Copolymerization of acrylonitrile. III. Copolymerization with α-cyanocinnamamide

Acrylonitrile was copolymerized in solution with α-cyanocinnamamide up to low conversions. The conventional scheme of copolymerization fitted this copolymer. The basic properties, such as solubility, viscosity, and thermal behavior, of the copolymer prepared in bulk and in solution were determined.     

Terpolymerization studies. III. Terpolymerization of acrylonitrile,styrene, and α-cyanocinnamamide

Acrylonitrile (M₁), styrene (M₂), and α-cyanocinnamamide (α-CCA) (M₃) were terpolymerized by thermal initiation to low conversion, and the monomer feed/terpolymer composition relationship was determined by Slocombe's triangular graph. The solubility, the thermal behavior, the impact strength, and the chemical resistance of the terpolymers of various compositions were investigated.     

Copolymerization of studies. Copolymerization of methyl α-cyanocrotonate with styrene,acrylonitrile, and vinyl acetate

Copolymers of methyl α-cyanocrotonate with styrene, acrylonitrile, and vinyl acetate were prepared in bulk by free radical initiation. The copolymerization parameters were determined for each pair by several methods. The basic properties, that is, intrinsic viscosity, solubility, melting range, and glass transition temperature of the obtained copolymers, were determined.     

Copolymerization of β-pinene with styrene oxide and N-vinylpyrrolidone

The copolymerization of β-pinene with styrene oxide (SO) and β-pinene with N-vinylpyrrolidone (VP) was investigated by using SnCl₄ in dichloromethane diluent at low temperature. Monomer reactivity ratios were evaluated for both copolymers at ?80°C; these are r₁(SO) = 2.979 and r₂(β-pinene) = 0.002 and r₁(VP) = 0.096 and r₂(β-pinene) = 0.294.     

Copolymerization with depropagation. V. Copolymerization of α-methylstyrene and methyl methacrylate between their ceiling temperatures

The variation of copolymer composition with monomer feed has been studied for the system α-methylstyrene-methyl methacrylate at 60, 114 and 147°C. The compositions predicted by the diad model of Part III of this series accurately describe the data.     

H NMR titration and quantum calculation for the inclusion complexes of styrene and α-methyl styrene with α, β and γ-cyclodextrins

The inclusion behavior between styrene (α-methyl styrene) and cyclodextrins (CDs) was studied by using ¹H NMR titration in solution. The results indicate that 1:1 inclusion complexes were formed. The association constants of the inclusion complexes were determined by nonlinear least-square method. The inclusion process was also studied by using PM3 quantum-mechanical semi-empirical method. The calculated results are in agreed with the experimental data.     

Copolymerization of vinyl acetate with ethyl α-cyanocinnamate

Trisubstituted ethylene, ethyl α-cyanocinnamate, is readily copolymerized with vinyl acetate by a conventional radical initiator. Terminal, penultimate, and “complex” copolymerization models were applied by using the data of composition of the copolymers obtained in bulk and by copolymerization in benzene, ethyl acetate, and chloroform. The model based on the participation of the monomer complexes describes satisfactorily the deviation from the terminal copolymerization model. The proton NMR analyses of the monomer mixtures indicate that the interaction between the monomers leads to the formation of weak monomer complexes. Kinetic studies of the initial rate dependence on the total monomer concentration and monomer feed composition enabled us to evaluate the degree of participation of the free uncomplexed monomers and the monomer complex in the propagation reactions. The contribution of the complexed monomers in the propagation stages increases with the increase in total monomer concentration. The initial rate of the copolymerization is proportional to the square root of the initiator concentration, thus confirming the bimolecular termination of the macrochains. The rate constants of the addition reactions of the complex and free monomers were evaluated from the kinetic studies. The quantitative kinetic treatment provided information regarding the relative weight of the termination reaction and indicated that the termination in the system occurs predominantly by the cross-termination reaction between two growing polymer radicals with different kinds of monomer units at the ends. Additional information on the termination in this system was obtained from viscosity measurements.     

Functional polymers. XLIX. Copolymerization of ω-alkenoates with α-olefins and ethylene

The 2,6-dimethylphenyl ester of 10-undecenoic acid was copolymerized with 1-dodecene, 1-octene, 1-hexene, propylene, and ethylene using coordination initiation systems based on “aluminum-activated” titanium trichloride and dialkylaluminum chlorides. The copolymerizations with higher α-olefins proceeded smoothly and gave copolymers incorporating from 60 to 90% of the 10-undecenoate feed. Copolymerization with propylene gave incorporation of 5 mol % of 2,6-dimethylphenyl 10-undecenoate; with ethylene only 3 mol % of the ω-alkenoate was readily incorporated. All copolymers were characterized by elemental analysis, dilute solution viscosity, and by their IR ¹H- and ¹³C-NMR spectra.     

Cationic polymerization of β-pinene,styrene and α-methylstyrene

Molecular weight distributions determined by gel permeation chromatography demonstrate that α-methylstyrene copolymerizes with both β-pinene and styrene, forming both bi- and terpolymers. The composition of precipitated polymer versus crude polymer, as determined by nuclear magnetic resonance, suggests that β-pinene and styrene also copolymerize. Extraction of the latter bipolymer of β-pinene and styrene with acetone gives only a small amount of insoluble β-pinene homopolymer, confirming that β-pinene and styrene copolymerize in m-xylene. GPC analysis shows that each copolymer contains some homopolymer. A comparison of M _n with molecular weight calculated from NMR analysis, assuming chain transfer to solvent, indicates that chain transfer is the predominant method of forming dead polymer. The carbonium ions of the growing chain tend to transfer to solvent with increasing ease in the order β-pinene, styrene, and α-methylstyrene.     

γ Radiolysis of polyethylene grafted with styrene

γ Radiolysis of polyethylene grafted with styrene of 0–76 wt % was carried out at 30–100°C in vacuo with a dose rate of 6.35 × 10⁵ rad/hr. The formation of hydrogen and trans-vinylene unsaturation decreased as the content of styrene unit in polymer increased and the rate of formation was described by zero-order formation kinetics with respect to each concentration combined with first-order disappearance. The gel fraction changed with the content of styrene unit according to irradiation time and temperature. The gel data were evaluated by using the Charlesby–Pinner equation. Kinetic analysis showed that in γ radiolysis of polyethylene grafted with styrene the formation of hydrogen is somewhat retarded, the crosslinking and main chain scission are accelerated, and the disappearance of hydrogen and formation and disappearance of trans-vinylene unsaturation are almost entirely unaffected. On the basis of these results the reactions induced by γ rays in graft polymer were discussed in connection with the reaction mechanisms of the γ radiolyses of polyethylene and polystyrene.     

Kinetics of the reactions of cyclopropane derivatives. V. The gas-phase unimolecular reactions of 1 α-chloro-2α,3α-dimethylcyclopropane and 1α-chloro-2α,3β-dimethylcyclopropane

Thermolysis of the “all-cis” compound 1α-chloro-2α,3α-dimethylcyclopropane (A) at 550–607 K and 6–115 torr is a first-order homogeneous non-radical-chain process giving penta-1,3-diene (PD) and HCl as products. The Arrhenius parameters are log₁₀A(sec^?1) = 13.92 ± 0.08 and E = 199.6 ± 0.9 kJ/mol. The isomer with trans-methyl groups, 1α-chloro-2α,3β-dimethylcyclopropane (B) reacts by two parallel first-order processes giving as observed products trans-4-chloropent-2-ene (4CP) and PD + HCl, with log₁₀A(sec^?1) = 14.6 and 13.8, respectively, and E = 199.5 and 190.2 kJ/mol, respectively. The 4CP undergoes secondary decomposition to PD + HCl (as investigated previously). Comparison of the results for compounds (A) and (B) with those for other gas-phase and solution reactions leads to the conclusion that the gas-phase thermolyses proceed by rate-determining ring opening to form olefins which may decompose further by thermal or chemically activated reactions, and that the ring opening is a semiionic electrocyclic reaction in which alkyl groups in the 2,3-positions trans to the migrating chlorine semianion move apart, with appropriate consequences for the rate of reaction and the stereochemistry of the products.     

Isomerization of unsaturated radicals. V. Unimolecular isomerization of hot α,α- and α,β-dimethallyl radicals

The 147 nm photolysis of 3,3 dimethylbut-1-ene leads mainly to the formation of very hot (?375 kJ/mol) α,α-dimethallyl radicals. On the other hand, that of 3-methyl-cis-and trans-pentene-2, as well as that of 2,3-dimethylbut-1-ene is a source of very hot α,β-dimethallyl radicals. These allylic radicals are coolled down using pressure and are allowed to combine with available methyl radicals. From the formation of various C₆H₁₂ products, it is concluded that the very hot α,α- radical isomerizes towards the α,β-structure at low pressures and vice versa. The equilibrium constant of the following process has been evaluated to be 1.72 ± 0.30.      

Copolymerization of trioxane by γ-radiation

High molecular copolymers of trioxane with different cyclic ethers and formals were produced by γ-radiation from a ⁶⁰Co source. It was polymerized in the solid state at 53°C. Polymerization does not occur in the melt. Irradiation was carried out with exclusion of air at a dose rate of 7 × 10³ rad/hr. The polymerization rate was increased very considerably in the presence of 1,3-dioxolane and epichlorhydrin; the addition of other comonomers may reduce the yield. The concentration of the comonomer is generally higher in the polymer than in the initial mix. These comonomers which increase the polymerization rate are introduced preferentially into the polymer chain; this is proved by the unstable polymer part and the thermal stability. Experiments with the trioxane–1,3-dioxolane system revealed that the unstable polymer part is markedly reduced and the heat stability considerably inproved with rising concentrations of this monomer. The thermal stability and the reduced viscosity of these copolymers are within the range of technical processability.     

Copolymerization of β-butyrolactone and β-benzyl malolactone with aluminoxane catalysts

Poly (β-hydroxylbutyrate-co-benzyl β-malolactonate), (P-HB-co-BML) copolymers, were prepared by the ring-opening copolymerizations of β-butyrolactone (BL) and benzyl β-malolactone (BML) with several alkyl aluminoxane catalysts, including ethylaluminoxane (EAO), methylaluminoxane (MAO), and isobutylaluminoxane (IBAO). The copolymers had very broad molecular weight distributions with weight average molecular weights, M̄_w, greater than 200,000. The products were fractionated by solubility into acetone-soluble and insoluble copolymers. The former were random, atactic copolymers while the latter were stereoblock copolymers. Random, atactic copolyesters of these two monomers were also obtained with the diethylzinc-water, ZnEt₂-H₂O (0.6:1), and the (5,10,15,20-tetraphenylporphinato)aluminium chloride, TPPAlCl, catalysts. The copolymerization reactions with the latter two catalysts gave much higher yields (up to 98%) and better control of both the copolymer compositions and the molecular weight distributions, but these copolymers had M̄_w values of only 20,000 or less. The copolymer tacticities and comonomer sequences were determined by ¹³C NMR spectroscopy.     

Radical copolymerization of acrylic monomers. VIII. Copolymerization of methyl methacrylate with methyl α-p-chlorobenzylacrylate and methyl methacrylate with methyl α-p-methoxybenzylacrylate

Free-radical copolymerization of methyl methacrylate with methyl α-p-chlorobenzylacrylate and methyl methacrylate with methyl α-p-methoxybenzylacrylate have been studied in benzene solution at 40°C. Although a simple copolymerization model fits the composition data, the kinetic behavior of both copolymerization systems are analyzed from simple and reversible copolymerization models, taking into account the relatively low ceiling temperature of both methyl α-(p-substituted benzyl)acrylates and considering that the overall rate of copolymerization drastically decreases with the increase of the corresponding methyl α-(p-substituted benzyl)acrylate molar fraction in the feed.     

Thermal deesterification and decarboxylation of alternating copolymers of styrene with β-substituted t-butyl α-cyanoacrylates

Alternating copolymers of styrene with β-carboalkoxy-substituted t-butyl α-cyanoacrylates undergo facile deesterification at 150–190°C, about 60°C below the deprotection temperature of poly(t-butyl methacrylate), and decarboxylation at 170–200°C. When the β-substituent is a methyl ester, the two events are clearly separated, with the deesterification occurring at a maximum rate at 165°C and decarboxylation at 193°C. Anhydride formation is negligible in this case. The copolymer with t-butyl cyanofumarate exhibits simultaneous deesterification and decarboxylation events at 180°C with concomitant minor dehydration.