Copolymers from Castor Oil Prepolymers (COP). 4. Copolymerization of Methyl Methacrylate with COP

The copolymerization of castor oil prepolymer (COP) with methyl methacrylate (MMA) has been accomplished at 75°C using a free radical initiator. The monomer reactivity ratios of MMA (r₁) and COP (r₂) were determined to be r₁ = 3.04 and r₂ = 0.605. With an increasing concentration of COP in the binary mixture, copolymers with decreasing molecular weight were obtained. The copolymers obtained were powdery substances soluble in many organic solvents.     

Copolymers from Castor Oil Prepolymers (COP). 2. Copolymerization of Styrene with COP

A study of copolymerization of castor oil prepolymers (COP) with styrene has been made at 75°C using benzoyl peroxide as initiator. It has been found that good yields of copolymers (high molecular weight M _n = 123,989) are obtained at a low concentration of COP. With an increasing concentration of COP in the binary mixture, copolymers with decreasing molecular weight are obtained. This is explained as due to presence of a high percentage of oxygen (from COP) in the system which is acting as a chain transfer agent.     

Hydrophilic and hydrophobic copolymer systems based on acrylic derivatives of pyrrolidone and pyrrolidine

This article deals with the synthesis of hydrophilic methacrylic monomers derived from ethyl pyrrolidone [2‐ethyl‐(2‐pyrrolidone) methacrylate (EPM)] and ethyl pyrrolidine [2‐ethyl‐(2‐pyrrolidine) methacrylate (EPyM)] and their respective homopolymers. For the determination of their reactivity in radical copolymerization reactions, both monomers were copolymerized with methyl methacrylate (MMA), the reactivity ratios being calculated by the application of linear and nonlinear mathematical methods. EPM and MMA had ratios of r_EPM = 1.11 and r_MMA = 0.76, and this indicated that EPM with MMA had a higher reactivity in radical copolymerization processes than vinyl pyrrolidone (VP; r_VP = 0.005 and r_MMA = 4.7). EPyM and MMA had reactivity ratios of r_EPyM = 1.31 and r_MMA = 0.92, and this implied, as for the EPM–MMA copolymers, a tendency to form random or Bernoullian copolymers. The glass‐transition temperatures of the prepared copolymers were determined by differential scanning calorimetry (DSC) and were found to adjust to the Fox equation. Total‐conversion copolymers were prepared, and their behavior in aqueous media was found to be dependent on the copolymer composition. The swelling kinetics of the copolymers followed water transport mechanism case II, which is the most desirable kinetic behavior for a swelling controlled‐release material. Finally, the different states of water in the hydrogels—nonfreezing water, freezing bound water, and unbound freezing water—were determined by DSC and found to be dependent on the hydrophilic and hydrophobic units of the copolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 395–407, 2003     

Copolymerization of 4‐Propanoylphenyl Acrylate with Methyl Methacrylate: Synthesis,Characterization and Reactivity Ratios

The new acrylic monomer 4‐propanoylphenyl acrylate (PPA) was synthesized and copolymerized with methyl methacrylate (MMA) in methyl ethyl ketone at 70±1°C using benzoyl peroxide as a free radical initiator. The copolymers were characterized by FT‐IR, ¹H‐NMR and ¹³C‐NMR spectroscopic techniques. The compositions of the copolymers were determined by ¹H‐NMR analysis. The reactivity ratios of the monomers were determined using Fineman‐Ross (r₁=0.5535 and r₂=1.5428), Kelen‐Tüdös (r₁=0.5307 and r₂=1.4482), and Ext. Kelen‐Tüdös (r₁=0.5044 and r₂=1.4614), as well as by a nonlinear error‐in‐variables model (EVM) method using a computer program, RREVM (r₁=0.5314 and r₂=1.4530). The solubility of the polymers was tested in various polar and non‐polar solvents. The elemental analysis was determined by a Perkin‐Elmer C‐H analyzer. The molecular weights (M_w and M_n) of the copolymers were determined by gel permeation chromatography. Thermogravimetric analysis of the polymers reveals that the thermal stability of the copolymers increases with an increase in the mole fraction of MMA in the copolymers. Glass transition temperatures of the copolymers were found to increase with an increase in the mole fraction of MMA in the copolymers.     

Copolymers of vinyl chloride and vinylidene chloride with some acid chlorides

Vinyl chloride and vinylidene chloride were copolymerized with 10-acryloxydecanoyl chloride and 12-acryloxystearoyl chloride by use of free-radical initiator in solution to obtain copolymers with active chlorine groups. Alternative routes for making such copolymers which consisted of making the corresponding acrylic acid or acrylyl chloride copolymers, followed by reaction with hydroxy acid and finally conversion to the acid chloride by treatment with thionyl chloride, were investigated. The monomer reactivity ratios for the radical copolymerization of vinyl chloride (VCI) and vinylidene chloride (VCl₂) with acrylic acid (AA) and acrylyl chloride (ACI) were determined: VCI–AA, r₁ = 0.025, r₂ = 6.40; VCl–ACl, r₁ = 0.017, r₂ = 2.65; VCl₂–AA, r₁ = 0.46, r₂ = 1.26; VCl–ACl, r₁ = 0.50, r₂ = 1.12.     

Radical copolymerization of 2-ethylacrylic acid and methacrylic acid

Copolymers of 2-ethylacrylic acid (EAA) and methacrylic acid (MAA) were prepared in bulk and in N,N-dimethylformamide (DMF). Although precipitation of the copolymers was observed in bulk, the reaction mixtures remained apparently homogeneous in DMF. Best-fit terminal-model reactivity ratios were determined by a nonlinear least squares technique to be r_MAA = 1.14 and r_EAA = 0.23 in bulk, and r_MAA = 1.91 and r_EAA = 0.09 in 50% DMF solution. Examination of ¹³C-NMR spectra provided convincing evidence for the formation of statistical copolymers. Copolymerizations richer in MAA provided copolymers of higher molecular weights.     

Thermal stability of poly(vinyl bromide) and vinyl bromide-methyl acrylate copolymers. I

The thermal stability of PVB and five VB-MA copolymers with different compositions was studied by thermogravimetric analysis in dynamic nitrogen. The reactivity ratios of the copolymers were determined by using NMR techniques. It was found that r₁(VB) = 0.5 ± 0.1 and r₂(MA) = 7.3 ± 0.3. The stability of VB increases as the MA concentration in the copolymer compositions increases. Apparently, the formation of lactone and anhydride structures has a stabilizing effect. The stability imparted to the degrading copolymers by lactone and anhydride structures is insufficient to produce stability comparable to that of PMA itself.     

Esterolytic activity of imidazole-containing polymers. Synthesis and characterization of copoly[1-alkyl-4- or 5-vinylimidazole/4(5)-vinylimidazole] and its catalytic activity in the hydrolysis of p-nitrophenyl acetate

The water-soluble monomers, 1-methyl-4-vinylimidazole, 1-methyl-5-vinylimidazole, 1-ethyl-5-vinylimidazole, and 1-propyl-5-vinylimidazole have been synthesized, polymerized, and copolymerized with 4(5)-vinylimidazole. The copolymers were characterized by ¹⁴C-labeling, NMR, pK_a determination and viscosity measurements. The monomer reactivity ratios determined by ¹⁴C counting are r₁ = 1.04; r₂ = 0.94 [M₁ = 4(5)-vinylimidazole, M₂ = 1-methyl-4-vinylimidazole] and r₁ = 1.01; r₂ = 0.86 [M₁ = 4(5)-vinylimidazole, M₂ = 1-methyl-5-vinylimidazole]. The esterolytic activity of the copolymers for the hydrolysis of p-nitrophenyl acetate (PNPA) at pH 7–8 in 28.5% ethanol–water was higher than that of the mixtures of homopolymers. At pH 5–6 the esterolytic activities of the copolymers and the mixtures were similar. The most efficient esterolytic activity for PNPA hydrolysis at pH 7.11 in 28.5% ethanol–water occurred for copolymers containing 75 mole % 4(5)-vinylimidazole and for copolymers containing 1-methyl-4-vinylimidazole rather than 1-methyl-5-vinylimidazole.     

Acrylonitrile–4-vinylpyridine copolymers effect of comonomer sequence distribution on properties

Acrylonitrile–,4-vinylpyridine copolymers were prepared in chloroform solution at 60°C with AIBN as initiator. Copolymer compositions were determined from their 15.01-MHz ¹³C-NMR spectra. Reactivity ratios of r_AN = 0.093 and r_4VP = 0.32 were calculated by the Kelen and Tudos method. The run number, number-average sequence lengths, and monomer sequence distributions were also calculated. The T_g values of the copolymers, their dye uptake, and degree of alkaline hydrolysis were influenced by the overall copolymer composition but particularly by the monomer sequence distribution in the copolymers.     

Copolymerizations of alkyl methacrylates with vinyltriacetoxysilane

Copolymerizations of methyl methacrylate (MMA) and butyl methacrylate (BMA) with vinyltriacetoxysilane (VTAS) have been carried out in bulk at 70°. The compositions of the copolymers were determined from their silicon contents; the reactivity ratios were calculated by the Kelen-Tüdős method. For MMA/VTAS, r₁ = 7.75 ± 0.31 and for BMA/VTAS, r₁ = 4.62 ± 0.15; in both systems, r₂ is zero, indicating that VTAS does not homopolymerize under the experimental conditions. The influence of the silicon comonomer on properties of the copolymers, such as solubility annd thermal behaviour, was studied.     

Intramolecular excimer formation in macromolecules. I. Energy migration and excimer formation in copolymers exhibiting nearest-neighbor excimer interactions

Energy migration and intramolecular excimer formation have been studied in a series of copolymers comprising 1-vinylnaphthalene, 2-vinylnaphthalene, and styrene with methyl methacrylate. The technique of fluorescence depolarization was used to characterize energy migration in glassy solutions of the copolymers. The extent of energy migration in these copolymers is determined by the mean sequence length of aromatic species l?_a. Assuming that excimer formation occurs as a result of nearest-neighbor interactions, the concentration of excimer sites in the macromolecule will be proportional to the fraction of links between aromatic species f_aa. It is proposed that these sites are populated via energy migration from the site of absorption. Proportionality between the ratio of excimer to monomer emission intensities and the function l?_a·f_aa was predicted. Good agreement with this relationship was obtained in each of the copolymer systems studied. Reactivity ratios of methyl methacrylate (r_m) in copolymerization at 70°C with the aromatic monomers (r_a) were determined as: 1-vinylnaphthalene—r_m = 0.43, r_a = 1.71: 2-vinylnaphthalene—r_m = 0.37, r_a = 4.46; styrene-r_m = 0.45, r_a = 0.58.     

Copolymerization of optically active N-bornylmaleimide with vinyl monomers

Optically active N-bornylmaleimide (NBMI) was copolymerized with styrene, methyl methacrylate, and vinylidene chloride with a free-radical catalyst to obtain optically active copolymers. The monomer reactivity ratios for the radical copolymerization of NBMI (M₂) with styrene, methyl methacrylate, and vinylidene chloride were: ST-NBMI, r₁ = 0.13, r₂ = 0.05; MMA-NBMI, r₁ = 2.02, r₂ = 0.16; VCl₂-NBMI, r₁ = 1.15, r₂ = 0.47. The Q-e values for NBMI were Q₂ = 0.48 and e₂ = +1.47. The specific rotation and optical rotatory dispersion of these copolymers were measured. The correlation between the specific rotation and composition of these copolymers was not linear. The value of λ_c for each copolymer was independent of the copolymer composition and the comonomer, being 260 mμ for the St-NBMI system, 262 mμ for the MMA-system, and 260 mμ for the VCl₂-NBMI system. The effects of solvents and temperature on the specific rotation of these copolymers were investigated.     

The NMR Spectra of Styrene-Itaconate Ester Copolymers Obtained by Free Radical Mechanism

Styrene copolymerized with dimethyl itaconate and with methyl benzyl itaconate by use of a free radical initiator.

Monomer reactivity ratios for styrene (M₁)-dimethyl itaconate (M₂) co-polymerization were r₁ = 0.50 and r₂ = 0.06 and for styrene (M₁-methyl benzyl itaconate (M₂), r₁ = 0.42 and r₂ = 0.19. The nonconjugative methoxycarbonyl affected the monomer reactivity of itaconate toward polystyrene radical.

The NMR spectra of styrene-dimethyl itaconate copolymers were very complex and could not be interpreted because the two methoxy groups have similar chemical shifts.

The NMR spectra of styrene-itaconate copolymers were not so complex if methyl benzyl itaconate was used as comonomer instead of dimethyl itaconate. Methoxy and benzyloxy absorptions were sufficiently separated and “co-isotacticity” could be determined.

It is shown that the nonconjugative methoxycarbonyl group had little influence on the steric course of the cross-propagation reaction between styrene and itaconate.     

Self-crosslinkable polymers. I. Copolymerization of glycidyl methacrylate with 2-vinylpyridine and 2-vinyl-5-ethylpyridine

A soluble and self-crosslinkable linear copolymer with pendant epoxy and pyridyl groups was obtained from glycidyl methacrylate (M₁) and 2-vinylpyridine (M₂) or 2-vinyl-5-ethylpyridine (M₂) by the action of azobisisobutyronitrile. The monomer reactivity ratios were determined in tetrahydrofuran at 60°C: r₁ = 0.510, r₂ = 0.620 with 2-vinylpyridine and r₁ = 0.57, r₂ = 0.62 with 2-vinyl-5-ethylpyridine. These were consistent with the calculated values with the reported Q and e values for these monomers. The intrinsic viscosities of the copolymers with 2-vinylpyridine and with 2-vinyl-5-ethylpyridine were found to be 0.17–0.19 and 0.26–0.38, respectively, in tetrahydrofuran at 30°C; they were independent of the copolymer composition. The copolymers were amorphous, had no clear melting points, and became insoluble crosslinked polymers under heating without further addition of any curing agents.     

Thermal stability of poly(vinyl bromide) and copolymers of vinyl bromide with methyl vinyl ketone

Thermal stability and degradation behaviour have been studied for PVB and VB-MVK copolymers spanning the whole composition range, using thermogravimetric analysis. The reactivity ratios in the radial copolymerization were determined by using an NMR technique, leading to r_i(VB) = 3.6 ± 0.2 and r₂(MVK) = 0.2 ± 0.1. The introduction of MVK units into the VB chain leads to an interaction with release of methyl bromide. The stability of the copolymers increases with increasing MVK concentration.     

Copolymerization of Acrylonitrile with Functional Silanes

Acrylonitrile (AN) has been copolymerized with vinyltriethoxy-silane (VTES) and vinyltris(methoxy ethoxy)silane (VTMES) in bulk at 60°C using benzoyl peroxide. The copolymer composition has been determined from elemental analysis. The reactivity ratios of AN (MI) copolymerizations with VTES (r₁ = 4.72, r₂ = 0) and VTMES (r₁ = 2.45, r₂ = 0) have been determined. Mechanistic explanations of the monomer reactivities are presented. The structure-property relationship of AN-vinylsilane copolymers has been discussed.     

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.     

丙烯酸甲酯与N-对卤苯基甲基丙烯酰胺共聚合的研究

<正> 我们已经报道过甲基丙烯酸甲酯与N-对卤苯基甲基丙烯酰胺共聚合的研究。本文工作合成了丙烯酸甲酯与N-对卤苯基甲基丙烯酰胺共聚体,研究了这二组共聚体系的聚合反应、共聚体的组成、估算了单体的竞聚率,比较了这两种酰胺对丙烯酸甲酯与甲基丙烯酸甲酯的反应活性。     

Determination of the sequence distribution and stereoregularity of ethyl α-benzoyloxymethylacrylate–methyl methacrylate copolymers by means of proton and carbon-13 NMR

Proton and Carbon-13 NMR spectra of ethyl α-benzoyloxymethylacrylate (E)–methyl methacrylate (M) copolymers were analyzed in terms of sequence distribution and stereoregularity of monomer units. The copolymers were prepared by free radical polymerization in benzene at 50°C. The methoxy region of the M proton signal resonance was found to be sensitive to the copolymer composition for M-centred sequences. The carbon-13 NMR spectra of the EM copolymers, in particular the carbonyl signal resonances of carbomethoxy and carboethoxy groups, are discussed in terms of M- and E-centred configurational sequences. The experimental values were in excellent agreement with those calculated taken into account the terminal copolymerization model and Bernoullian distribution of stereoregularity with the statistical parameters determined from reactivity ratios r_E = 0.32 and r_M = 1.34 and the coisotacticity parameters σ_MM = 0.22, σ_EE = 0.70, and σ_ME = σ_EM = σ = 0.30. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3483–3493, 1997     

Organometallic and enzymatic catalysis for ring opening copolymerization of ε‐caprolactone and 4‐methyl‐ε‐caprolactone

A series of copolymers containing ε‐caprolactone (CL) and 4‐methyl‐ε‐caprolactone (MeCL) were synthesized by ring‐opening polymerization (ROP) using Tin(II) bis(2‐ethylhexanoate)(Sn(Oct)₂) or Novozym 435 as catalyst. The molecular structure and weight of copolymers were determined by nuclear magnetic resonance (NMR) and size exclusion chromatography (SEC), respectively. Our kinetic study showed that the monomer reactivity ratios for CL (r₁) and MeCL (r₂) using Sn(Oct)₂ as catalyst were estimated to be near unity and r₁ × r₂ = 1, indicating the random distribution of the monomers in the final copolymer. The results of DSC and XRD consistently indicated that the copolymers were inclined to be amorphous with the increasing of MeCL fraction. Microspheres were prepared from copolymers and characterized by SEM. The preliminary degradability and biocompatibility studies on these copolymers were also assessed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011