Dispersion copolymerization of styrene and other vinyl monomers in polar solvents

Dispersion polymerization is a very attractive method for preparing micrometer‐size monodisperse polymer particles. The applications of microspheres have been greatly expanded by the use of copolymers. Here, the dispersion copolymerization of styrene and seven other vinyl monomers was carried out in polar solvents. The effect of the different comonomers on the particle size was systematically investigated. The particle size first decreased and then increased with an increasing fraction of acrylamide in the monomer feed, and at a higher fraction of such a comonomer, only a gel‐like polymer was obtained. The particle size also increased with the increase in the contents of the hydrophilic comonomers in the monomer mixtures, and the copolymer molecular weight decreased meanwhile. Although the amount of the hydrophobic comonomer in the monomer mixture changed, the particle size was hardly affected. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 555–561, 2001     

A versatile method for cyclic polymers from conjugated and unconjugated vinyl monomers

A versatile method was introduced to prepare cyclic polymers from both conjugated and unconjugated vinyl monomers. It was developed on the combination of the RAFT polymerization and the self‐accelerating double strain‐promoted azide‐alkyne click (DSPAAC) reaction. In this approach, a switchable chain transfer agent 1 was designed to have hydroxyl terminals and a functional pyridinyl group. The protonation and deprotonation of pyridinyl group endowed the chain transfer agent 1 with a switchable control capability to RAFT polymerization of both conjugated and unconjugated vinyl monomers. Based on this, RAFT polymerization and the following hydroxyl end group modification were used to prepare various azide‐terminated linear polymers including polystyrene, poly(N‐vinylcarbazole), and polystyrene‐block‐poly(N‐vinylcarbazole). Using sym‐dibenzo‐1,5‐cyclooctadiene‐3,7‐diyne (DBA) as small linkers, the corresponding cyclic polymers were then prepared via the DSPAAC reaction between DBA and azide terminals of the linear precursors. Due to the self‐accelerating property of DSPAAC reaction, this bimolecular ring‐closing reaction could efficiently produce the pure cyclic polymers using excess molar amounts of DBA to linear polymer precursors. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1811–1820     

Coordination-insertion copolymerization of allyl monomers with ethylene

Coordination-insertion copolymerization of allyl monomers with ethylene was developed by using a palladium/phosphine-sulfonate catalyst. A variety of allyl monomers, including allyl acetate, allyl alcohol, protected allylamines, and allyl halides, were copolymerized with ethylene to form highly linear copolymers that possess in-chain -CH(2)CH(CH(2)FG)- units.     

Photodegradation in solution of copolymers of methyl vinyl ketone and methyl isopropenyl ketone with methyl methacrylate

Copolymers of methyl vinyl ketone (MVK) and methyl isopropenyl ketone (MIK) with methyl methacrylate (MMA), have been prepared covering the whole composition range. Reactivity ratios have been estimated as follows: MMA/MVK, r_MMA = 0·63 ± 0·2, r_MVK = 0·53 ± 0·2; MMA/MIK, r_MMA = 0·98 ± 0·2, r_MIK = 0·69 ± 0·2. Number average molecular weights have been measured during the course of photodegradation under 253·7 nm radiation in methyl acetate solution and rates of chain scission calculated. In each system the copolymers are less stable than the corresponding homopolymers, the rate passing through a maximum at 20–30% ketone content. These results have been discussed from a mechanistic point of view.     

Radical copolymerization of cyclic diarsine with vinyl monomers

1,2,4,5‐Tetramethyltetrahydrodiarsenine ( 1 ), a cyclic diarsine compound, was stirred with styrene and a catalytic amount of 2,2′‐azobisisobutyronitrile (AIBN) as a radical initiator at 80 °C for 8 h in toluene to give a copolymer containing arsenic atoms in the backbone. The gel permeation chromatography (GPC) chromatogram of the copolymer showed a single peak. The number‐average molecular weight of the copolymer was estimated to be more than 10,000 by GPC analysis (CHCl₃, polystyrene standards). The structure of the copolymer was confirmed by the ¹H NMR and ¹³C NMR spectra. According to the integral ratio of peaks in the ¹H‐NMR spectrum, the content of 1 in the copolymer was smaller compared to the monomer feed ratio of 1 . Radical copolymerization of 1 with methyl methacrylate also provided the corresponding copolymer in the presence of AIBN, whereas copolymerization with vinyl acetate yielded no polymeric material. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3023–3028, 2004     

Hybrid copolymerization of cyclic and vinyl monomers

In this work,we report the hybrid copolymerization of various cyclic monomers and vinyl monomers.Our studies demonstrate that 1-tert-butyl-4,4,4-tris-(dimethylamino)-2,2-bis[tris(dimethylamino) phophoranyliden-amino]-2 5,5-catenadi(phosphazene) (t-BuP 4) can catalyze the hybrid copolymerization of caprolactone (CL),lactide (LA) or cyclic carbonate ester with acrylate or methyl acrylate.However,the polymerization of cyclosiloxane with vinyl monomers yields two corresponding homopolymers,and the polymerization of lactone with acrylonitrile (AN) produces only polyacrylonitrile.Clearly,the extent of matching of activity between a monomer and an active center determines whether or not there is hybrid copolymerization.     

Electroinduced oxidative copolymerization of N‐vinyl carbazole with methyl ethyl ketone formaldehyde resin

In this study, a novel procedure to obtain the non‐crosslinked, photoconductive, white form of the linear copolymer of N‐vinyl carbazole (NVCz) and methyl ethyl ketone formaldehyde resin (MEKF‐R) is reported. A possible mechanism of copolymerization is suggested. The yield of the copolymer is increased almost 10 times by the addition of catalytic amounts of ceric ammonium nitrate as an oxidant during the electrochemical polymerization of NVCz in the presence of MEKF‐R in a divided electrochemical cell. Since cerium(III) is readily oxidized to cerium(IV) at the anode, the concentration of cerium(IV) remained constant and the deposition of green poly(NVCz) can be prevented. Copyright © 2004 John Wiley & Sons, Ltd.     

60Co-initiated copolymerization of styrene with vinyl acetate

The kinetic behavior of the ⁶⁰Co-initiated copolymerization at 25°C of styrene with vinyl acetate at 1100 and 2000 rad/hr was studied. As in the case of thermal and photochemical copolymerizations of these monomers, the growing chains are particularly rich in styrene units, and the overall rate is affected by a diluent effect due to the vinyl acetate monomer. However, in the case of the radiation copolymerization, this effect is partially counterbalanced by an increase of the initiation rate with the vinyl acetate concentration; the polymerization rate curve shows a maximum at a vinyl acetate molar fraction of 0.25. This effect is due to the very different free radical yields of these two monomers. The experimental results may be understood on the basis of a kinetic scheme which involves an energy transfer process from the excited vinyl acetate molecules to the styrene monomer and a termination reaction of the growing chains by very short styrene radicals when the mixture is rich in vinyl acetate.     

Copolymerization of methyl vinyl ketone with styrene in the presence of cobalt(II) nitrate

Copolymerization of methyl vinyl ketone (MVK) with styrene was carried out at 50°C in the presence of cobalt(II) nitrate. The resulting monomer reactivity ratios decreased with an increasing concentration of the cobalt salt. This finding suggests that the metal salt participates in the propagation step of the copolymerization. Absolute copolymerization parameters were determined by assuming a three-component system as free MVK (M₁), MVK complexed with cobalt(II) nitrate (M₂), and styrene (M₃): k₁₁/k₁₂ = 0.184, k₁₁/k₁₃ = 0.235, k₂₂/k₂₁ = 7.18 × 10⁻², k₂₂/k₂₃ = 6.79 × 10⁻⁴, k₃₃/k₃₁ = 0.380, and k₃₃/k₃₂ = 2.77 × 10⁻³, and Q₂ = 19.65 and e₂ = 2.83. The complexed MVK monomer is more reactive to the polymer radical with the terminal styrene unit than the free MVK. Very small values for the monomer reactivity ratios, k₂₂/k₂₃ and k₃₃/k₃₂, show the marked alternating tendency for the copolymerization of the complexed monomer with styrene. In practice, however, alternating copolymer could not be obtained because of the poor solubility of cobalt(II) nitrate.     

Extent of complex participation in the rate of copolymerization of styrene with maleic anhydride in methyl ethyl ketone

Georgiev and Shirota's simplified terminal complex model was applied to the dilatometrically measured initial rate of copolymerization of sytrene (ST) with maleic anhydride (MA) in methyl ethyl ketone (MEK) at 50°C. The rate was maximum at the feed MA mole fractions of 0.752, 0.769, and 0.806 at the total monomer concentrations of 2M, 1.5M, and 0.5M, respectively. Shirota's method gave the following ratios of propagation rate constants: β_A=k_AC/k_AD = 8.25 and β_D = k_DC/k_DA = 2.70. Georgiev's method gave β_A = 14, β_D = 2.7, and α = k_AD/k_DA = 22. The equilibrium constant of the donor-acceptor complexation between ST and MA in MEK was measured to be 0.045 dm³/mol at room temperature.     

Radical copolymerization of 3-tri-n-butylstannylstyrene with several vinyl monomers

The free radical homopolymerization and copolymerization of 3-tri-n-butylstannylstyrene (3-BTS) with styrene (ST), ethyl acrylate (EA), methyl methacrylate (MMA), vinyl acetate (VA), and acrylonitrile (AN) were carried out using 2,2′-azobisisobutyronitrile (AIBN) at 60°C. It was found that the yield of conversion to poly(3-BTS) increased with the molar ratio of initiator to monomer as well as with polymerization time. The conversion at equilibrium after 50 h was about 40%. The compositions of copolymer samples were determined from elemental analyses. Monomer reactivity ratio and Q-e values were calculated. The copolymers of 3-BTS-MMA and 3-BTS-AN were found to be alternating. The copolymers of 3-BTS with MMA, EA and AN were not soluble in any of a large number of organic solvents tested. The insolubility is believed to be due to formation of intermolecular coordination among the tributylstannyl moiety and the carbonyl or cyano groups of the polymer. These copolymers, however, were “soluble” in trihaloacetic acid, but this solubility was due to a cleavage of the trialkyltin moiety from the phenyl groups. The glass temperatures, T_g, and melting temperatures T_m, of the various polymers were also studied.     

Spontaneous copolymerization of 1,3-cyclohexadiene with polar vinyl monomers

In the reactions of 1,3-cyclohexadiene(1,3-CHD) with polar vinyl monomers, CH₂?C(X)Y (X is -? CN and ? CO₂CH₃; Y is ? CI, ? H, and ? CH₃), the two α-chlorosubstituted monomers underwent rapid spontaneous copolymerization, accompanied by the formation of a small amount of cycloadduct. Both polar monomers also gave predominantly copolymers in the reaction with 1,3-cycloheptadiene(1,3-CHpD) in lower yield. 1,3-Cyclooctadiene (1,3-COD) reacted only with α-chloroacrylonitrile (CAN) to give a copolymer, while only cycloaddition took place in systems involving cyclopentadiene(CPD) as diene. The charge–transfer (CT) complex formation of 1,3-CHD with CAN and methyl α-chloroacrylate(MCA) was confirmed by ultraviolet spectroscopic studies and the equilibrium constants estimated were 0.18 and 0.07 liter/mole, respectively, at 25°C in chloroform as solvent. The activation energies for the copolymerizations of 1,3-CHD with CAN and MCA in benzene were determined to be ca. 6.6 and 9.6 kcal/mole, respectively. In the system composed of 1,3-CHD and CAN, only the copolymerization was affected by solvents used and oxygen. Although addition of ZnCl₂ to the system resulted in the acceleration of the both reactions, the variation in the product ratio of copolymer to cycloadduct with ZnCl₂ concentration showed a maximum. Based on the results in the present and preceding studies for systems involving 1,3-cyclodienes and acceptor monomers, the relationship between the cycloaddition and the spontaneous copolymerization is discussed.     

Anionic graft copolymerization of diene polymers with vinyl monomers

A mixture of homopolymer and graft copolymer was obtained by adding the monomer at 0°C to the polylithiodiene solution. Styrene, methyl methacrylate, and acrylonitrile were used as the monomers. Polylithiodienes were prepared by the metalation of diene polymers, i.e., polybutadiene or polyisoprene, with the use of n-butyllithium in the presence of a tertiary amine (N,N,N′,N′-tetramethylethylenediamine) in n-heptane. The graft copolymers were separated by solvent extraction and were confirmed by turbidimetric titration and elementary analysis. Oxidation of the polybutadiene–styrene grafts revealed that the molecular weight of the side chains was the same as the molecular weight of the free polystyrene formed. The grafting efficiency and grafting percentage were studied for polybutadiene–styrene graft copolymers prepared under various conditions.     

Radiation-induced copolymerization of methyl trifluoroacrylate with ethylene

Copolymerization of methyl trifluoroacrylate (MTFA) with ethylene in bulk was induced by γ irradiation. The copolymerization was observed to proceed in the liquid monomer mixture of MTFA and ethylene at 25°C with the dose rates ranging from 5.0 × 10⁴ to 1.0 × 10⁶ rad/hr. A wide range of the initial monomer composition gives an almost equimolar and alternating copolymer. The highest polymerization rate was observed at the equimolar monomer composition. The dose rate exponent of the polymerization rate is unity. The reactivity ratios of r₁ (MTFA) and r₂ (ethylene) were determined to be 0.034 and 0.14, respectively.     

Radiation induced copolymerization reactivity of different allyl monomers with styrene

Radiation induced copolymerizations of electron donating such as allyl phenol (AP) and electron withdrawing such as allyl isothiocyanate (AITC) monomers with styrene (Sty) as a comonomer were studied in order to correlate the electronic behavior with copolymerization yield and molecular weight. The allyl monomers and comonomer were mixed in the same mol ratios under Ar atmosphere and copolymerized by using gamma radiation in various absorbed doses (55, 110, 165 kGy) obtained from a Co-60 source. Poly(AP-co-Sty), and poly(AITC-co-Sty) could have been prepared at all of the absorbed doses. The maximum copolymerization yields were calculated as a 16.35 and 6.52 percent for poly(AP-co-Sty) and poly(AITC-co-Sty), respectively. The molecular weights of poly(AP-co-Sty) copolymers are found to be higher in comparison to those of poly(AITC-co-Sty). Both results indicate that, under the same irradiation conditions, AP is more reactive on styrene than AITC is. Thus, the monomers having electron withdrawing (EW) substituents attached to allyl group may result in better copolymerization yield and molecular weight than those with electron donating (ED) substituents. Thermal stabilities of the poly(AP-co-Sty) copolymers are also higher than those of poly(AITC-co-Sty).     

Polymerization of coordinated monomers. XVII. Alternating copolymerization of methyl methacrylate with styrene by boron compounds

By the use of various boron compounds methyl methacrylate and styrene were copolymerized under photoirradiations at ?20°C. The alternately regulating activities of the boron compounds in the copolymerizations were in the following order: boron trichloride > ethylboron dichloride > boron trifluoride > diethylboron chloride ? triethylboron (?0). Boron trichloride and ethylboron dichloride exhibited such high regulating activities that their presence in 1 mol% in the charged methyl methacrylate was sufficient to complete equimolar alternating copolymerization. The alternating copolymerization proceeded in the steady state. The copolymerization rates decreased in the following order: boron trichloride ? ethylboron dichloride > diethylboron chloride ? triethylboron (?0). The cotacticities of methyl methacrylate-centered triads in the resulting copolymers were identical to those prepared with boron trichloride, ethylboron dichloride, and diethylboron chloride. The mechanism of the alternating copolymerization is discussed.     

Aza-Baylis-Hillman reaction of salicyl N-tosylimines with methyl vinyl ketone, ethyl vinyl ketone or phenyl vinyl ketone

Reactions of salicyl N-tosylimines with methyl vinyl ketone, ethyl vinyl ketone or phenyl vinyl ketone proceeded smoothly under mild conditions to give the corresponding chromanes or aza-Baylis-Hillman adducts in moderate to excellent yields in the presence of phosphine or nitrogen Lewis base.     

Emulsion copolymerization of styrene and methyl methacrylate

Chain transfer constants to monomer have been measured by an emulsion copolymerization technique at 44°C. The monomer transfer constant (ratio of transfer to propagation rate constants) is 1.9 × 10^?5 for styrene polymerization and 0.4 × 10^?5 for the methyl methacrylate reaction. Cross-transfer reactions are important in this system; the sum of the cross-transfer constants is 5.8 × 10^?5. Reactivity ratios measured in emulsion were r₁ (styrene) = 0.44, r₂ = 0.46. Those in bulk polymerizations were r₁ = 0.45, r₂ = 0.48. These sets of values are not significantly different. Monomer feed compcsition in the polymerizing particles is the same as in the monomer droplets in emulsion copolymerization, despite the higher water solubility of methyl methacrylate. The equilibrium monomer concentration in the particles in interval-2 emulsion polymerization was constant and independent of monomer feed composition for feeds containing 0.25–1.0 mole fraction styrene. Radical concentration is estimated to go through a minimum with increasing methyl methacrylate content in the feed. Rates of copolymerization can be calculated a priori when the concentrations of monomers in the polymer particles are known.