Cerium–initiated Polymerisation of some Vinyl Compounds in Cellulose Fibres

The effects of monomer and initiator concentration on the graft polymerisation of acrylic acid and of 2–vinylpyridine in viscose rayon and cotton, initiated by ceric ammonium sulphate in dilute sulphuric acid, have been examined. Polymerisation of acrylic acid occurs less readily in cotton treated with caustic soda, and in acid–modified cotton, than in the parent fibre. Neither preliminary treatment with initiator nor partial oxidation with sodium periodate affects the extent of subsequent grafting of poly(acrylic acid) to viscose rayon under selected conditions. The rate of polymerisation of 2–vinylpyridine in cellulose is lower than that of acrylic acid, but polymerisation is greatly accelerated by substituting dilute perchloric acid for sulphuric acid as the solvent. This is apparently a manifestation of the ‘gel effect’ and has been observed with other basic monomers that form insoluble polymer perchlorates. Proof is offered that both acrylic acid and 2–vinylpyridine afford true graft copolymers with cellulose. These polymers do not improve the mechanical properties of viscose rayon filaments. Support for the view that oxidative C₍₂₎–C₍₃₎ bond–fission participates in the initiation of polymerisation in cellulose by eerie salts is provided indirectly by the isolation of adipaldehyde as a major product from the oxidation of cyclohexane–trans–l, 2–diol with ceric ammonium nitrate.     

Dialysis membranes from polyethylene films grafted with acrylic acid

Low‐density polyethylene‐g‐poly(acrylic acid) membranes were prepared by the direct radiation grafting of aqueous acrylic acid solutions (containing Mohr's salt) onto low‐density polyethylene films and were irradiated at two different irradiation doses (2 and 3 Mrad) at a dose rate of 0.02 Mrad/h. Two series of polyethylene‐g‐poly(acrylic acid) membranes with 100 and 150% grafting were obtained. The free carboxylic acid groups in the grafted films were converted into the corresponding acrylates by reactions with different metal salts. The swelling (water uptake) and dialysis permeability of glucose and urea through the grafted membranes in different metal‐ion forms were investigated. The prepared membranes showed good permeability to both solutes, which increased as the hydrophilicity of the membrane increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 10–14, 2004     

Solvent‐free diazotization–azidation of aryl amine using a polymer‐supported azide ion

Crosslinked poly (4‐vinylpyridine)‐supported azide ion was used as an effective azidating agent for deazodination of stable arenediazonium salts under solvent‐free conditions in high yields. The diazotization of aromatic amines was prepared by grinding the combination of an aromatic amine, sodium nitrite (NaNO₂), p‐toluene sulfonic acid (p‐TsOH), and 0.2 mL H₂O in a mortar. Grinding was continued for deazodination–azidation of the obtained relatively stable diazonium salts, with addition of crosslinked poly (4‐vinylpyridine) supported azide ion to obtain the corresponding aryl azides. The spent polymeric reagents can usually be removed and regenerated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Acrylic acid containing copolymers as reactive compatibilitzers for toughening nylon 6

Nylon 6 has been toughened by rubber particles that were dispersed within the matrix via additives that physically interact with the elastomer phase but chemically react with the polyamide phase. To disperse a core-shell impact modifier having a poly(methyl methacrylate) or PMMA shell, most of the work presented is based on the use of a styrene/acrylic acid copolymer containing 8 wt% acrylic acid, SAA8. SAA8 is miscible with PMMA and should located in the PMMA grafted chains of the impact modifier while chemically reacting with the nylon 6 matrix; hence, it should aid in both the dispersal and strenghtening the modifier-matrix interface. Microscopy and mechnical properties confirm that SAA8 does function in this way but less effectively than styrene/maleic anhydride copolymers, which are also miscible with PMMA but evidently react more effectively with the polyamides. The use of ethylene/acrylic acid copolymer for dispersal of the coreshell impact modifier and a styrene/ethylene-butene/styrene block copolymer in nylon 6 was also briefly considered. Low-temperature toughness of the blends proved to be a much more critical test of the effectiveness of such additives than room temperature impact strenght.     

Compatibilization of poly(vinylidene fluoride)/nylon 6 blends by carboxylic acid functionalization and metal salts formation. I. Grafting reactions and morphology

An investigation was carried out to determine the feasibility of producing compatibilized blends of PVDF and nylon 6 using a procedure involving the grafting of carboxylic acid groups on the chains of either polymer component and, subsequently, producing the corresponding metal salts. The grafting reactions were carried out by irradiating the polymer with γ-rays at 15 kGy, followed by treatments in aqueous solutions of methacrylic acid. These conditions were established from preliminary work which also revealed that this monomer gives higher grafting yields than acrylic acid. The grafted polymers were found to have a heterogeneous structure, attributed to the presence of oligomeric, rather than unitary, side groups. Nevertheless, these modifications of the polymer chains were found to give rise to well-compatibilized blends, containing co-continuous phases which became much finer through the addition of zinc acetyl acetonate. FTIR analysis showed that the enhanced compatibilization resulted from the reactions between the acid groups in the PVDF component and the terminal amine groups of the polyamide chains. Since the addition of zinc acetyl acetonate was found to reduce the yield of amidized groups, it was inferred that the enhanced compatibilization has resulted from the complexation of zinc cations with the amide groups in the nylon 6 chains, which are shared with the carboxylate anions of the grafted PVDF component. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1911–1923, 1997     

Toughening of nylon 6 with grafted rubber impact modifiers

Recent work has shown that nylon 6/acrylonitrile–butadiene–styrene (ABS) blends can be made tough by the addition of some polymer additives that are chemically reactive with nylon 6 and physically compatible with the styrene-acrylonitrile copolymer (SAN) phase of ABS. Imidized acrylic polymers (IA) represent a successful example of such additives that improve the dispersion of ABS in the nylon 6 matrix and render the blends tough. This article examines the possibility of toughening nylon 6 with ethylene/propylene/diene elastomer grafted with SAN copolymer (EPDM-g-SAN). This EPDM-g-SAN consists of 50% rubber and 50% SAN by weight. However, it was found that the same IA that works well to disperse ABS materials of similar rubber content is not as effective for EPDM-g-SAN, primarily because the EPDM forms the continuous phase, not SAN, and, thus, interfaces with nylon 6 during melt blending. Maleated elastomers like maleic anhydride grafted ethylene–propylene copolymer (EPR-g-MA) and styrene–(ethylene-co-butylene)–styrene triblock copolymer (SEBS-g-MA) were more effective for dispersing EPDM-g-SAN in the nylon 6 matrix than IA. Various mechanisms that improve the dispersion are discussed. © 1995 John Wiley & Sons, Inc.     

Wide-angle X-ray diffraction studies of nylon–ionomer blends

Blends of nylon 6 with poly(acrylic acid) polyacrylamide, poly(ethylene-co-acrylic acid), poly(ethylene-co-vinyl alcohol), poly(acrylamide-co-acrylic acid), and polypropylene were prepared by melt blending. Annealing treatments included treatments in Vacuum, in water, and in 20% formic acid at various temperatures. WAXS (wide-angle X-ray scattering) patterns of melt chips and of undrawn, drawn and textured yarns were obtained. The melt chips of 100% nylon 6 crystallize in the α form while the chips of all the blends exhibit a single diffracton ring. All the blends behave similarly during different annealing treatments. When annealed in 20% formic acid at 102°C, the α structure results. The as-spun fibers of nylon 6 and of the blends with poly(acrylamide-co-acrylic acid) and poly(ethylene-co-vinyl alcohol) exhibit a broad diffraction maximum in the region 2θ = 19–25°. The α content and its purity increase with increasing severity of the annealing treatment. The as-spun fibers of the blend with poly(acrylic acid), on the other hand, exhibit a highly oriented γ structure which is highly resistant to conversion to the α from during the annealing treatments. Only when treated in 20% formic acid at 102° does the pure α form result. The drawn textured yarns of nylon 6 exhibit both the α and the γ forms. However, the γ content of the textured yarns from the blends varies with the type and concentration of the additives. The textured yarns from the blends with low levels (0.125%) of poly(acrylic acid) have a very high α content. It is very unusual that the as-spun fibers with almost pure γ structure, when drawn, produce a structure with a high α content.     

Characterization of a nylon 6/poly(methyl acrylate) copolymer produced by radiation grafting

Acrylic acid has been grafted onto nylon 6 by the mutual γ-irradiation technique. Methods are described for removing poly(acrylic acid) homopolymer and ungrfted nylon, the latter involving intermediate conversion to the calcium ionomer. The pure graft copolymer in its methylated form, viz., nylon 6/poly(methyl acrylate), NY/PMA, was characterized by light scattering in mixed solvents to yield the true molecular weight (3.2 × 10⁶) as well as the molecular weights M_PMA(domain) and M_NY(domain) of the PMA and NY portions, respectively. The molecular weight M_PMA of the grafts was measured after hydrolysis of the backbone, and the molecular weight M_NY of the backbone was determined via a previously devised indirect procedure. Comparisons of M_PMA(domain) with M_PMA and of M_NY(domain) with M_NY gave ? 7 nylon chains and ? 17 poly(methyl acrylate) chains per copolymer molecule. Chain transfer and bimolecular terminatin during grafting are proposed as probable contributory factors to the branched structure of the copolymer.     

Antibacterial and Bacterium Adsorbing Macromolecules

Currently studies on antibacterial macromolecules, i. e., bactericidal and bacteriostatic ones, have been made to develop a new utilization field of polymeric materials. In these studies, there are immobilizations of iodine to quaternary ammonium salts, antibiotics, antibacterial groups to macromolecular substances, as well as syntheses of polymers with quaternary ammonium salts, biguanide groups, quaternary pyridinium salts, sulphonium salts, phosphonium salts, and other antibacterial groups. On the other hand, studies have been made of bacterium adsorbing macromolecules, which can remove by adsorbing bacterial cells in water. The macromolecules are the ones based on poly(4‐vinylpyridine‐co‐divinylbenzene), crosslinked poly(3‐ and 4‐chloromethylated styrene‐g‐amine), and poly(glycidyl methacrylate‐g‐amine), as well as filters and microporous membranes are covered with a macromolecule based on quaternized poly(4‐vinylpyridine‐co‐styrene). Here, a review is made of the syntheses and preparation of the respective macromolecules, as well as of their antibacterial activities and the bacterium adsorbing activities.     

Grafting reactions onto poly(organophosphazenes). IV. Light-induced graft copolymerization of organic polymers containing free acid or basic functionalities onto poly[bis(4-benzylphenoxy)phosphazene]

The light-induced graft copolymerization of acrylic acid, methacrylic acid, and 4-vinylpyridine onto poly[bis(4-benzylphenoxy)phosphazene] films to prepare new grafted phosphazene copolymers containing acid and basic functionalities is reported. The process was carried out in monomer/methanol mixtures in the presence of benzophenone or benzoin ethyl ether as photosensitizers by selective excitation of these last species. The yield of the grafting processes was evaluated as a function of the monomer concentration in the reaction medium, type of photoinitiator, and characteristics of the grafted organic monomers. The acid functions inserted in poly[bis(4-benzylphenoxy)phosphazene]-g-poly(meth)acrylic acid grafted copolymers, and the basic groups of the poly[bis(4-benzylphenoxy)phosphazene]-g-poly-4-vinylpyridine substrates were allowed to interact with basic and acid dyes, respectively, to form permanently colored polymeric films. The photoactivity of these films as substrates for the photosensitized production of singlet oxygen was tested. © 1995 John Wiley & Sons, Inc.     

Graft copolymerization of acrylic acid to nylon 6 by mutual irradiation. II. The influence of cupric ions

In the γ-irradiation in vacuo of nylon 6 film in the presence of aqueous acrylic acid and different concentrations of cupric chloride, the following relationships have been obtained: R_H ∝ [CuCl₂]^?1.0 and R_G ∝ [CuCl₂]^?0.3 Here [CuCl₂] is the concentration of cupric chloride in the bulk solution, and R_H and R_G denote the initial rates of homopolymerization and grafting, respectively. The values of ?1.0 and ?0.3 for the exponents indicate that the cupric ion is a less effective chain terminator in the film on account of its lower concentration there. Analyses of films grafted in different media demonstrate the copper content of a film to be independent of both the concentration of monomer in the solution and the degree of swelling. The copper content is primarily a function of the total poly(acrylic acid) present, i.e., (grafted species plus occluded homopolymer). Thus, at high doses, where the total poly(acrylic acid) associated with a film is significant, the grafting curves exhibit a falling off, and complex formation between cupric ion and a growing chain is considered a likely contributory factor.     

Vacuum UV photo-oxidation of polystyrene

Polystyrene (PS) was treated with vacuum UV (VUV) (λ = 104.8 and 106.7 nm) photo-oxidation and X-ray photoelectron spectroscopy detected a controlled increase in the atomic percentage of oxygen up to a saturation level of ca. 20 at% O. Initially, C–O and carbonyl groups are observed due to the formation of alcohols, ethers, esters, and ketones. Water contact angle measurements showed ca. 25% increase in hydrophilicity of the surface with oxidation. Atomic Force Microscopy observed little changes in surface roughness with treatment time. The super water absorbent polymer poly(acrylic acid) was thinly grafted to the modified PS surface.     

Improving the colour fastness of dyed nylon‐6 fabric by graft copolymerisation and curing of acrylic acid

The influence of grafting and grafting–curing of acrylic acid on the colour fastness of nylon‐6 fabric dyed with an acid dye of low wash fastness was investigated. The variables involved in grafting were initially optimised for pristine nylon‐6 fabric prior to grafting the same monomer onto the dyed fabrics. The highest graft yield achieved for the pristine and dyed nylon‐6 fabrics was 44 and 14% respectively. Grey scale testing and colorimetric analysis revealed that the highest colour fastness and the smallest drop in colour strength belonged to the dyed–grafted–cured nylon‐6 fabric. The colour components were measured, and the total colour difference of each sample after five washing cycles was computed. The specific colour difference showed that the implementation of either grafting or grafting–curing processes will alter the reference colour of the dyed fabric. The tensile strength of the grafted and grafted–cured fabrics was respectively 2.7 and 6.3% lower than that of dyed nylon‐6.     

Studies on salts of amine‐containing polymers with benzoic acids. III. Poly(N,N‐dimethylaminoethyl methacrylate‐g‐polyethylene) with benzoic acids

Poly(N,N‐dimethylaminoethyl methacrylate) [poly(DMAEMA)] was grafted onto a commercial polyethylene film by means of γ‐irradiation, and the grafted films were reacted with various liquid‐crystal‐forming benzoic acids. When polymeric salts consisting only of poly(DMAEMA) and the benzoic acids were heated, dissociation of salts was observed, but with poly(DMAEMA) grafted onto polyethylene films, salt dissociation or crystallization of dissociated acids could be avoided, and interesting morphologies, including liquid‐crystal phases, were observed for the systems of benzoic acids–poly(DMAEMA‐g‐polyethylene). © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 972–978, 2000     

Modification of halloysite nanotubes with poly(styrene–butyl acrylate–acrylic acid) via in situ soap‐free graft polymerization

Halloysite nanotubes (HNTs) were grafted with poly(styrene–butyl acrylate–acrylic acid) (P‐SBA) via an in situ soap‐free emulsion polymerization. To introduce double bonds into the HNTs, N‐(β‐aminoethyl)‐γ‐aminopropyl trimethoxysilane was first used to modify the HNTs and render amino groups, and then, the double bonds were anchored through an amidation reaction between acryloyl chloride and amino groups. P‐SBA chains were grafted onto HNTs because of participating of double bonds in the copolymerization of styrene, butyl acrylate, and acrylic acid. Fourier transforms infrared spectroscopy, transmission electron microscopy, specific surface area measurements, and thermogravimetric analysis were used to characterize the HNTs grafted with P‐SBA. The results indicate that 25.21% of P‐SBA was grafted onto the outer walls of the HNTs and filled into the inner spaces of the HNTs. The modification dramatically decreased the surface area of the HNTs. The property study of the HNTs grafted with P‐SBA focused on the dispersion behavior in the biphase system. The results show that the grafted HNTs dispersed stably in the water/cyclohexane biphase system and were a potential emulsifier. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Graft copolymers from thiolated starch and vinyl monomers

Thiol starches of degree of substitution (D.S.) 0.005–0.162 were prepared by displacing starch tosyloxy groups with xanthate and treating the resulting xanthate esters with either sodium hydroxide or sodium borohydride. Acrylonitrile, styrene, acrylamide, acrylic acid, and dimethylaminoethyl methacrylate were grafted onto the thiol starches with hydrogen peroxide as initiator. The peroxide caused both grafting of monomer and coupling of thiol groups to disulfide. Treating graft copolymers with sodium borohydride regenerated thiol groups from disulfide groups so that the grafting sequence could be repeated. By regenerating the thiol groups and repeating the grafting steps, high add-on and high-frequency starch graft copolymers were prepared. During four grafting sequences, acrylonitrile reacted with D.S. 0.162 thiol starch to give graft copolymers that contained increasing amounts of polyacrylonitrile (46.0–66.5%). Grafting frequency increased from 183 to 71 anhydroglucose units (AGU)/graft, while molecular weights of the grafted chains ranged between 20,000 and 25,200. The final product was hydrolyzed with potassium hydroxide solution to a copolymer, which absorbed up to 400 ml water per gram. Styrene was grafted onto thiol starch to give products containing 34.4–69.5% polystyrene with 986–3520 AGU/graft and having molecular weights of grafted chains between 276,000 and 364,000. Graft copolymers containing 48.9% polyacrylamide, 21.2% poly(acrylic acid), and 77.7% poly(2-methacryloyloxyethyldimethylammonium acetate) were obtained under similar conditions.     

Complexation of samarium ion with poly(acrylic acid) grafted onto polyethylene by radiation-induced method

Acrylic acid was graft-polymerized onto polyethylene powder by preirradiation method. The grafted powder (PE-g-AA) rapidaly adsorbed Sm^3? ion in high efficiency. The poly(acrylic acid) grafted to the surface region of PE acted as an effective chelating site for the relatively large Sm ion. The complex formation constant of Sm ion with PE-g-AA was much larger than those of Sm ion with poly(acrylic acid) and propionic acid and of Cu²⁺ ion with PE-g-AA.     

Formation of coatings with tailored properties on polyperoxide-modified polymeric surfaces

Modification (peroxidation) of polymer surfaces, polypropylene, polyethylene, polyethylene terephthalate, nylon 6-6, poly(phenylene oxide), and ethylene–propylene copolymer were affected by the surface grafting of functional polyperoxides (FPPs) such as poly(5-tert-butylperoxy-5-methyl-1-hexene-3-yne-co-octylmethacrylate) (VEP-co-OMA), poly{N-[(tert-butylperoxy)-methyl]acrylamide-co-octyl methacrylate} (PO-co-OMA), and poly(tert-butylperoxy-methacrylate-co-octyl methacrylate) (PEst-co-OMA). The degree of surface modification was shown to be determined primarily by the structure of the polymer substrate. Using a peroxidized surface as an initiator of grafted copolymerization enabled the grafting of functional monomers (acrylic acid, acrylamide, 4-vinylpyridine, and hydroxyethyl methacrylate) and polysaccharides (heparin, dextran, etc.) and thereby imparted adhesive, antibacterial, haemocompatible properties to the polymer surface.     

Adiabatic compressibility of some amphoteric polyelectrolytes

The results of adiabatic compressibility measurements for two amphoteric polyelectrolytes, acrylic acid–4-vinyl-N-n-butylpyridinium bromide copolymer and methacrylic acid–4-vinyl-N-n-butylpyridinium bromide copolymer, and their completely neutralized potassium salts have been described. The two amphoteric polyelectrolytes are strongly acidic, and the strength of the acidic group has been increased by the presence of the neighboring basic group. The reduced viscosity for these polyampholytes is extremely low (～0.03–0.07 dl/g) which may be on account of the mutual interaction of acid and base groups making the polyelectrolyte chain highly coiled and compact. The apparent molal volume ΦV₂ and apparent molal compressibility ΦK₂ are concentration independent. Their potassium salts showed the lowest ΦV₂ and ΦK₂ values as the electrostriction is highest here; these values showed a slight increase in the presence of dilute KBr solution as the dissociation is somewhat reduced. However, in excess KBr solution, the acrylic acid-containing copolymer having comparatively more carboxyl groups (21.7%) behaves more or less similar to poly(acrylic acid), whereas the methacrylic acid-containing copolymer, with only 15.1% carboxyl groups, behaves closely to poly(4-vinyl-N-n-butylpyridinium bromide). These polyelectrolytes showed absorption in the 2700 to 3800 Å region in the presence of chloride, bromide, and iodide ions which are due to charge transfer complex formation between the halide ions and the polymer nucleus. The magnitude of extinction coefficient for these two polyampholytes is much less than that of poly(4-vinyl-N-n-butylpyridinium bromide). The limiting values of apparent molal volume, ΦV₂⁰, for acrylic acid- and methacrylic acid-containing copolymers are 183.9 and 184.6 cc/mole, respectively. These experimentally determined values fall short of 9.2 and 6.2 cc/mole compared to the calculated values (if there was no interaction between acid and base groups) which are definitely due to mutual interaction of acid and base groups in the polymer chain.     

Surface grafting of polyester fiber with chitosan and the antibacterial activity of pathogenic bacteria

Three polyesters—poly(ethylene terephthalate), poly(2‐methyl‐1,3‐propylene terephthalate‐co‐ethylene terephthalate), and poly(1,4‐cyclohexylene terephthalate‐co‐ethylene terephthalate)—were preirradiated with ⁶⁰Co‐γ‐rays. Then, acrylic acid and N‐vinylformamide were grafted to these irradiated fibers. Fibers grafted with N‐vinylformamide were further hydrolyzed with acid so that the amide groups would convert into amino groups, and they were treated with glutaraldehyde so that aldehyde groups would be introduced. Chitosan or chitooligosaccharide was then grafted to these fibers via either esterification or imine formation. Four pathogenic bacteria—methicillin‐resistant Staphylococcus aureus‐1 (MRSA), Staphylococcus aureus‐2, Escherichid coli, and Pseudomonas aeruginosa—were tested to determine the antibacterial activities of chitosan‐grafted and chitooligosaccharide‐grafted fibers. The results showed that grafting chitosan via imine formation could achieve a higher surface density for amino groups and give higher antibacterial activity to those four bacteria tested. The antibacterial activity for E. coli was the highest and that for MRSA was the lowest among the four bacteria tested. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2977–2983, 2002