride via the Friedel–Crafts reaction. It is shown that the networks obtained by structurization of concentrated polystyrene solution in a good solvent are characterized by loose structure, fine pores (ca. 10 Å), and narrow pore distribution. In poor solvents or in strong dilution of polystyrene and at the instant of net formation, the polymers that are obtained contain, in addition to fine pores, large pores with diameters up to 300 Å.     

Reactions of polystyryl anions with carbon dioxide and oxygen. Analysis of products by silica gel chromatography

Polystyryllithium was prepared by anionic polymerization. This “living polymer” and the polystyrylmagnesium bromide derived from it were treated with carbon dioxide (solid or gas). The highest yields of carboxylic acid were obtained when solid carbon dioxide was used with polystyryllithium or by treatment of polystyrylmagnesium bromide with gaseous carbon dioxide. The products from the reaction of polystyryllithium with oxygen were polymeric ketone X, the alcohols IXa and IXb, and coupling products (e. g., XI). The various functionalized and unfunctionalized polystyrene products were isolated by chromatography on silica gel and were characterized by gel permeation chromatography (GPC), thin layer chromatography (TLC), and high-performance liquid chromatography (HPLC) in combination with chemical transformations.     

Thermal degradation of copolymers of styrene and acrylonitrile. II. Reaction products

Hydrogen cyanide is a minor product of degradation of copolymers of styrene and acrylonitrile. The liquid products have been separated and identified by combined gas chromatography and mass spectrometry (GC-MS), as styrene, acrylonitrile, toluene, and benzene. The ratio of styrene to acrylonitrile monomers in the products is approximately twice that of the monomer units in the copolymers, and the ratios of styrene to toluene and benzene are the same as are obtained from pure polystyrene. These ratios were determined by using infrared spectral methods. The fraction of products volatile at the temperature of degradation but involatile at ambient temperature was also analyzed by using GC-MS. A series of four dimers and four trimers were fairly reliably identified. The residual material from copolymers containing up to 33.4% acrylonitrile is always soluble in toluene. The 50/50 copolymer and its residues are insoluble in toluene. Yellow coloration develops in the residues from high acrylonitrile copolymers at advanced stages of degradation. Infrared and ultraviolet spectra suggest that this is due to conjugated unsaturation in the polymer chain backbone which may be associated with the liberation of hydrogen cyanide from the acrylonitrile units.     

Capillary gas chromatographic analysis of volatile and non-volatile organic acids from biological samples as the t-butyldimethylsilyl derivatives

A quantitative procedure for the analysis of volatile organic acids and lactic acid in silage is described. The samples were extracted with diethyl ether, derivatized by t-butyldimethylsilylation, and then separated by capillary gas chromatography. The same procedure was useful for the identification by gas chromatography/mass spectrometry of organic acids in samples such as the metabolic fermentation products of anaerobic bacteria.     

Copolymerization of styrene and acrylonitrile with functional silanes

Styrene has been copolymerized to high conversions with vinylmethyl diacetoxysilane (VMDAS) and vinylmethyldiethoxysilane (VMDES) in bulk and in toluene at 60 using azobisisobutyronitrile (AIBN) as initiator. Acrylonitrile has also been copolymerized with VMDAS at 50 in bulk using AIBN. The compositions of the copolymers were determined from the silicon contents; reactivity ratios were calculated by the Kelen-Tüdös method. The reactivity ratio r₁ (styrene) is higher for styrene-VMDES than for styrene-VMDAS, indicating higher reactivity of VMDAS towards polystyryl radical. VMDAS was found to be more reactive towards the polyacrylonitrile than towards the polystyrene radical. The influences of the silicon comonomer on properties such as intrinsic viscosity, solubility, molecular weight distribution and thermal behaviour were also studied.     

含砜功能基的交联聚苯乙烯的红外光谱特性

本文合成了一系列聚苯乙烯基支载的含砜基的化合物X=Cl,O(CH_2)_9CH_3,NH_2,NHNH_2,Na,CH_2CH_3,OH)并较系统地研究了这些聚合物中的=SO_2基团的红外光谱特性,比较了聚合物和低分子类似物的特征吸收频率的变化规律,考察了聚合物骨架对S=O基团的虹外吸收峰的影响。     

Etude de la polymerisation anionique du styrene en milieu non polaire,en presence de N,N,N′,N′ tetramethyl ethylene diamine

A kinetic study was performed for the polymerization of styrene initiated by polystyryl Li oligomers with TMEDA in cyclohexane solution; the influences of r = (TMEDA)/(polystyryl Li), active species concentration and temperature, were established. The kinetic orders show, with spectrophotometric considerations, that the polymerization is mainly propagated by the species polystyryl, Li, TMEDA, the reactivity of which is lower than that of polystyryl Li non-aggregated. The result is that, depending on the concentration of active centres, TMEDA can increase or decrease the overall reactivity of the system.     

Chromatographic analysis, isolation and partial characterization of two photocatalysed reaction products of haem and quinone

Quinone was reacted in vitro with free haem under ultraviolet light. Two principal products were detected by liquid chromatography and purified by column chromatography. Mass spectral and Fourier transform infrared analyses showed that both products contained pyrroles and that the first product was probably an ether formed after reaction with the haem vinyl moieties. This product was entirely different from the known N-alkyl intermediates in the haem-catalysed epoxidation reactions of porphyrin dimerization by quinone.