Ionic graft copolymerization. V. Graft copolymerization of β-propiolactone onto the trunk polymers containing carboxylic acid,sulfonic acid,and other salts

β-Propiolactone (βPL) was graft-copolymerized onto styrene–divinylbenzene copolymers containing various carboxylates or sulfonates, composed of anions and cations having different electronegativities. In parallel, the mechanism of polymerizations of βPL by relatively neutral catalysts was studied in comparison with the behaviors of graft copolymerizations. In the graft copolymerization onto the trunk polymer containing various carboxylates, a lower electronegativity of countercation favors a higher anionic polymerization activity and the order of rate of polymerization coincides with that of anionic activities of catalysts. On the other hand, in the case of trunk polymer containing sulfonates, a higher electronegativity of countercation favors a cationic polymerization activity, and the order of rate of polymerization coincides with that of cationic activity of catalyst. The order of grafting efficiency at fixed total conversion coincides almost with that of anionic activity. The comparatively higher grafting efficiency in the grafting onto trunk polymer containing carboxylic acid might support an anionic graft copolymerization mechanism by carboxyl anion. The two following mechanisms were proposed for the initiation of the polymerization by the trunk polymer containing sodium sulfonate, in which acrylic acid is transformed from βPL.     

Ionic graft copolymerization. III. Graft copolymerization of β-propiolactone onto polyacrylonitrile containing diketene units

Polyacrylonitrile (PAN)–β-propiolactone (βPL) graft copolymer was synthesized by means of the ionic polymerization of βPL in the presence of polyacrylonitrile containing diketene units by using basic catalysts. A graft copolymer was produced by the copolymerization of βPL with the lactone ring in the trunk polymer. In this graft copolymerization method, the grafting efficiency was low. However, grafting efficiency increased with the mole ratio of polymeric lactone to βPL; also higher molecular weight of PβPL favored higher grafting efficiency. The reactivity ratio of polymeric lactone to βPL was estimated to be in the range of 0.1–0.3.     

Ionic graft copolymerization. VII. Ionic graft copolymerization of β-propiolactone onto the trunk polymers containing pyridine,amide, sulfonyl chloride,and carboxylic acid anhydride groups

The graft copolymerization of β-propiolactone (βPL) onto the various trunk polymers containing polar substituents such as pyridine, amide, sulfonyl chloride, and carboxylic acid anhydride groups was carried out. In the grafting onto the basic trunk polymer containing 4-vinylpyriding units, two kinds of grafting mechanism are supposed. In the case of rigorously dried trunk polymer, the polymerization is initiated by betaine and proceeds with higher grafting efficiency. Another is initiated by pyridinium hydroxide and proceeds with lower grafting efficiency. Another is initiated by pyridinium hydroxide and proceeds with lower grafting efficiency in the presence of some amount of water. With acidic trunk polymer containing sulfonyl chloride groups, no graft copolymer was produced. The grafting efficiency of βPL onto the amphoteric trunk polymer containing acrylamide units was found to be between those of basic and acidic trunk polymer. In addition, the grafting by means of ionic copolymerization of βPL with maleic anhydride units contained in trunk polymer proceeded with very high grafting efficiency.     

Ionic graft copolymerization. II. Graft copolymerization of β-propiolactone onto acrylonitrile–sodium acrylate copolymer

Polyacrylonitrile–β-propiolactone (βPL) graft copolymer was synthesized by means of ionic polymerization, in which polymerization of βPL was initiated by polyacrylonitrile containing a small amount of some reactive groups such as ? COOK, ? COONa, ? COOLi, and ? COOH. Lower electronegativity of the countercation favored higher total conversion and higher grafting percentage. The grafting percentage increased with the reaction time and concentration of reactive groups in the trunk polymer, but grafting efficiency varied very little under these conditions. In the bulk polymerization at 60°C., grafting efficiency was about 60%, but in the solution polymerization in toluene or dioxane, grafting efficiency was higher than in bulk or nitrobenzene.     

Ionic graft copolymerization. IV. Polymerization of β-propiolactone by acetic acid,p-toluenesulfonic acid,and their sodium salts

Acetic acid, toluenesulfonic acid, and their salts are used as four representative ionic catalysts for polymerization of β-propiolactone (βPL). They are classified as follows: sodium acetate is an anionic catalyst, acetic acid is a neutral one having more covalent character, sodium toluene sulfonate is a neutral one having more ionic character, toluenesulfonic acid is a cationic one. The neutral catalyst having more covalent nature is hardly dissociated, and therefore the rate of polymerization is quite small; however, dissociated ions consist of a higher neucleophilic anion and a higher electrophilic cation. On the contrary, the neutral catalyst having an ionic bond dissociates more easily, but the formed ions consist of the less reactive anion and cation. Therefore, it is of interest whether β-propiolactone is polymerized by a cationic mechanism or an anionic mechanism by these catalysts. The mechanisms of polymerizations of βPL by these neutral catalysts were studied on the basis of the different behaviors of polymerizations by the four catalysts described above. In the cationic polymerization by toluenesulfonic acid, the rate of polymerization was high, but the conversion reaches a low, limited value. In the anionic polymerization by sodium acetate, the rate of polymerization was high and the degree of polymerization of polymer was the highest. Acetic acid has the lowest catalyst activity and the degree of polymerization is also very small. It was found that the polymerization by sodium p-toluenesulfonate was accelerated in the presence of acrylic acid produced from βPL by hydrogen-transfer reaction.     

Ionic graft copolymerization. I. Homopolymerization of β-propiolactone by sodium acetate catalyst

The polymerization of β-propiolactone (βPL) by sodium acetate catalyst has been investigated. The polymerization behavior with monomer purified with calcium chloride was found to be a little different from that previously reported for this monomer. That is, poly-β-propiolactone (PβPL) obtained from βPL dried with CaCl₂ has a higher degree of polymerization than that obtained from conventionally treated βPL, and its infrared spectrum shows type II configuration, which differs from that reported in previous papers. Some chain transfer reaction is observed even for the polymerization of the CaCl₂–dried βPL; however, this is less important in toluene. The electronegativity of the anion or cation in catalyst greatly influences the rate of polymerization.     

Ionic graft copolymerization. VIII. Homopolymerization of β-propiolactone by radical catalysts in the presence of electron acceptors and application to graft copolymerization

The polymerization of β-propiolactone (βPL) induced by radiation and by radical catalysts, the influences of radical inhibitors and electron acceptors on this polymerization, and graft copolymerization were studied. It was found that βPL was polymerized by benzoyl peroxide in the presence of electron acceptors such as maleic anhydride and acrylonitrile. This polymerization method was applied to graft copolymerization. The electron donative trunk polymer containing ether groups was heated with benzoyl peroxide or was irradiated by γ-rays from Co⁶⁰ in the presence of maleic anhydride as the electron acceptor. βPL was added subsequently to form the graft copolymer.     

Radiation-Induced graft copolymerization,I. Graft copolymerization of methyl methacrylate onto nylon-6

The radiation-induced graft copolymerization of methyl methacrylate onto nylon fibers was investigated at room temperature. The homopolymer was separated by soxhlet extraction. The graft yield increases with increase of dose rate from 0.1768 to 0.7072 Mrad. The percentage of grafting increase with increasing monomer concentration. Addition of copper sulphate and a non-ionic surfactant, sodium lauryl sulphate, supresses the formation of homopolymer. The value of G_b, the number of branches per 100 eV of energy absorbed in the substrate polymer, and the value of α, the fraction of substrate polymer grafted, have been computed. A kinetic scheme has been suggested.     

Radiation-induced graft copolymerization of methacrylic acid onto polypropylene fibers VI. Dyeing behavior

The dyeing behavior of polypropylene-g-polymethacrylic acid fibers prepared by graft copolymerization of methacrylic acid onto polypropylene fibers by gamma-ray irradiation was evaluated for their dyeability characteristics using two basic dyes, rhodamine B and methylene blue. An increase in the dye uptake and moisture regain with the increase in graft content was observed. Such behavior has been attributed to the hydrophilicity imparted to polypropylene fiber by the presence of polar carboxyl groups in polymethacrylic acid grafts. The dependence of rate of dyeing on the percentage graft was evaluated. The diffusion coefficient of the fiber showed an increase with the increase in graft content and has been related to the structural changes occurring during grafting.     

Electrochemical polymerization of β‐naphthalene sulfonic acid

β‐Naphthalene sulfonic acid (β‐NSA) has been electrochemically polymerized in a mixed electrolyte of boron trifluoride diethyl etherate (BFEE) solution mixed with a certain amount of trifluoroacetic acid (TFA) or concentrated sulfuric acid (SA). The poly(β‐naphthalene sulfonic acid) (PNSA) film prepared from the medium of BFEE+TFA was partly soluble in methanol. On the other hand, the polymer obtained from the system of BFEE+SA was soluble in water and general polar organic solvents such as methanol, alcohol, and acetone. The structure of PNSA was examined by infrared and UV spectra. Fluorescent spectral studies indicate that the polymer is a blue light emitter with fluorescence quantum efficiency of ～ 4%. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1939–1944, 2004     

Graft copolymerization onto Tamarind Kernel Powder: Ceric(IV)‐initiated graft copolymerization of acrylonitrile

Tamarind Kernel Powder (TKP) is derived from the seeds of Tamarindus indica Linn., a common and most important tree of India. It is extensively used in cotton sizing, as a wet‐end additive in the paper industry, as a thickening, stabilizing, and gelling agent in the food industry. However, because of its fast biodegradability there is a need to prepare graft copolymers of TKP. The graft copolymerization of acrylonitrile (AN) onto TKP with ceric ammonium nitrate as a redox initiator in an aqueous medium has been studied. The reaction conditions were optimized to afford maximum percent grafting and percentage grafting efficiency of AN onto TKP, which was found to be 86% and 64%, respectively. Fourier Transform Infrared Spectrum of the grafted products showed an additional sharp absorption band at 2244 cm^?1 due to ? C?N stretching, thereby confirming the grafting of AN onto TKP. Scanning electron microscopy studies indicated change in contour of the polysaccharide on grafting and the thick polymeric coating of AN on the surface alongwith grafting of AN such that all the gap between polysaccharide particles have been closed. Thermal studies using thermogravimetric and differential gravimetric analyses confirmed that TKP‐g‐AN has overall high thermal stability than pure TKP. Reaction mechanism of grafting of acrylnitrile onto TKP is also proposed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Radiation-induced graft copolymerization of 2-hydroxyethyl methacrylate onto poly(γ-methyl-L-glutamate) membrane in ethanol solution

The radiation-induced graft copolymerization of 2-hydroxyethyl methacrylate (HEMA) onto poly(γ-methyl-L -glutamate) membranes was investigated in ethanol. The effects of dose, dose rate, concentration of HEMA, and temperature on the degree of grafting were studied. The initial rate of grafting copolymerization shows the following functional relationship equation: dG₀/dt = k[M]₀D˙^0.56. The average values of the apparent constants at 27 and 37°C for the initial rates of grafting are k₁ = 51 and k₂ = 91 G%h^−0.44 kGy^−0.56 mol⁻¹ L, respectively. The apparent activation energy of grafting copolymerization is E = 10.7 kcal/mol. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1575–1580, 1998     

Photo-induced graft copolymerization: XVI: Graft copolymerization of methyl methacrylate onto nylon-6 using isoquinoline-sulfur dioxide and α-picoline-sulphur dioxide charge-transfer complexes as photoinitiators

The photo-induced graft copolymerization of methyl methacrylate onto nylon-6 fiber was investigated using isoquinoline-sulfur dioxide and α-picoline-sulfur dioxide charge-transfer complexes as the photoinitiators. The graft copolymerization was carried out within the temperature range of 35–50°C and from the corresponding Arrhenius plot, the energy of activation has been evaluated. The effect of monomer, initiators, inhibitors, etc. on the graft yield has been investigated. The effect of solvent on the rate of grafting has also been investigated from which the chain-transfer constant (C_s) of the solvent has been evaluated. The kinetic data and other evidence indicate that the overall polymerization takes place by a radical mechanism. The suitable mechanism has been suggested and the kinetic rate expression has been derived.     

Electroinitiated copolymerization of N-vinylcarbazole and α-methylstyrene in a mixed biphasic medium

The electroinitiated copolymerization of N-vinylcarbazole and α-methylstyrene has been studied using a mixed biphasic system in which formamide together with some added electrolyte has been used as the polar phase and the monomer in bulk form or its solution in a nonpolar solvent as the nonpolar phase. The copolymer has been characterized by elemental analysis, and infrared and nuclear magnetic resonance spectroscopy. Molecular weights obtained from gel permeation chromatography were in the range of 20–25 × 10³. Generally the copolymer yield increased with increased applied current density. The effect of various other parameters such as dependence of copolymer yield on concentration of electrolyte and comonomer, temperature, and time of electrolysis have also been examined. The locus of polymerization is the anode compartment and a plausible mechanism based on the electrochemical formation of a radical-cation and a dication has been suggested.     

Cellulose graft copolymers. II. Graft copolymerization of ethyl acrylate with γ-irradiated cellulose from acetone–water systems

Ethyl acrylate was graft-copolymerized from acetone–water systems with γ-irradiated, purified cotton cellulose. The scavenging of the free radicals in the irradiated cellulose by water, acetone, and water–acetone systems was determined by electron spin resonance spectroscopy. The ESR spectra of free radicals, scavenged by water and acetone, were recorded by the use of a time-averaging computer attached to the ESR spectrometer, in which the ESR spectrum of the irradiated cellulose, which had been immersed in water and/or acetone, was electronically subtracted from the ESR spectrum of the irradiated cellulose control. For both water and acetone, the ESR spectra of the scavenged free radicals were singlets. This indicated that free radical sites formed on carbon C₁ or C₄ on radiation-initiated depolymerization, which would generate singlet ESR spectra, were readily accessible to these solvents. The maximum scavenging of the radicals was observed when irradiated cellulose was immersed in acetone–water solution which had a composition of 25/75 vol-%. The scavenging of the free radicals in irradiated cellulose when immersed in acetone–water solutions was less than when immersed in methanol–water solutions. Also, the extent of graft copolymerization of ethyl acrylate from acetone solutions with irradiated cellulose was less than that of ethyl acrylate from methanol solutions. These differences were probably due to differences in the diffusion rates of acetone and methanol into the cellulosie structure. The Trommsdorff-type effect in the acetone solutions would be less than in the methanol solutions, since acetone is a better solvent for poly(ethyl acrylate) than methanol.     

Cellulose graft copolymers. I. Graft copolymerization of ethyl acrylate with γ-irradiated cellulose from methanol–water systems

Ethyl acrylate was graft-copolymerized with γ-irradiated, purified cotton cellulose from methanol–water systems. The accessibility of the free radicals in the irradiated cellulose to water, methanol, ethyl acrylate, and methanol–water solutions was determined by electron spin resonance spectroscopy. The maximum scavenging of the radicals was recorded with the irradiated cellulose was immersed in methanol–water solution which had a composition of 50/50 vol-%. When ethyl acrylate was added to methanol–water solution (50/50 vol-%), maximum grafting on the irradiated cellulose occurred at a concentration of ethyl acrylate of about 20 vol-%. As the concentration of ethyl acrylate was decreased, maximum grafting occurred in solutions containing less than 50 vol-% methanol. It was also noted that maximum grafting of ethyl acrylate in methanol–water solutions to irradiated cellulose occurred at boundry conditions, that is, conditions where the ternary mixture was still one phase, slightly different from compositions which caused the mixture to separate into two phases. From methanol solution, maximum grafting occurred at a concentration of ethyl acrylate of 80 vol-%. The extent of grafting from methanol was less that obtained from methanol–water solutions at lower concentrations of ethyl acrylate. The accelerative effects of water was considered to be due to the Trommsdorff effect.     

Plasticization of cellulose diacetate by graft copolymerization of ε‐caprolactone and lactic acid

Graft copolymerization of ε‐caprolactone (CL) and lactic acid (LA) onto cellulose diacetate (CDA) at the residual hydroxyl positions was conducted to obtain thermoplastic CDA. The effects of the reaction temperature and time and the CL/LA molar ratio in the feed on the progress of the graft copolymerization were investigated. The molecular weight of CDA was increased by this graft copolymerization. The oxycaproyl and lactyl molar substitutions (MS_CL and MS_LA, respectively) in grafted CDA (g‐CDA) were determined through ¹H‐NMR spectral analysis. These MS values were controllable by changing the reaction conditions adequately. The flow temperature and melt viscosity of g‐CDA decreased with an increase in the total substitution of MS_CL and MS_LA, and transparent polymer sheets could be obtained from the resulting g‐CDA by hot pressing at around 200°C without adding any plasticizer. The mechanical properties of the molded g‐CDA samples varied widely, depending on the different combinations of the MS_CL and MS_LA values; the g‐CDA sheets became elastic when the MS_CL was larger than the MS_LA, and their tensile strengths were enhanced as the MS_LA was increased. It was thus found that CDA was successfully plasticized by this graft copolymerization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2621–2628, 2002     

Polymerization of α, α-disubstituted-β-propiolactones and lactams. 9. ABA block copolymers of α-methyl-α-butyl-β-propiolactone and pivalolactone

ABA block copolymers were prepared by the anionic polymerization of α-methyl-α-butyl-β-propiolactone, MBPL (B block), and pivalolactone, PL (A blocks). The MBPL block had a very low decree of crystallinity and a glass temperature of ? 13°C, so phase separation with extensive crystallization of the PL blocks gave thermoplastic elastomers when the MBPL block constituted the principal and continuous phase. The observed crystallinity and melting point of 40–45°C in the MBPL homopolymer have not been previously reported. Measurements were obtained by electron microscopy of the initial size distribution of the PL domains as a function of copolymer composition and degree of polymerization, and on the effect of annealing on this parameter. Tensile strengths and elongations at break were both less than those previously observed for equivalent ABA block copolymers of PL and α-methyl-α-propyl-β-propiolactone.