Study on ketalization reaction of polyvinylalcohol by ketones. V. The film properties of polyvinylketals obtained by aliphatic ketones

The physical and chemical properties of polyvinylketals (PVKL) prepared from seven aliphatic ketones [acetone, methyl ethyl ketone (MEK), methyl n-propyl ketone (nPK), methyl i-propyl ketone (iPK), methyl n-butyl ketone (nBK), methyl i-butyl ketone (iBK), methyl t-butyl ketone (tBK)] were studied. The moisture regain and water vapor permeability of PVKL films decrease in the following order: acetone > MEK > nPK > iPK ≒ nBK > iBK > tBK. The contact angle measurements revealed that this order is determined by the surface free energy of films, which depends upon the kind of the original ketones. PVKL (acetone) with low ketalization degree was not soluble in neutral water and had lower moisture regain than PVA. As shown in X-ray analysis, the molecular orientation was not random, the crystalline part of PVA remaining. Thus, it becomes clear that behavior of PVKL in water is affected not only by the hydrophobicity of film surface, but also by the crystallinity of PVKL.     

Study of ketalization reaction of poly(vinyl alcohol) by ketones. VI. Reaction between poly(vinyl alcohol) and cyclic ketones and behavior of poly(vinyl ketal) in water

The ketalization reaction of poly(vinyl alcohol) (PVAL) by cyclic ketones, with dimethyl sulfoxide (DMSO) as solvent, in the presence of an acidic catalyst in homogeneous system, was carried out. The synthesis of poly(vinyl ketals) was thus successfully performed, except for the case of poly(vinyl ketal) highly ketalized by cyclohexanone; these poly(vinyl ketals) with a ketalization degree of more than 60 mol % were insoluble in DMSO, and, thus, the reaction could not be carried out in a homogeneous system. The equilibrium constant at 40°C was ca. 0.50 in the case of cyclohexanone and ca. 0.35 in the case of cyclopentanone, some 10–50 times higher compared with the case of aliphatic ketones. Because the heat of reaction is 7.5 kcal/mol in all ketones, all ketalization reactions are considered to proceed by the same reaction mechanism. Films prepared from the poly(vinyl ketals) were soaked in water, and hydrolysis, degree of swell, and solubility were measured. The dissolution time of films is affected by the kind of the ketones, ketalization degree, and the pH of water, which reveals that deketalization reaction proceeds proportionally to the proton concentration. It is more difficult to dissolve poly(vinyl ketal) obtained by cyclohexanone than that by cyclopentanone. The rate of hydrolysis of poly(vinyl ketal) film obtained by cyclohexanone is nearly equal to that by methyl butyl ketone, and that by cyclopentanone is nearly equal to that by methyl propyl ketone. The contact angle, surface free energy, moisture regain, and water permeability of poly(vinyl ketal) films were measured. All the results show that poly(vinyl ketal) obtained from cyclohexanone is a more hydrophobic polymer than that from cyclopentanone. The hydrophobicity seems to depend upon the kind of the original ketones and the flexibility of the ring. © 1993 John Wiley & Sons, Inc.     

Study on ketalization reaction of polyvinylalcohol by ketones. III. Reaction between polyvinylalcohol and methyl ethyl ketone and behavior of polyvinylketal in water

Ketalization reaction of polyvinylalcohol (PVA) by methyl ethyl ketone (MEK), dimethyl-sulfoxide (DMSO) as solvent, under the presence of acidic catalyst, in homogeneous system was carried out, and the synthesis of polyvinylketal with any ketalization degree was successfully performed. The reaction mechanism of PVA with MEK is identical with that with acetone: for both cases, the equilibrium constant is ca. 0.07 at 40°C and the heat of reaction is 7.5 kcal/mol. Films prepared from the polyvinylketal were soaked in water and degree of swell, solubility, and hydrolysis of films were measured. The reaction of film with water, in acidic side, easily proceeds, and at first the film swells; then, as deketalization reaction proceeds, the film dissolves in water. With polyvinylketal of the ketalization degree of above 15 mol %, dissolution time is controlled by both ketalization degree and pH of water, which reveals that deketalization reaction proceed proportionally to proton concentration at 37°C. On the other hand, in the neutral condition where hydrolysis does not proceed at all, polyvinylketal of ketalization degree of 10–40 mol % dissolves in water at 0°C. The polyvinylketal obtained by MEK is more stable in water than that from acetone since MEK has hydrophobicity.     

Study on ketalization reaction of poly(vinyl alcohol) by ketones. VII. Reaction between poly(vinyl alcohol) and aromatic ketones and behavior of poly(vinyl ketal) in water

The ketalization reaction of poly(vinyl alcohol) (PVA) by aromatic ketones, with dimeth-ylsufoxide (DMSO) as solvent, under the presence of an acidic catalyst in homogeneous system, was carried out. The synthesis of poly(vinyl ketal) (PVKL) for the case of phenylacetone and benzylacetone was thus successfully performed, but for the case of acetophenone was performed only with a ketalization degree of a few molecular percent, and for the case of benzophenone it could not be performed at all. It seems that these different behaviors in synthesis are due to steric hindrance of the bulky side chain of ketones. The equilibrium constant at 40°C was ca. 0.12. in the case of phenylacetone and benzylacetone, and the value is somewhat higher compared with that of aliphatic ketones, but somewhat lower compared with the case of cyclic ketones. Because the heat of reaction is 7.5 kcal/mol in these two aromatic ketones, all ketalization reactions are considered to proceed by the same reaction mechanism. The rate of hydrolysis, contact angle, surface free energy, moisture regain, and water vapor permeability of PVKL films were measured. All results show the PVKL obtained from phenylacetone is nearly equal to PVKL obtained from methyl n-butyl ketone. However PVKL obtained from benzylacetone shows different behavior compared with other ketones, because the side chain of benzylacetone is flexible and bulky. The hydrophobicity of PVKL seems to depend upon the kind of the original ketones and the flexibility of the side chain. © 1995 John Wiley & Sons, Inc.     

Study on ketalization reaction of polyvinylalcohol by ketones. II. Behavior of polyvinylketal,obtained by acetone,in water

Films prepared from polyvinylketal obtained by acetone, with different ketalization degree, were soaked in water and degree of swell, solubility, and hydrolysis of films were measured. The reaction of film with water, in acidic side, easily proceeds even at lower temperature ranges, and at first film swells, and then as deketalization reaction proceeds the film dissolves in water. Polyvinylketal of the ketalization degree below 5 mol% behaves similarly to polyvinylalcohol (PVA). With polyvinylketal of the ketalization degree of above 5 mol%, dissolution time is controlled by both ketalization degree and pH of water which reveals that deketalization reaction proceeds proportional to proton concentration. On the other hand, in neutral or alkaline conditions where hydrolysis does not proceed at all, polyvinylketal of ketalization degree of 15–60 mol% dissolves in water at 0°C and therefore it can be considered as a kind of water-soluble high polymer. Polyvinylketal dissolves more easily in water at lower temperatures than at higher temperatures.     

Study on ketalization reaction of polyvinylalcohol by ketones. I. Reaction between polyvinylalcohol and acetone

Ketalization reaction of polyvinylalcohol (PVA) by acetone, dimethylsulfoxide (DMSO) as solvent, under the presence of acidic catalyst, in homogeneous system was carried out and the synthesis of polyvinylketal with any ketalization degree was successfully performed. This reaction proceeds in bimolecular reaction, the equilibrium constant is ca. 0.07 at 40°C and roughly 10^?5 less compared with the acetalization reaction between PVA and aldehydes. Synthesis in aqueous media is difficult. However, the heat of reaction for both cases is 7.5 kcal/mol and both reactions are considered to proceed in an identical reaction mechanism. Ketalization reaction starts from isotactic OH portion and proceeds finally to syndiotactic OH portion, however, 100% ketalization is extremely difficult. The effects of water on reaction was confirmed both from theoretical and experimental viewpoints, and even though the presence of water lowers the degree of ketalization, it was observed that the presence of water below 0.1 mol against 1 mol of PVA will not significantly affect final ketalization degree. Polyvinylketals thus obtained are soluble in DMSO, dimethylformamide (DMF), and alcohols.     

A novel approach to hydrolyzable polyvinylketal from poly(vinyl alcohol) and acetone under phase transfer catalyst conditions

Ketalization reaction of poly(vinyl alcohol) (PVA) by acetone under acidic-catalyst/phase-transfer-catalyst was carried out easily and the structure of the product both swelled and dissolved in dimethyl sulfoxide-d₆ (DMSO-d₆) was confirmed, which then indicated the structural change in the product polyvinylketal (PVKT) due to its hydrolysis in water, by NMR measurements. The effect of catalysts on reaction was probed from experimental viewpoint, compared with the theoretical calculation applicable to the previous classical method. It was observed that high ketalization degree PVKT was obtained with the presence of water and the effect of water on reaction was also probed in the present method, which may result in further application in the total syntheses of complex macromolecules from polyols and ketones. The behavior of PVKT in water under different conditions, which is very similar to that described in previous report, was also studied, as well as the specific viscosity (η_sp) of PVKT solution, and proper explanation is proposed. And the present study may lead to a further investigate of attractive intrinsic properties of PVKT.     

Isothermal vapour-liquid equilibria in binary mixtures of ketones and alkanes

Vapour-liquid equilibrium data were determined at 65 °C for five binary mixtures of ketones and n-alkanes. The systems studied were acetone/n-decane, methyl ethyl ketone/n-hexane, methyl ethyl ketone/n-octane, diethyl ketone/n-hexane and di-n-propyl ketone/n-hexane. Activity coefficients were evaluated taking into account vapour phase imperfections, and are presented.     

Sorption and transport of linear and branched ketones in biaxially oriented polyethylene terephthalate

Equilibrium sorption and kinetics of acetone, methyl ethyl ketone (MEK), methyl n-propyl ketone (MnPK), and methyl i-propyl ketone (MiPK) uptake in uniform, biaxially oriented, semicrystalline polyethylene terephthalate films were determined at 35 °C and low penetrant activity. Sorption isotherms for all penetrants were well described by the dual-mode sorption model. Sorption and desorption kinetics were described either by Fickian diffusion or a two-stage model incorporating Fickian diffusion at short times and protracted polymer structural relaxation at long times. Diffusion coefficients and equilibrium solubility at fixed relative pressure decreased in the following order: acetone>MEK>MnPK>MiPK. Diffusion coefficients for each penetrant increased with increasing penetrant concentration.     

Studies of reactions with polymers. III. Syntheses and properties of poly(vinyl alcohol) graft terpolymers

A condensation-coupling reaction through esterification is performed between the hydroxy groups of poly(vinyl alcohol) (PVA) and the anhydride groups of methyl methacrylate (MMA)-co-maleic anhydride (MA) copolymer to produce the PVA-g-MMA/MA graft terpolymer. The MMA-co-MA copolymer was obtained by copolymerization of MA and MMA in dimethyl sulfoxide by using azobisisobutyronitrile as initiator. The structure of reaction products was confirmed by infrared analysis, and the dependence of composition, viscosity, and yield of the graft terpolymer on the MA content in MMA-co-MA as well as the concentration of the reactants fed were investigated. Mechanical properties, water content, and gel content of the membranes of terpolymers were measured over a wide range of compositions. PVA-g-MMA/N-ethylol maleimide was also synthesized by reacting the residual anhydride groups on PVA-g-MMA/MA with ethanol amine, this reaction proceeds through the PVA-g-MMA/N-ethylol maleamic acid intermediate.     

Synthesis of sulfone-modified poly(vinyl alcohol) and its application for permselective membrane of sulfur dioxide

The Michael type addition reaction of poly(vinyl alcohol) (PVA) with a series of vinyl sulfones, namely methyl vinyl sulfone, ethyl vinyl sulfone, and t-butyl vinyl sulfone, was performed with NaOH as catalyst to produce 2-(alkylsulfonyl)ethyl PVA derivatives. The high permselectivity of sulfur dioxide against nitrogen and oxygen was achieved through these sulfone-modified PVA membranes.     

Revisiting the thermal relaxations of poly(vinyl alcohol)

The molecular dynamics of poly(vinyl alcohol) (PVA) were studied by dielectric spectroscopy and dynamic mechanical analysis in the 20–300°C range. The well-established plasticizing effect of water on the glass-transition temperature (T_g) of PVA was revisited. Improper water elimination analysis has led to a misinterpretation of thermal relaxations in PVA such that a depressed T_g for wet PVA films (ca. 40°C) has been assigned as a secondary β relaxation in a number of previous studies in the literature. In wet PVA samples, two different Vogel–Fulcher–Tammann behaviors separated by the moisture evaporation region (from 80 to 120°C) are observed in the low- (from 20 to 80°C) and high- (>120°C) temperature ranges. Previously, these two regions were erroneously assigned to two Arrhenius-type relaxations. However, once the moisture was properly eliminated, a single non-Arrhenius α relaxation was clearly observed. X-ray diffraction analysis revealed that the crystalline volume fraction was almost constant up to 80°C. However, the crystallinity increased approximately 11% when temperature increased to 180°C. A secondary β_c relaxation was observed at 140°C and was related to a change in the crystalline volume fraction, as previously reported. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Graft copolymers of cellulose and vinylic ketones. I. Preparation of poly(methyl vinyl ketone)–cotton cellulose copolymers

The graft copolymerization reaction of methyl vinyl ketone from several solvents with fibrous cotton cellulose, preirradiated to a dosage of 5.2 × 10¹⁹ eV/g with γ-radiation from ⁶⁰Co, was investigated. Solvents included water, methanol, N,N-dimethyl formamide, and several combinations of these solvents. From water a maximum yield of copolymer product was obtained after 2 hr at 25°C. The addition of methanol to aqueous solutions of methyl vinyl ketone, in all concentrations, inhibited the graft copolymerization reaction. The addition of a small amount of N,N-dimethylformamide to aqueous solutions of the monomer increased the rate of the copolymerization reaction; however, the addition of large amounts of N,N-dimethylformamide to these solutions also inhibited the reaction. From solutions of methanol or N,N-dimethylformamide and monomer, little or no copolymerization of monomer with irradiated cellulose occurred. The copolymer products exhibited a strong infrared absorption band at 5.85 μ which is characteristic of the ? C?O group of the grafted poly(methyl vinyl ketone). Fibrous copolymer yarns exhibited increased yarn number and decreased breaking strength and average stiffness, as compared with unmodified cotton yarns.     

Syntheses of photocrosslinkable polymer from modified poly(methyl vinyl ketone)

Photocrosslinkable polymer is prepared from amorphous poly(methyl vinyl ketone) (A-PMVK) obtained by anionic polymerization of methyl vinyl ketone. The reaction of A-PMVK with cinnamoyl chloride proceeds in pyridine at 50°C. The photosensitivity of the polymer obtained is measured by infrared and Ultraviolet photometry. The polymer is of a crosslinkable type and forms cyclobutane linkage by ultraviolet irradiation. The polymer is coated on a lithographic aluminum plate and exposed to arc and high-pressure mercury lamps. Development is with benzene, and standard inking by lithography is applied. The imaging area on the plate is stable and harder than poly(vinyl cinnamate), due to intra- and intermolecular cyclization of the main chain. Many good reproductions are produced in the lithographic proofing machine. The photosensitive polymer obtained by A-PMVK is very useful in relief plates requiring etching.     

Miscibility behavior of blends of poly(alkyl methacrylate)s with poly(p-methylstyrene-co-methacrylonitrile)

The miscibility behavior of various poly(p-methylstyrene-co-methacrylonitrile) (pMSMAN)/poly(alkyl methacrylate)s blends was studied using differential scanning calorimetry. pMSMAN is miscible with poly(methyl methacrylate), poly(ethyl methacrylate), poly(n-propyl methacrylate), poly(isopropyl methacrylate), and poly(n-butyl methacrylate) over certain copolymer composition ranges, but is immiscible with poly(isobutyl methacrylate) and poly(n-amyl methacrylate). The width of the miscibility window decreases with increasing size of the pendant ester group of the poly(alkyl methacrylate), and is wider than that of the corresponding poly(p-methylstyrene-co-acrylonitrile) blend system. Various segmental interaction parameters are calculated using a binary interaction model. © 1995 John Wiley & Sons, Inc.     

Graft polymerization of vinyl acetate onto starch. Saponification to starch–g–poly(vinyl alcohol)

Graft polymerizations of vinyl acetate onto granular corn starch were initiated by cobalt-60 irradiation of starch-monomer-water mixtures, and ungrafted poly(vinylacetate) was separated from the graft copolymer by benzene extraction. Conversions of monomer to polymer were quantitative at a radiation dose of 1.0 Mrad. However, over half of the polymer was present as ungrafted poly-(vinyl acetate) (grafting efficiency less than 50%), and the graft copolymer contained only 34% grafted synthetic polymer (34% add-on). Lower irradiation doses produced lower conversions of monomer to polymer and gave graft copolymers with lower % add-on. Addition of minor amounts of acrylamide, methyl acrylate, and methacrylic acid as comonomers produced only small increases in % add-on and grafting efficiency. However, grafting efficiency was increased to 70% when a monomer mixture containing about 10% methyl methacrylate was used. Grafting efficiency could be increased to over 90% if the graft polymerization of vinyl acetate-methyl methacrylate was carried out near 0°C, although conversion of monomers to polymer was low and grafted polymer contained 40-50% poly(methyl methacrylate). Selected graft copolymers were treated with methanolic sodium hydroxide to convert starch–g–poly(vinyl acetate) to starch–g–poly(vinyl alcohol). The molecular weight of the poly(vinyl alcohol) moiety was about 30,000. The solubility of starch–g–poly(vinyl alcohol) in hot water was less than 50%; however, solubility could be increased by substituting either acid-modified or hypochlorite-oxidized starch for unmodified starch in the graft polymerization reaction. Vinyl acetate was also graft polymerized onto acid-modified starch which had been dispersed and partially solubilized by heating in water. A total irradiation dose of either 1.0 or 0.5 Mrad gave starch–g–poly(vinyl acetate) with about 35% add-on, and a grafting efficiency of about 40% was obtained. A film cast from a starch–g–poly(vinyl alcohol) copolymer in which homopolymer was not removed exhibited a higher ultimate tensile strength than a comparable physical mixture of starch and poly(vinyl alcohol).     

FTIR-ATR studies of the sorption and diffusion of acetone:water mixtures in poly(vinyl alcohol)-clay nanocomposites

The simultaneous ingress of acetone and water into dried PVOH-clay nanocomposites containing 2.5 wt% or 5 wt% of well dispersed Na-Cloisite, using FTIR-ATR, has been compared with that into pure PVOH films. The rate at which water and acetone moved through the PVOH films is significantly reduced (i) at high acetone concentrations and (ii) when clay is incorporated in the PVOH film. For example, it takes 9 min and 17 min for water and acetone, respectively, to saturate a 25 ± 5 μm PVOH film containing 2.5 wt% of well dispersed clay when the acetone:water ratio is 90:10 v/v compared with ca. 1 min for a pure PVOH film when the acetone:water ratio is 70:30 v/v. The presence of significant quantities of water in the PVOH (nanocomposite) films was necessary before acetone began to permeate the film. The acetone entering the evanescent field was always highly hydrated even if the water content of the reservoir in contact with the film was low. There was no substantial evidence that the presence of clay altered the way in which the PVOH interacted with the acetone:water mixtures. The clay only acted to increase the tortuosity of the path through the film to the ATR prism.     

The electric conductivity of poly(ethyl vinyl ketone) film reacted with phosphoryl chloride

Summary The reaction of poly (ethyl vinyl ketone) with active chlorides in petroleum ether was followed by the electric conductivity measurement. Phosphoryl chloride was found to be an effective reagent to produce a highly conjugated system with an apparent specific conductivity of the order of 10^{–2 –1}cm^–1 in petroleum ether. The reaction temperature seems to be important for the electric conductivity of the product, the higher the reaction temperature, the lower the electric conductivity of the reacted film.     

Perylene dye photodegradation due to ketones and singlet oxygen

The photodegradation rate of a perylene dye (Lumogen F Yellow 083) in methyl isobutyrate was found to increase with ketone concentration for two different ketones. Of the ketones employed, methyl pyruvate, an impurity in methyl methacrylate, was found to be particularly deleterious to dye stability. In agreement with other published studies, the addition of the anti-oxidant DABCO (1,4-diazabicyclo-[2.2.2] octane) to the dye matrix was found to increase dye stability; however when ketones were present, DABCO lead to increased photodegradation. These results highlight the importance of removing ketone impurities from dye matrices during production of Luminescent Solar Concentrators (LSCs).     

Poly(vinyl alcohol) and poly(vinyl amine) blend membranes for isopropanol dehydration

Blended membranes of hydrophilic polymers poly(vinyl alcohol) (PVA) and poly(vinyl amine) (PVAm) were prepared and crosslinked with glutaraldehyde. The prepared membranes were characterized using infrared (attenuated total reflection mode) spectroscopy, differential scanning calorimetry, X‐ray diffractometry, and scanning electron microscopy measurements. Pervaporation performances of the membranes were evaluated for the separation of water‐isopropanol (IPA) mixtures. As the PVAm content increased from PVAm0 to PVAm1.5, the flux through a 70 μm film increased from 0.023 to 0.10 kg/m² h at an IPA/water feed ratio of 85/15 at 30 °C. The driving force for permeation of water increased due to the temperature but it has no effect on IPA permeation. Activation energies for the permeation of IPA and water were calculated to be 17.11 and 12.46 kJ/mol, respectively. Controlling the thickness of the blend membrane could improve the permeation flux with only a marginal reduction in the separation factor. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45572.