A new route for the preparation of flexible skin–core poly(ethylene-co-acrylic acid)/polyaniline functional hybrids

Surface modification of polymeric films is a way to obtain final products with high performance for many specific and ad hoc tailored applications, e.g. in functional packaging, tissue engineering or (bio)sensing. The present work reports, for the first time, on the design and development of surface modified ethylene–acrylic acid copolymer (EAA) films with polyaniline (PANI), with the aim of inducing electrical conductivity and potentially enable the electronic control of a range of physical and chemical properties of the film surface, via a new “grafting from” approach. In particular, we demonstrate that PANI was successfully polymerized and covalently grafted onto flexible EAA substrates, previously activated. The final hybrid materials and the corresponding intermediates were fully characterized via FTIR, XPS, SEM–EDAX, mechanical and electrical tests. The mechanical properties of the films are not detrimentally affected by each treatment step, while a significant increase in electrical conductivity was achieved for the new hybrid materials.     

Properties of cation-exchange membranes prepared by radiation grafting of acrylic acid onto tetrafluoroethylene–ethylene copolymers

Some properties of the ion-exchange membranes prepared by simultaneous and preirradiation techniques of grafting of acrylic acid onto tetrafluoroethylene–ethylene copolymer films, including porous microfilters, have been studied. The water content, electric resistance, transport number, distribution of grafting, thermal and chemical stability, and mechanical characteristics of the membranes were determined as a function of the grafting degree. Graft polymerization proceeds from both surfaces of the polymer film into the polymeric matrix depth. Cation-exchange membranes prepared possess good electrochemical and mechanical properties, high thermal and chemical stability at grafting degrees from 30 to 50%, and can be successfully used in electrodialysis processes. © 1993 John Wiley & Sons, Inc.     

Coefficient of friction reduction of ethylene‐co‐acrylic acid film: Effects of grafted 12‐aminododecanamide and solvent exposure

The effect of covalently bound 12‐aminododecanamide on the surface coefficient of friction (COF) of ethylene–acrylic acid copolymer (EAA) films was investigated. The reaction involved grafting 12‐aminododecanoic acid to the inherent carboxylic acid groups on the film, followed by amidation of the grafted amino acid. Conversion of film carboxylic acid groups to primary amide groups was also conducted to compare the impact of direct surface amidation. Subsequent measurements showed that both surface amidation schemes reduced the kinetic COF from 0.30 to 0.15 ～ 0.18. Repetitive COF testing revealed that amide‐modified EAA films maintained low COF values that were independent of the number of COF test runs. However, control experiments showed that COF values also depended greatly on simply exposing film to the various reaction solvents, which increased surface roughness. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2242–2248, 2005     

聚四氟乙烯薄膜表面光接枝改性的ESCA研究

对紫外光接枝表面改性的聚四氟乙烯（ＰＴＦＥ）薄膜进行了Ｘ射线光电子能谱的研究。结果表明,ＰＴＦＥ表面在预光照阶段发生ＣＦ键的断裂,产生活性中心;在接枝反应阶段,ＰＴＦＥ表面的ＣＦ键继续受紫外光照射而发生断裂,氟原子脱落,从而接枝上丙烯酸单体     

聚硅氧烷改性苯丙乳液──Ⅰ共混改性

聚合物乳液的共混改性可以得到一些独特的性能，改性的效果取决于共混聚合物的相容性及其形态结构，也取决于共混乳液的稳定性。本文研究了聚硅氧烷改性苯丙乳液的稳定性，聚硅氧烷改性橡胶膜的形态结构、两相间相容性，及其对改性橡胶膜力学性能的影响。ＥＳＣＡ和ＳＥＭ结果表明改性橡胶膜中存在明显的相分离，聚硅氧烷在膜的表面富集；通过接枝共聚使苯丙乳液粒子中含有部分聚硅氧烷，或聚硅氧烷乳液粒子中含有部分苯丙共聚物，两者都能降低两相间的界面张力，改善两相间的相容性，从而明显提高改性橡胶膜的力学强度，但只有当聚硅氧烷分子链与苯丙分子链通过接枝和机械缠结，才能明显抑制有机硅分子链向膜的表面迁移。     

Synthesis and Characterization of Linear Low Density Polyethylene Grafted Glycerol Monolauric Acid Monoitaconic Acid Diester

A reactive type dripping agent, glycerol monolauric acid monoitaconic acid diester (GLID) was synthesized in our laboratory. Grafting-copolymerization of linear low density polyethylene (LLDPE) with GLID was carried out by using β-ray irradiation in air in a twin-screw extruder. FT-IR was used to characterize the formation of grafting copolymer and evaluate their degree of grafting. The effects of monomer concentration, reaction temperature and screw run speed on degree of grafting were studied systematically. Crystallization rates of grafted LLDPE were faster than that of plain LLDPE at a given crystallization temperature. The tensile properties and light transmission of blown films were determined. Comparing with neat LLDPE film, no obvious changes could be found for the tensile strength, elongation at break and right angle tearing strength of LLDPE-g-GLID film. Acceleration dripping property of film samples was investigated. The dripping duration of LLDPE-g-GLID film and commercial antifog dripping film at 60° C were 69 days and 17 days, respectively.     

Electron-beam irradiation-induced grafting of acrylonitrile onto polyethylene

Low- and high-density polyethylene (PE) films were grafted with acrylonitrile (AN) by electron beam prior to irradiation. The distribution of graft chains over the cross section of the sample film was analyzed in terms of the distribution of nitrogen atoms contained in the AN by means of an electron probe microanalyzer (EPMA), and graft sites were studied in relation to the effect of grafting temperature on the percent graft and the oxygen permeability of the sample films. It was found that diffusion of AN into the film was the rate-limiting step in the grafting process, thus restricting the grafting to the surface of the film in the initial grafting stages. However, the grafting shifted to the center of film as the graft process proceeded, until a uniform distribution of graft chains was observed across the entire film thickness. High-density polyethylene (HDPE) was found to display a higher percent graft than did low-density polyethylene (LDPE), and percent graft tended to increase with increasing grafting temperature. On the other hand, film oxygen permeability decreased with increasing percent graft, but this decreasing trend decreased with increasing percent graft. These findings suggest that the grafting is initiated by radicals trapped in the amorphous phase near the crystalline regions and at the surface of crystallites and that graft chains grow toward the amorphous regions. As for the radicals contributing to graft polymerization, it appears that AN permeates deeper near the crystalline surface and that graft chains grow from these sites.     

Surface grafting polymerization of vinyl monomers on poly(tetrafluoroethylene) films by plasma treatment

Poly(tetrafluoroethylene) films were surface modified by argon plasma treatment followed by graft polymerization. Peroxidе groups were introduced on the surface of poly(tetrafluoroethylene) films after plasma treatment and the consequent contact with air when the films were taken out of the reactor. Grafting polymerization initiated by the surface peroxide (hydroxide) groups was performed on the poly(tetrafluoroethylene) film surface by using acrylic acid, 4-vinylpyridine and 1-vinylimidazole as monomers. Copolymers were obtained with grafting yield from 0.436 to 0.457 mg/cm² for poly(acrylic acid), from 0.299 to 0.390 mg/cm² for poly(4-vinylpyridine) and from 0.212 to 0.256 mg/cm² for poly(1-vinylimidazole), respectively. The free surface energies of the copolymers were determined. The chemical structures and the copolymer surfaces were characterized by IR, XPS and SEM analyses. High energy resolution X-ray photoelectron spectroscopy (XPS) confirmed the grafting of acrylic acid, 4-vinylpyridine and 1-vinylimidazole. The surface hydrophilicities of modified polytetrafluoroethylene films were significantly enhanced after plasma treatment and grafting modification. It is worth emphasizing that in this work acrylic acid, 4-vinylpyridine and 1-vinylimidazole were used as the reactive monomers for grafting on the poly(tetrafluoroethylene) film by plasma treatment. We believe that this vinyl monomers may be employable as functional groups, permitting a potentially wide range of applications: as ionomers, membranes, carriers for immobilization of biomolecules, for complex formation with heavy metals as catalysts.     

Photografting of acrylamide on ethylene–vinyl alcohol copolymer film

Photografting (λ > 300nm) of acrylamide on ethylene-vinyl alcohol copolymer film (vinyl alcohol unit = 56 mol%, film thickness = 20μm) was investigated at 60°C in water medium, where photoinitiators were coated on the film earlier. The percent grafting decreased in the order of xanthone ≈ benzophenone > anthraquinone > benzoyl peroxide. The graft efficiencies in each sensitized system were less than 30%, showing a predominant formation of homopolymer. Grafting of acrylamide on the film was also initiated in systems with and without photoirradiation when ceric salt was used as an initiator. Based on electron probe microanalysis of the grafted films, the grafted chains of the sample prepared by photografting were distributed inside the film, while those of the sample prepared by ceric salt-initiated grafting without photoirradiation were located mainly on the film surface. The grafted films prepared by the former system exhibited a higher moisture permeability than those prepared by the latter system.     

Modification of industrial polypropylene film by grafting of poly(acrylic acid)

Grafting of poly(acrylic acid) onto commercial polypropylene films following irradiation by γ-rays was carried out in order to improve their surface properties. The amount of grafting with the irradiation dose was found not to follow the expected linear dependence as it is normally observed for polypropylene films prepared in laboratory amounts. We therefore analyzed the influence of the industrial manufacture process in terms of orientation of the film and addition of antioxidants by determining the peroxide surface density and the extent of grafting therefrom. The unoriented polypropylene film presented the highest peroxide concentration and was thus the most adapated material for successful grafting. Whereas phenol antioxidants limit the peroxide formation and thus must be removed from the film for grafting, the thickness of the chemical modification and can be controlled by means of phosphites. Atomicforce microscopy and wettability measurements showed that the grafted poly(acrylic acid) was heterogeneously distributed on the surface of the film, explaining the observed low reproducibility of the grafting reaction. However, we observed that the polarity of the surface was increased by the grafting. © 1995 John Wiley & Sons, Inc.     

Tailoring bulk and surface grafting of poly(acrylic acid) in electron-irradiated PVDF

Endowing conventional hydrophobic poly(vinylidene fluoride) (PVDF) films with hydrophilic properties was conducted using electron beam irradiation. Grafting of acrylic acid (AA) in/onto pre-irradiated PVDF films was investigated. Reaction parameters, monomer concentration and inhibitor concentration were examined. Radiation grafted films (PVDF-g-PAA) were synthesized with various grafting yields ranging from 12 to 130 wt % in presence of Mohr's salt (25 wt %). Below 80 wt % of monomer concentration, the degree of swelling was found to increase with the grafting yield. The PAA was arranged randomly in all PVDF matrix (grafting through). Above 80 wt % of monomer concentration, the PAA was grafted only onto the surface of PVDF films leading to a highly dense layer of PAA. Grafting through or surface grafting processes were achieved by varying the water fraction in the initial monomer solution. Water molecule acts not only as a carrier for the monomer but also as a plasticizer expanding the film in the three dimensions. Evidences of grafting through and surface grafting were produced using FTIR in ATR mode, SEM coupled to X-ray detection and XPS. An accurate quantification of AA units was possible up to the micromole via a Cu²⁺–EDTA complex analyzed by UV–vis spectroscopy.     

Graft copolymer–lanthanide complexes obtained by radiation grafting on polyethylene film

Radiation‐induced grafting of acrylic acid (AAc) onto polyethylene (PE) film was investigated. The grafted films rapidly adsorbed Eu, Gd, Tb, and Dy ions at high efficiency. The carboxylic acid groups on the AAc‐grafted PE film acted as a chelating site for the selected lanthanide ions. Complex formation of lanthanide ions and the carboxylic acid group on PE film was investigated by IR, FT–Raman, and X‐ray photoelectron spectroscopy (XPS). Photoluminescence (PL) spectra and the thermal properties of the graft copolymer–lanthanide complexes onto PE film were also investigated. The application of such prepared graft copolymer–lanthanide complexes in the field of fluorescence emission displays (FEDs) may be interest. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 328–336, 2003     

A study on cytocompatible poly(chitosan-g-l-lactic acid)

A novel cytocompatible graft copolymer of chitosan and l-lactic acid (CL) was prepared by grafting l-lactic acid onto the amino groups in chitosan without a catalyst. The structures of the CL graft copolymers were characterized by FTIR, ¹³C-NMR and X-ray measurements. Degree of substitution and side-chain length were evaluated from salicylaldehyde and elemental analysis. The tensile strength and water uptake of the CL copolymers films were investigated as a function of feed ratio of LA/CS. The influence of pH on the swelling behavior of the copolymer films was determined and interpreted. Fibroblast culture was performed to evaluate cell proliferation on the copolymers films. The results showed that the cell growth rate on the copolymers films is faster than chitosan obviously.     

Synthesis of acrylic acid grafted silicone rubber via preirradiation graft copolymerization and its physical and dielectric properties

The hydrophilic monomer, acrylic acid (AA), has been grafted onto hydrophobic silicone rubber (SR) film via the γ-ray preirradiation graft technique. The AA percent graft in SR-g-AA film increases with increasing irradiation dose rate. The iron powder in monomer solution serves as one source of ferrous ion that is generated by the oxidation reaction with water. The swelling effect shows that the amount of chloroform taken up by an SR-g-AA membrane decreases with the increasing AA grafting, and the amount of water, alcohol, and glycerol taken up by an SR-g-AA film increases with increasing AA percent grafting. The contact angle, ultimate stress, and elongation at break of SR and SR-g-AA copolymers decrease with increasing AA percent grafting. The oxygen/nitrogen selectivity in these films can be enhanced by the graft modification. The thermal behaviors of SR-g-AA copolymers show the characteristics of SR and polyacrylic acid. Finally, the dielectric properties show that the SR-g-AA film has a superior dielectric property than the original SR and poly(AA) matrix. © 1996 John Wiley & Sons, Inc.     

Effect of an allyl pretreatment of starch on the grafting efficiency and properties of allyl starch‐g‐poly(acrylic acid)

Starch was pretreated with allyl etherification to enhance the grafting efficiency of the copolymerization of granular starch with acrylic acid and to improve the properties of starch‐g‐poly(acrylic acid) used as a warp sizing agent. The graft copolymerization was carried out in an aqueous dispersion with ferrous ammonium sulfate and hydrogen peroxide as initiators. Through the introduction of allyl groups into starch before the copolymerization, the grafting efficiency could evidently be enhanced, and properties such as fiber adhesion and film behaviors of the copolymer were improved. The pretreatment was capable of enhancing the grafting efficiency by about 10–20% when the degree of substitution of allyl starch ranged from 0.011 to 0.037. The adhesion and film behaviors also depended on the modification extent of the starch pretreatment and on the grafting ratio of the copolymer. The adhesion reached a maximum at a degree of substitution of 0.025, and the film behaviors were best when the degree of substitution ranged from 0.011 to 0.025. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Structural characterization of alpha methyl styrene‐butyl acrylate‐grafted polyetheretherketone films

Radiation‐induced graft copolymerization of alpha methyl styrene (AMS)‐butyl acrylate (BA) mixture onto poly(etheretherketone) (PEEK) was carried out to develop films of varying copolymer compositions. The characterization of films was carried out with fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), X‐ray diffraction analysis (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The presence of AMS and BA units within the film matrix was confirmed by FTIR. The intensity of the characteristic peaks for AMS and BA increased with the increasing grafted component in the films. The crystallinity of the films as observed from DSC and XRD decreased with the increasing graft levels. On the other hand, the melting temperature of the base polymer was almost unaffected by irradiation and the grafting process. The glass transition temperature (T_g) of the grafted film increased as compared to the virgin PEEK. Ungrafted film showed a stable thermogram up to ～500°C. However, the grafting introduced a new decomposition range in the copolymer, due to the presence of the AMS/BA. AFM images showed the formation of domains on the grafted PEEK film surface. The SEM also showed domain formation of the grafted component within the PEEK matrix. However, the fracture analysis did not show any prominent phase separation. Mechanical characterization of films in terms of tensile strength, elongation, and modulus was also carried out. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Proton‐exchange membranes via the grafting of styrene and acrylic acid onto fluorinated ethylene propylene copolymer by a preirradiation technique. IV. Dynamic mechanical analysis,X‐ray diffraction,and scanning electron microscopy studies of grafted and sulfonated membranes

The grafting of styrene and acrylic acid onto fluorinated ethylene propylene copolymer was carried out by a preirradiation technique. The resulting membranes were sulfonated with concentrated sulfuric acid. The effects of the degree of grafting and sulfonation on the structure of the membranes were studied by X‐ray diffraction and scanning electron microscopy. The crystallinity percentage decreased with increasing grafting. Scanning electron microscopy studies confirmed that grafting took place by a front mechanism, by which grafting started at the surface and slowly proceeded inwards. The dynamic mechanical properties of the membranes and their sulfonated derivatives were also investigated. The storage modulus at room temperature increased with grafting and increased further with sulfonation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1426–1431, 2005     

Study on radiation grafting of acrylic acid onto fluorine-containing polymers. II. Properties of membrane obtained by preirradiation grafting onto poly(tetrafluoroethylene)

Some properties of the membranes obtained by the preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene) (PTFE) film have been studied. The dimensional change by grafting and swelling, water uptake, electric conductivity, and mechanical properties of the grafted PTFE films were measured and were found to increase as the grafting proceeds. These properties were found to be dependent mainly on the degree of grafting regardless of grafting conditions except higher monomer concentration (80 wt %). The electric conductivity and mechanical properties of the membranes at 80 wt % monomer concentration is lower than those at a lower monomer concentration. The results suggest that the membranes obtained at 80-wt % acrylic acid solution have a somewhat heterogeneous distribution of electrolyte groups as compared with those prepared at a monomer concentration less than 60 wt %. X-ray microscopy of the grafted films revealed that the grafting begins at the part close to the film surface and proceeds into the center with progressive diffusion of monomer to give finally the homogeneous distribution of electrolyte groups. The membranes show good electrochemical and mechanical properties which make them acceptable for the practical uses as cation exchange membrane.     

Photoinduced graft copolymerization of nylon 6 fibers with acrylamide. II. Characterization and evaluation of properties

Nylon 6-g-polyacrylamide graft copolymer prepared by photoinduced initiation was characterized and some of its properties were evaluated. Intrinsic viscosity of the graft copolymer increased continously with percent grafting. Thermal stability decreased corresponding to the increase in add-on %. The moisture regain, diameter, and density showed an increase with percent grafting. The acid dyeability of the graft copolymer decreased with increase in graft level, whereas the disperse dye uptake increased initially up to a graft add-on of 28.9% and then showed a decrease.     

Surface and interfacial FTIR spectroscopic studies of latexes. IV. The effect of surfactant structure on the copolymer–surfactant interactions

The interactions between sodium dodecylbenzene sulfonate (SDBS) and the components of an ethyl acrylate/methacrylic acid (EA/MAA) copolymer latex were examined and the influences of using D₂O as the synthetic suspension medium were investigated. Whereas it is found that D₂O has no detectable influence on the fully coalesced latex films, the film coalescence conditions are shown to significantly affect the nature of surfactant interactions within the film matrix. When films are prepared and stored under controllable low atmospheric water-vapor concentrations, hydrogen-bonding interactions between the surfactant SO₃^?Na⁺ groups and the copolymer acid functionality dominate. However, coalescence and storage of the films under higher relative humidity conditions results in a displacement of these interactions in favor of the hydrated form of the surfactant. It is also shown that the presence of an aromatic ring adjacent to the surfactant sulfonate group exerts an influence on the nature of the SO₃^? ··· HOOC interactions within the copolymer matrix. Relative to sodium dioctyl sulfosuccinate (SDOSS), the aromatic group near hydrophilic end of SDBS increases the strength of the S? O bond in the presence of acid interactions. © 1993 John Wiley & Sons, Inc.