Copolymerization of 2-chloro-N,N-dimethylacrylamide

2-Chloro-N,N-dimethylacrylamide (CNA) does not homopolymerize easily (2% after 12 days) in contrast to 2-chloroacrylic esters. Its copolymerization with styrene (St) and methyl methacrylate (MMA) is governed by the following copolymerization parameters: r_CNA = 0,03 and r_MMA = 3,4; r_CNA = 0,2 ± 0,05 and r_St = 1,5 ± 0,2. The very low rates of copolymerization and the low molecular weights of the copolymers are interpreted on the basis of the formation of sterically hindered resonance stabilized radicals, and of high chain transfer constants.     

Analysis of the linear methods of determining copolymerization reactivity ratios, 12. Copolymerization of styrene or methyl methacrylate with N-p-tolylcitraconimide or fumarodinitrile

For copolymerization of styrene or methyl methacrylate with N-p-tolylcitraconimide (in toluene) or fumarodinitrile (in benzene) at 60°C with 2,2′-azoisobutyronitrile (AIBN) as initiator, the composition of the resulting copolymers was measured as a function of the monomer feed composition. To provide good accuracy of reaction modelling in terms of the terminal and penultimate models, the linearized forms of both models were applied assuring high sensitivity of the evaluation. Among the systems considered the styrene/fumarodinitrile system with r′₁/r′₁ ≈ 10 was found to copolymerize according to the penultimate mechanism to a significant degree.     

Radical Copolymerization Behavior of 2,2‐Dimethyl‐5‐methylene‐1,3‐dioxolan‐4‐one with Common Monomers

Radical copolymerization of 2,2‐dimethyl‐1,3‐dioxolan‐4‐one (DMDO) consisting of a hybrid structure of acrylate and vinyl ether moieties with styrene, methyl methacrylate, and vinyl acetate was examined. The radical copolymerization was carried out without a solvent or in chlorobenzene in the presence of 3 mol‐% of 2,2′‐azoisobutyronitrile at 60°C for 20 h to obtain the copolymers with number‐average molecular weights of 1 400‐700 000 in 27–86% yields. No ring‐opening occurred but vinyl polymerization of DMDO selectively proceeded in the copolymerization. The monomer reactivity ratios were evaluated as r₁ = 6.42, r₂ = 0.08 (M₁, DMDO; M₂, styrene) by the Fineman‐Ross method. The Alfrey‐Price Q‐ and e‐values of DMDO were calculated as 5.97 and –0.13, respectively. Ab initio molecular orbital calculations were carried out to compare the reactivity of DMDO with methyl α‐methoxyacrylate and vinyl ether.     

Free-radical polymerization of methyl methacrylate initiated by N,N-dimethylaniline

N,N-Dimethylaniline (DMA) does initiate the free-radical polymerization of methyl methacrylate (MMA), methyl acrylate, and methyl vinyl ketone. The overall rates of polymerization of MMA were obtained at 40, 50, and 60°C. From the results of a detailed kinetic investigation, the activation enthalpy and activation entropy of polymerization were calculated as 63,2 kJ mol^?1 and ?153 J mol^?1 K^?1 at 60°C. Rate equation was also obtained as R_p = k[DMA]^1/2[MMA]^3/2 and the polymerization was inhibited by benzoquinone. Though styrene alone was not polymerized by DMA, the copolymerization of MMA with styrene by DMA (reactivity ratios: r_MMA=0,45 and r_St=0,50) followed a typical free-radical mechanism. An electron-transfer complex between DMA and MMA is proposed as the initiation species.     

Über copolymere der p-vinylbenzolboronsäure mit styrol

The reactivity ratios of the radical solution copolymerization for the systems p-vinylbenzeneboronic acid ( 1a ) (M₁)/styrene, resp. bis(trimethylsilyl) p-vinylbenzeneboronate ( 1b ) (M₁)/styrene were determined by means of boron analyses:

• 1a: r₁=0,28±0,06 and r₂=0,83±0,04
• 1b: r₁=0,28±0,10 and r₂=0,87±0,08

By cleavage of the trimethylsilyl groups, the 1b /styrene copolymers are smoothly transformed into 1a /styrene copolymers. The lithium, sodium, and potassium salts of some copolymers were prepared. The solution viscosities of the polymeric boronic acids in benzene/methanol mixtures and in dimethyl sulfoxide (DMSO) markedly depend on the boronic acid content. In benzene/methanol mixtures the preferential solvatation of the boronic acid groups by methanol can be ascertained. Further, the introduction of boronic acid groups in polystyr-enecorresponds with an increase of theglass transition temperature. The torsion pendulum measurements show that the pressure-molding of the polymers causes the formation of crosslinks, which are boronic acid anhydrides. These crosslinks can be cleaved by protic solvents.     

Die thermische polymerisation von methylmethacrylat, 3. Verhalten des ungesättigten dimeren bei der polymerisation

The thermal polymerization of methyl methacrylate is accompanied by the formation of appreciable amounts of an unsaturated dimer (H-1). The behaviour of H-1 during homopolymerization in presence of an initiator at 60, 80 and 100°C and during copolymerization with MMA in presence of an initiator at 60°C are investigated. The rate of (H-1)-homopolymerization is very low. The transfer constant to monomer H-1 is about C_H-1 = 3·10^?3 at 80°C as received from P_n-determinations. The termination is essentially by disproportionation. The copolymerization parameters as resulting from polymerizations with labeled MMA at 60°C are r_MMA = 1,8 and r_H-1 = 0,33, respectively.     

Darstellung und polymerisationsverhalten von einigen neuen vinylverbindungen

4-Vinylbenzophenone anile is prepared from 4-vinylbenzophenone and aniline. In contrast to 4-vinylbenzophenone, it can be polymerized up to high conversions without crosslinking. From IR-spectroscopic analysis of the copolymers prepared radically at 60°C from styrene and 4-vinylbenzophenone anile, the following copolymerization reactivity ratios result: r₁ = 1.88 ± 0.08 (4-vinylbenzophenone anile) and r₂ = 0.36 ± 0.02 (styrene). Vinyl-α.α-diphenylethylene is obtained from methylmagnesium. iodide and 4-vinybenzophenone. Polymerization as well as copolymerization with styrene takes place not only via the vinyl group but also via the vinylidene group ; the rather low-molecular polymers which are formed still contain free vinyl groups. 4-Vinyl-4′-dimethylaminoazobenzene (prepared by diazotation of 4-aminostyrene and subsequent coupling with dimethyl aniline) does not undergo radical polymerization; it does, however, copolymerize with styrene. In this case, the rate of polymerization increases with decreasing content of 4-vinyl-4′-dimethylaminoazobenzene. The copolymerization reactivity ratios of this system can hence only be approximated. 4-Vinyltriaryl carbinols can be prepared in yields of 50 to 70 % from 4-vinyl-phenylmagnesium chloride and aryl ketones. 4-Vinyl-4′-phenyltriphenyl carbinol and 4-vinyl-4′.4″-diphenyltriphenyl carbinol can be polymerized radically in bulk as well as in benzene solution. Insoluble, completely cross-linked polymers are formed in bulk polymerization. In benzene solution at low conversions, soluble polymers are obtained with degrees of polymerization of 300 to 350. Dilatometric measurements show that the polymerization rates of the 4-vinyltriarylcarbinols are substantially greater than that of styrene. The 4-vinyltriarylmethyl chlorides, which are accessible via the corresponding 4-vinyl-triaryl carbinols with acetyl chloride, can be neither homopolymerized nor copolymerized with styrene since the triarylmethyl chloride groups inhibit radical polymerization.     

Radically initiated polymerization of a methacryloylamido-terminated saccharide, 2. Copolymerization with 2-hydroxyethyl methacrylate

Kinetics of radically initiated copolymerization of 6-deoxy-6-methacryloylamido-D -glucopyranose (MAG) with 2-hydroxyethyl methacrylate (HEMA) was investigated at 60°C in water using 4,4′-azobis(4-cyanopentanoic acid) as initiator. Reactivity ratios of the binary system were determined to be r_HEMA = 3.50 and r_MAG = 0.60, indicating a strong copolymerization drift as polymerization proceeds. Copolymers with homogeneous composition were prepared using a simple and easy method based on the knowledge of the consumption rate of each monomer. These copolymers were then characterized with regard to composition (by ¹H NMR) and physicochemical properties in aqueous media (using SEC with MALLS and refractometry detection and viscosimetric measurements).     

Copolymerization and copolymers of N-(2,4,6-tribromophenyl)maleimide with methyl acrylate and methyl methacrylate

N-(2,4,6-Tribromophenyi)maleimide (TBPMI) was copolymerized with methyl acrylate (MA) or methyl methacrylate (MMA) in toluene solution using 2,2′-azoisobutyronitrile as free-radical initiation. The copolymerization reactivity ratios were found to be for the system TBPMI/MA r₁ = 0,095 ± 0,045 (TBPMI) and r₂ = 2,17 ± 0,142 (MA) and for the system TBPMI/MMA r₁ = 0,037 ± 0,042 (TBPMI) and r₂ = 4,32 ± 0,230 (MMA); Q and e values were also calculated. The initial rate of copolymerization, R_p, for TBPMI/MA sharply decreases as the content of TBPMI in the monomer mixture increases but the composition of the feed does not have a strong influence on R_p for the TBPMI/MMA copolymerization system. The course of copolymerization to high conversion is characterized by an increase of conversion up to a mole fraction of TBPMI of 0,7 in the monomer mixture, when MA was used as the comonomer. An opposite behaviour was found with MMA. Its copolymers show a considerable increase of thermal stability as well as of the glass transition temperatures with increasing TBPMI content.     

Polymere aus 6-Acryloylamino-2,3-diphenylchinoxalin

6-Acryloylamino-2,3-diphenylquinoxaline ( 5a ) and 6-methacryloylamino-2,3-diphenylquinoxaline ( 5b ) are synthesized by condensation of 6-amino-2,3-diphenylquinoxaline ( 3 ) with the corresponding acyl chlorides. The radical polymerization of 5a in dioxane at 60°C yields polymers with softening points of 270–280°C. The degrees of polymerization are relatively low. 5a is copolymerized radically with methyl methacrylate. The copolymerization parameters under the above mentioned polymerization conditions are r₁=3,09 ( 5a ) and r₂=0,89 (methyl methacrylate). Monomers and polymers are characterized by their IR-, NMR-, and UV-spectra.     

Graft copolymers of poly(methyl methacrylate) and polythiophene

2-(2-Thienyl)ethyl methacrylate (2TEMA, 1 ), 2-(3-thienyl)ethyl methacrylate (3TEMA,2) and 2-(N-pyrrolyl)ethyl methacrylate (PEMA, 3 ) were synthesized and copolymerized with methyl methacrylate (MMA) by radical initiation with AIBN. The reactivity ratios for the system MMA/2TEMA were determined to be r_MMA = 0,57 ± 0,09 and r_2TEMA = 0,90 ± 0,03. Thiophen was grafted into the copolymers from 1 – 3 via oxidative polymerization in nitromethane. The graft copolymers were soluble as aggregates, and films cast from these solutions reached conductivities in the range of 0,2 to 0,4 S/cm.     

Free radical copolymerization of butadiene and vinylferrocene

The free radical copolymerization of butadiene and vinylferrocene was studied at 60°C in 1,4-dioxane. Copolymerization occurs readily to give low molecular weight random copolymers. The reactivity ratios are r₁ (butadiene) = 3,5±0,5 and r₂ (vinylferrocene) = 0,30±0,10 and the Q and e values for vinylferrocene are 0,68 and ?1,05, respectively. The copolymers are shown to contain a paramagnetic species which is identified as a high spin Fe(III) complex.     

Copolymerization of styrene with α-chloromaleic anhydride, 1. Mechanism of the radical-initiated copolymerization in 1,4-dioxane

The radical-initiated copolymerization of styrene (ST) with α-chloromaleic anhydride (CMA) in 1,4-dioxane was investigated. The formation of a 1:1 charge transfer (CT) complex between the comonomers in 1,4-dioxane at 25°C was confirmed by UV-spectroscopic studies, and the formation constant was found to be near zero, indicating that the complex is of contact type. An alternating copolymer was obtained by copolymerization over a relatively wide range of feed composition, and the monomer reactivity ratios, r_ST and r_CMA, were found to be 0,07 and 0,00, respectively, at 60°C. The copolymerization at a constant total monomer concentration showed a maximum rate at a styrene mole fraction of 0,4 in the feed. The copolymerization was interpreted by a consecutive monomer addition mechanism without taking into account a participation of the CT complex in the propagation.     

Copolymerization of cycloalkenes with ethylene in presence of chiral zirconocene catalysts

The chiral catalyst ethylene(bisindenyl)zirconiumdichloride/methylaluminoxane, which is soluble in hydrocarbons, allows the polymerization of cyclic alkenes, e. g. cyclopentene, to form isotactic polymers. No ring opening reaction occurs. To reduce the high melting point of the polycyclopentene, copolymers with ethylene were synthesized. The copolymerization of cyclopentene with ethylene shows similar reaction rates as found for the homopolymerization of ethylene. From ¹³C NMR spectroscopically calculated rates of incorporation of cyclopentene or cycloheptene in the polymers the copolymerization parameters can be deduced. With increasing polymerization temperature from ?10 to 20°C the r₁ values rise significantly from 80 to 300. Up to 10 mol-percnt; of cyclopentene monomeric units in the polymer the comonomer is incorporated statistically, whereas a higher content of comonomer leads to two-block formation.     

Synthesis,polymerization, and copolymerization of lactams containing vinyl groups

Two new lactam monomers containing vinyl groups were synthesized, namely 1-benzyl-3-methylene-5-methyl-2-pyrrolidone ( 1 ) and 5-oxo-2-pyrrolidinylmethyl methacrylate ( 2 ). Their homopolymerization and copolymerizations with methyl methacrylate (MMA), styrene, or methylacrylate were studied. The copolymerization parameters r₁ and r₂ were also evaluated. Poly( 1 ) is a stable polymer which decomposes at ≈ 300°C under nitrogen and at 250°C in air. Its pyrrolidone ring is resistant towards acids and bases.     

Self-crosslinkable polymers, 2. High pressure copolymerization of 2,3-epoxy-1-propyl methacrylate with 2-vinyl-5-ethylpyridine

2,2′-Azoisobutyronitrile-initiated copolymerization of 2,3-epoxy-1-propyl methacrylate ( 1 ) (M₁) with 5-ethyl-2-vinyl-pyridine ( 2 ) (M₂) was studied in tetrahydrofuran at 60°C under high pressure up to 15 kbar. Under pressure, soluble linear polymers with pendant epoxy and pyridyl groups were obtained and can be used as self-curable resins. The monomer reactivity ratios, r₁ and r₂, became larger with increasing pressure (r₁, r₂, and pressure given): 0,60, 0,64 at 2 kbar; 0,64, 0,66 at 4 kbar; 0,72, 0,69 at 7 kbar; 0,78, 0,72 at 10 kbar; 0,87, 0,76 at 13 kbar; 0,91, 0,80 at 15 kbar. Therefore, the change of activation volume of the chain propagation, ΔV, may vary from one type of propagation step to another. The intrinsic viscosities of the copolymers were found in tetrahydrofuran at 30°C to be 0,26 to 1,35 and to be dependent upon the copolymer composition and the pressure. These copolymers were amorphous, had no clear melting points and became insoluble crosslinked polymers under heating without further addition of any curing agents.     

Polymerization in the presence of organoaluminum compounds and Azobisisobutyronitrile

The rate of decomposition of azobisisobutyronitrile (AIBN) in methyl methacrylate styrene, and a styrene/methyl methacrylate mixture and the rate of polymerization of the monomers are enhanced in the presence of organoaluminum halides. The monomer-R_xAlX_y interaction influences the rates of both AIBN decomposition and monomer polymerization as well as the polymerization mechanism. The copolymerization of styrene and methyl methacrylate yields alternating copolymers in the presence of AIBN/R_xAlCl_y and random copolymers in the presence of AIBN alone. The AIBN/R_xAlCl_y activated copolymerization occurs in the dark but is accelerated in visible light.     

Solvent effects on radical polymerization of cyclododecyl acrylate, 2. Copolymerization

The radical copolymerization of cyclododecyl acrylate (CDA) with styrene (St) or acrylonitrile (AN) was studied in bulk, benzene, tetrahydrofuran, or dioxane at 60°C, and was compared with that of cyclohexyl acrylate (CHA). In the copolymerization with St, the change in the ester groups or the used solvents influenced the reactivity of both acrylates in the same manner as their homopolymerization rates. Approximately, CDA and CHA behaved like methyl methacrylate in the copolymerization with St. Contrary, in the cases of copolymerization of CDA with AN, peculiar results were obtained and interpreted in terms of characteristic association states of the monomers in the solutions. In benzene solution both the monomer reactivity ratios, r₁ and r₂, are larger than unity (M₁ = AN, M₂ = CDA; r₁ = 1,7, r₂ = 2,0).     

A Combined Computational and Experimental Study on the Free‐Radical Copolymerization of Styrene and Hydroxyethyl Acrylate

Bulk free‐radical copolymerization of styrene and 2‐hydroxyethyl acrylate (HEA) is investigated experimentally at 50 °C using pulsed‐laser polymerization and computationally using ab initio simulations. Arrhenius parameters for HEA chain‐end homopropagation are A = 1.72 × 10⁷ L mol^?1 s^?1 and E_a = 16.8 kJ mol^?1, based on experiments between 20 and 60 °C. Copolymer composition data are well fitted by the terminal model with reactivity ratios r_ST = 0.44 ± 0.03 and r_HEA = 0.18 ± 0.04, but the variation in the propagation rate coefficient with monomer composition is underpredicted. Results are compared with computational predictions assuming the terminal as well as the penultimate unit effect (PUE) model. Intramolecular H‐bonding is shown to have a significant influence on PUE calculations. Discrepancies between computational predictions and experiment are attributed to the influence of intermolecular H‐bonding.     

Stabile Polyphenoxyle, 2. Polymerisationsverhalten von Monomeren mit sterisch behinderter,freier oder geschützter phenolischer Hydroxylgruppe

2,6-Di(tert-butyl)-4-vinylphenol ( 1 a ), 2,6-di(tert-butyl)-4-isopropenylphenol ( 1 b ) and 2,6-di(tert-butyl)-4-isopropenylanisol ( 1 c )can be polymerized only be cationic mechanism with proton or LEWIS acids. Free radical or anionic polymerization is impossible. 1 a polymerizes in methylene chloride at ?78°C very fast and quantitatively. ( 1 c ) polymerizes under the same conditions only up to 28%. 1 b polymerizes very slowly, yielding 1 to 3% high molecular products. In the cationic copolymerization with styrene 1a and 1b were preferentially incorporated in the copolymers (reactivity ratios: 1 a /styrene: r₁ = 3,4, r₂ = 0,046; 1 b /styren: r₁ = > 1; r₁ = 0,076). 1 a and 1 b give crosslinked homo- or copolymers if during the propagation step sec-carbonium ions are formed. In contrary, the homopolymerization of 1 c or 1 b gives polymers which are soluble in benzene. The crosslinking is caused by a chain transfer reaction of growing sec-macrocarbonium ions with hydroxylic groups of other polymer chains.