Spontaneous alternating copolymerization of N-phenylmaleimide with ethyl α-phenylacrylate

The spontaneous copolymerization of N-phenylmaleimide (NPMI) (M₁) with ethyl α-phenylacrylate (EPA)(M₂) were carried out in dioxane at 85°C. A high alternating tendency was observed. The monomer reactivity ratios were r₁ = 0.07 ±0.01 and r₂ = 0.09 ± 0.02. The maximum copolymerization rate and molecular weight occurs at 70–80 mol% (M₁) in feed ratio. The spontaneous alternating copolymerization is considered to be carried out via a contact-type charge transfer complex (CTC) formed between the monomers. Thermogravimetric analyses (TGA) indicate the resulting copolymers have high thermal stability. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2927–2931, 1998     

Free-radical copolymerization of styrene with N-phenyl maleimide initiated by thiol

2-Methyl–2-undecanethiol was found efficient to initiate the free-radical copolymerization of styrene (St) with N-phenyl maleimide (NPMI) at 40°C. The initial copolymerization rate increases with the increasing of thiol concentration at first, then keeps constant with the further increasing of the thiol concentration. The charge-transfer complex (CTC) formed between St and NPMI was investigated in different solvents by using ¹H-NMR. There is no definite correlation between CTC equilibrium constant, K, and the polarity of the solvent. With the increasing of CTC concentration, both the copolymerization rate and NPMI content in copolymer enhances, indicating the participation of CTC in both initiation and propagation. The monomer reactivity ratios were calculated to be r_NPMI = 0.052 and r_St ? 0.166, showing an alternating tendency for the copolymerization of St with NPMI. The molecular weight approach has shown again the effect of CTC. The function of thiol as a regulator is mitigated due to the involvement of CTC. © 1992 John Wiley & Sons, Inc.     

Synthesis of a new monomer N′‐(β‐methacryloyloxyethyl)‐2‐pyrimidyl‐(p‐benzyloxycarbonyl)aminobenzenesulfonamide and its copolymerization with N‐phenyl maleimide

The new monomer N′‐(β‐methacryloyloxyethyl)‐2‐pyrimidyl‐(p‐benzyloxy‐ carbonyl)aminobenzenesulfonamide (MPBAS) (M₁) is synthesized using sulfadiazine as parent compound. It could be homopolymerized and copolymerized with N‐phenyl maleimide (NPMI) (M₂) by radical mechanism using AIBN as initiator at 60 °C in dimethylformamide. The new monomer MPBAS and polymers were identified by IR, element analysis and ¹H NMR in detail. The monomer reactivity ratios in copolymerization were determined by YBR method, and r₁ (MPBAS) = 2.39 ± 0.05, r₂ (NPMI) = 0.33 ± 0.02. In the presence of ammonium formate, benzyloxycarbonyl groups could be broken fluently from MPBAS segments of copolymer by catalytic transfer hydrogenation, and the copolymer with sulfadiazine side groups are recovered. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2548–2554, 2000     

An alternating copolymer of maleimide and atropic acid with narrow molecular weight distribution prepared by radical mechanism

Three basic conditions for preparation of alternating copolymer with narrow molecular weight distribution were derived from the element kinetic equations of binary radical copolymerization. Using maleimide (MI) and atropie acid (ATA) as model monomer pairs and dioxane as the solvent the alternating copolymer with molecular weight distribution in the range of 1.09--1.20 was prepared successfully by charger transfer complex (CTC) mechanism in the presence of benzoyl peroxide at 85℃. The monomer reactivity ratioes r_1(MI)=0.05±0.01 and r_2(ATA)=0.03±0.02 were measured. The alternating eopolymerization was carried out through formation of a contact-type CTG and then alternating addition of MI and ATA monomers. The molecular weight of the copolymers is nearly independent of the feed ratio in a large range and the polymerization rate dropped with an increase in ATA in feed ratio.     

Polymerization of β-cyanopropionaldehyde. X. Anionic copolymerization with methyl isocyanate

Anionic copolymerization of β-cyanopropionaldehyde (M₁) with methyl isocyanate (MeI, M₂) was studied with use of benzophenone–dilithium complex as initiator at ?78°C. The values of monomer reactivity ratio were determined to be r₁ = 8.3 ± 0.3 and r₂ = 0.01 ± 0.01. The structure of resulting copolymer was investigated by means of NMR analysis. The MeI unit is presumed to enter the copolymer chain through its C?N opening.     

On the copolymerization model and microstructure of methyl acrylate - styrene radical copolymer. Influence of ZnCl2

Bulk radical copolymerization of methyl acrylate (MeA, M₁) with styrene (St, M₂) in presence and absence of ZnCl₂ as complexing agent was studied. ¹H-NMR spectra were used to establish copolymer composition and sequence distribution. The methoxy group signal was observed to be split due to pentads, but the analysis of sequence distribution is possible only at triad level. Both composition and sequence distribution data confirmed that bulk radical copolymerization respects quite well the terminal addition model; the values of r₁ = 0.14 ± 0.02 (from composition data) and r₁ = 0.25 ± 0.03 (from sequence distribution data) and r₂ = 0.83 ± 0.10 (from composition data) were found. The presence of ZnCl₂ increases the probability of alternating addition, e.g., for [ZnCl₂]/[MeA] = 0.2, r₁ = 0.03 ± 0.02 and r₂ = 0.17 ± 0.03. The radical copolymer obtained in bulk in the absence of ZnCl₂ presents a coisotactic configuration with σ = 0.75 ± 0.03, but the presence of the complexing agent reduces the probability of coisotactic addition, e.g., for [ZnCl₂]/[MeA] = 0.2, σ = 0.52 ± 0.03.     

Synthesis,Characterization, and Reactivity Ratios of Phenyl Methacrylate-N-vinyl-2-pyrrolidone Copolymers

Free radical solution copolymerization of phenyl methacrylate and N-vinyl-2-pyrrolidone was carried out using benzoyl peroxide in 2-butanone solution at 70°C. The composition of the copolymer was determined using ¹H-NMR spectra by comparing the intensities of aromatic protons to that of total protons. The results were used to calculaie the copolymerization reactivity ratios by both the Fineman-Ross (F-R) and Kelen-Tüdös (K-T) methods. The reactivity ratios are r ₁ = 4.49 ± 1.27 and r ₂ = 0.05 ± 0.09 as determined by the K-T method. These values are in good agreement with those determined by the F-R method. The FT-infrared and ¹³C-NMR spectra of the copolymer are discussed.     

Determination of the reactivity ratios of methyl acrylate with the vinyl acetate,vinyl 2,2-dimethyl-propanoate,and vinyl 2-ethylhexanoate

The course of composition drift in copolymerization reactions is determined by reactivity ratios of the contributing monomers. Since polymer properties are directly correlated with the resulting chemical composition distribution, reactivity ratios are of paramount importance. Furthermore, obtaining correct reactivity ratios is a prerequisite for good model predictions. For vinyl acetate (VAc), vinyl 2,2-dimethyl-propanoate also known as vinyl pivalate (VPV), and vinyl 2-ethylhexanoate (V2EH), the reactivity ratios with methyl acrylate (MA) have been determined by means of low conversion bulk polymerization. The mol fraction of MA in the resulting copolymer was determined by ¹H-NMR. Nonlinear optimization on the thus-obtained monomer feed–copolymer composition data resulted in the following sets of reactivity ratios: r_MA = 6.9 ± 1.4 and r_VAc = 0.013 ± 0.02; r_MA = 5.5 ± 1.2 and r_VPV = 0.017 ± 0.035; r_MA = 6.9 ± 2.7 and r_V2EH = 0.093 ± 0.23. As a result of the similar and overlapping reactivity data of the three methyl acrylate–vinyl ester monomer systems, for practical puposes these data can be described with one set of reactivity data. Nonlinear optimization of all monomer feed–copolymer composition data together resulted in r_MA = 6.1 ± 0.6 and r_VEst = 0.0087 ± 0.023. © 1994 John Wiley & Sons, Inc.     

Copolymerization of 4-cyclopentene-1,3-dione with p-chlorostyrene and vinylidene chloride

The copolymerization of 4-cyclopentene-1,3-dione (M₂) with p-chlorostyrene and vinylidene chloride is reported. The copolymers were prepared in sealed tubes under nitrogen with azobisisobutyronitrile initiator. Infrared absorption bands at 1580 cm.^?1 revealed the presence of a highly enolic β-diketone and indicated that copolymerization had occurred. The copolymer compositions were determined from the chlorine analyses and the reactivity ratios were evaluated. The copolymerization with p-chlorostyrene (M₁) was highly alternating and provided the reactivity ratios r₁ = 0.32 ± 0.06, r₂ = 0.02 ± 0.01. Copolymerization with vinylidene chloride (M₁) afforded the reactivity ratios r₁ = 2.4 ± 0.6, r₂ = 0.15 ± 0.05. The Q and e values for the dione (Q = 0.13, e = 1.37), as evaluated from the results of the vinylidene chloride case, agree closely with the previously reported results of copolymerization with methyl methacrylate and acrylonitrile and confirm the general low reactivity of 4-cyclopentene-1,3-dione in nonalternating systems.     

Comparative recalculation of the monomer reactivity ratios in copolymerization for styrene and methyl methacrylate

The monomer reactivity ratios (MMRs) in radical copolymerization for styrene and methyl methacrylate were recalculated by five different methods using literature copolymerization data. The use of approximate 95% confidence limits and their visual inspection helps to separate possibly biased copolymer composition data. The recalculated mean MRR values were r₁ (styrene) = 0.501 ± 0.031 and r₂ = 0.472 ± 0.031. The results of the linear least-squares calculation procedures seldom approach the quality of the nonlinear least-squares analysis according to the method of Tidwell and Mortimer.     

Reactivity ratios and microstructure determination of vinyl acetate–alkyl acrylate copolymers by NMR spectroscopy

(Vinyl acetate)/(ethyl acrylate) (V/E) and (vinyl acetate)/(butyl acrylate) (V/B) copolymers were prepared by free radical solution polymerization. ¹H-NMR spectra of copolymers were used for calculation of copolymer composition. The copolymer composition data were used for determining reactivity ratios for the copolymerization of vinyl acetate with ethyl acrylate and butyl acrylate by Kelen-Tudos (KT) and nonlinear Error in Variables methods (EVM). The reactivity ratios obtained are r_v = 0.03 ± 0.03, r_E = 4.68 ± 1.70 (KT method); r_v = 0.03 ± 0.01, r_E = 4.60 ± 0.65 (EV method) for (V/E) copolymers and r_v ? 0.03 ± 0.01, r_B ? 6.67 ± 2.17 (KT method); r_v = 0.03 ± 0.01, r_B = 7.43 ± 0.71 (EV method) for (V/B) copolymers. Microstructure was obtained in terms of the distribution of V- and E-centered triads and V- and B-centered triads for (V/E) and (V/B) copolymers respectively. Homonuclear ¹H 2D-COSY NMR spectra were also recorded to ascertain the existence of coupling between protons in (V/E) as well as (V/B) copolymers. © 1995 John Wiley & Sons, Inc.     

Copolymerization of n‐butylacrylate with methylmethacrylate by a novel photoinitiator, 1‐(bromoacetyl)pyrene

The photopolymerization efficiency of pyrene (Py), 1‐acetylpyrene (AP), and 1‐(bromoacetyl)pyrene (BP) for copolymerization of n‐butylacrylate (BA) with methylmethacrylate (MMA) was compared. A kinetic study of solution copolymerization in DMSO at 30 ± 0.2°C showed that the Py could not initiate copolymerization even after 20 h, whereas with AP as initiator, less than 1% conversion was observed. However, introduction of a Br in α‐methyl group of AP significantly enhanced the percent conversion. The kinetics and mechanism of copolymerization of BA with MMA using BP as photoinitiator have been studied in detail. The system follows nonideal kinetics (R_p α [BP]^0.67[BA]¹[MMA]^0.98), and degradative solvent transfer reasonably explains these kinetic nonidealities. The monomer reactivity ratios (MRRs) of MMA and BA have been estimated by the Finemann–Ross and Kelen–Tudos methods, by analyzing copolymer compositions determined by ¹H‐NMR spectra. The values of r₁ (MMA) and r₂ (BA) were found to be 2.17 and 0.44, respectively, which suggested the high concentration of alternating sequences in the random copolymers obtained. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 261–267, 2007     

Copolymerization of glycidyl methacrylate with alkyl acrylate monomers

A newer approach to obtaining acrylic thermoset polymers with adequate hydrophilicity required for various specific end uses is reported. Glycidyl methacrylate (GMA) was copolymerized with n-butyl acrylate (n-BA), isobutyl acrylate (i-BA), and 2-ethylhexyl acrylate (2-EHA) in bulk at 60°C. with benzoyl peroxide as free radical initiator. The copolymer composition was determined from the estimation of epoxy group. Reactivity ratios were calculated by the Yezrielev, Brokhina, and Roskin method. For copolymerization of GMA (M₁) with n-BA (M₂) the reactivity ratios were r₁ = 2.15 ± 0.14, r₂ = 0.12 ± 0.03; with i-BA (M₂) they were r₁ = 1.27 ± 0.06, r₂ = 0.33 ± 0.031; and with 2-EHA (M₂) they were r₁ = 2.32 ± 0.14, r₂ = 0.13 ± 0.009. The reactivity ratios were the measure of distribution of monomer units in a copolymer chain; the values obtained are compared and discussed.     

Effect of reaction medium on copolymerization of acrylonitrile and methyl acrylate

The copolymerization of acrylonitrile (AN) with methyl acrylate (MEA) has been investigated in three types of polymerization, i.e., emulsion polymerization in water with a water-soluble initiator, suspension polymerization in water with an oil-soluble and water-insoluble initiator, and solution polymerization in dimethyl sulfoxide (DMSO). Monomer reactivity ratios at 50°C. for AN and MEA are found to be r₁ = 0.78 ± 0.02, r₂ = 1.04 ± 0.02 in emulsion polymerization; r₁ = 1.02 ± 0.02, r₂ = 0.70 ± 0.02 in DMSO solution polymerization; r₁ = 0.75 ± 0.05, r₂ = 1.54 ± 0.05 in suspension polymerization. The large differences found in the reactivity ratios may be attributed to the different ratio of concentration of two monomers in the loci of polymerization. Chemically, AN is somewhat more reactive than MEA as shown by the reactivity ratios in DMSO. In the case of the suspension polymerization, the MEA/AN ratio in the polymer particles in which polymerization occurs may be higher than that in the total phase. Experimental results of the emulsion polymerization show that the emulsion polymerization of AN occurs both in the particles and in water. In addition, rates of the copolymerization of AN with MEA have also been investigated.     

Radical copolymerization behavior of a highly fluorinated cyclic olefin with vinyl ether

The copolymerization of a highly fluorinated cyclic monomer, octafluorocyclopentene (OFCPE, M₁), with ethyl vinyl ether (EVE, M₂) was investigated with a radical initiator in bulk. Despite the poor homopolymerizability of each monomer, the copolymerization proceeded successfully, and the molecular weights of the copolymers reached up to more than 10,000. Incorporation of the OFCPE units into the copolymer led to an increase in the glass‐transition point. The copolymer composition was determined from ¹H NMR spectra and elemental analysis data. The molar fraction of the OFCPE unit in the copolymer increased and approached but did not exceed 0.5. The monomer reactivity ratios were estimated by the Yamada–Itahashi–Otsu nonlinear least‐squares procedure as r_1,OFCPE = ?0.008 ± 0.010 and r_2,EVE = 0.192 ± 0.015. The reactivity ratios clearly suggest that the copolymerization proceeds alternatively in the case of an excessive feed of OFCPE. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1151–1156, 2002     

Controllability of radical copolymerization of maleimide and ethyl α‐(n‐propyl)acrylate using 1,1,2,2‐tetraphenyl‐1,2‐bis(trimethylsilyloxy) ethane as initiator

The radical copolymerization of maleimide (MI) and ethyl α‐propylacrylate was performed using 1,1,2,2‐tetraphenyl‐1,2‐bis(trimethylsilyloxy) ethane (TPSE) as initiator. The whole copolymerization process might be divided into two stages: in the first stage, the copolymerization was carried out on the common radical mechanism, the molecular weight of the copolymer increased rapidly in much lower conversion (< 85%), and did not depend on the polymerization time and conversion; in the second stage, molecular weight of the copolymer increased linearly with the conversion and the polymerization time. It was found, however, when the conversion was higher than a certain value, for example, more than 36%, the molecular weight of the copolymer was nearly unchangeable with the polymerization time and the molecular weight distribution was widened. The effect of reaction conditions on copolymerization was discussed and the reactivity ratios were calculated by the Kelen–Tudos method, the values were r_MI = 0.13 ± 0.03, r_EPA = 0.58 ± 0.06 for TPSE system and r_MI = 0.12 ± 0.03, r_EPA = 0.52 ± 0.06 for AIBN system. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2872–2878, 2000     

Alternating Copolymerization of Styrene and N-(4-Bromophenyl)Maleimide

Abstract

Free radical copolymerization of styrene (St) and N(4-bro-mophenyl)maleimide (4BPMI) in dioxane solution gave an alternating copolymer in all proportions of feed comonomer compositions. The monomer reactivity ratios were found to be r ₁, = 0.0218 ± 0.0064 (St) and r ₂, = 0.0232 ± 0.0112 (4BPMI), and the activation energy of the copolymerization reaction for the equimolar ratios of comonomer was E _a, = 51.1 kJ/mol. The molecular weights of the copolymers obtained are relatively high, the T _g's showed similar values (490 K), and the thermal stability is higher than that of polystyrene. The initial rate of copolymerization depends on the total concentration of the comonomers and the maximum occurred at higher 4BPMI mol fractions; however, the overall conversion is highest at equimolar comonomer composition. It has been shown that a charge-transfer complex participates in the process of copolymerization. The initial reaction rate was measured as a function of the monomer molar ratios, and the participation of the charge-transfer complex monomer and the free monomers was quantitatively estimated.     

Copolymerization of isopropenyl and isopropylidene oxazolones with styrene

2-Isopropenyl-4-isopropyl-2-oxazolin-5-one (M₂), was copolymerized with styrene (M₁), and the monomer reactivity ratios were determined to be r₁ = 0.31 ± 0.03, r₂ = 1.12 ± 0.10. New isomerized oxazolones (M₂), 2-isopropylidene-4-methyl-3-oxazolin-5-one, 2-isopropylidene-4-isopropyl-3-oxazolin-5-one, and 2-isopropylidene-4-isobutyl-3-oxazolin-5-one were prepared and copolymerized with styrene. The monomer reactivity ratios were: r₁ = 0.36 = 0.07, r₂ = 0.0; r₁ = 0.39 ± 0.06, r₂ = 0.00 ± 0.10; r₁ = 0.39 ± 0.10, r₂ = 0.0, respectively. The isomerized oxazolones showed no tendency towards homopolymerization by radical initiator. From the results of infrared and NMR spectra and hydrolysis of the copolymer, it was indicated that the isomerized oxazolones participated in copolymerization in the form of 1–4 polymerization of the conjugated dienes (exo double bond at C₂ and the C?N in the ring). Copolymers reacted with nucleophilic reagents such as amines and alcohols.     

Photosensitized copolymerization of optically active N-l-menthylmaleimide with styrene and methyl methacrylate

Photosensitized copolymerization of optically active N-l-menthylmaleimide (NMMI) with styrene (Sty) and methyl methacrylate (MMA) was carried out in tetrahydrofuran (THF) at 30°C with benzoyl peroxide (BPO). The monomer reactivity ratios for the copolymerization of NMMI (M₂) with Sty (M₁) and MMA (M₁) were r₁ = 0.08 ± 0.10, r₂ = 0.20 ± 0.05 and r₁ = 2.85 ± 0.06, r₂ = 0.07 ± 0.06, respectively. Copoly-MMA–NMMI and poly-NMMI showed positive circular dichroism(CD) curves of equal intensity and shape over the wavelength region from 230 to 270 nm; copoly-Sty–NMMI also showed a positive CD curve which was similar in shape but was different in intensity from that of poly-NMMI. The correlation between monomer unit ellipticity of the copolymers and their composition would suggest the alternating and stereoregular copolymerization of NMMI with Sty.