As Acrylamide Research Articles

Surface modification of poly(tetrafluoroethylene) films by low energy Ar + ion-beam activation and UV-induced graft copolymerization

Surface modification of poly(tetrafluoroethylene) (PTFE) films by Ar + ion-beam irradiation with varying ion energy and ion dose was carried out. The changes in surface composition of the irradiated PTFE films were characterized, both in situ and after exposure to air, by X-ray photoelectron spectroscopy (XPS). The possible mechanisms of chemical reaction induced by the incident ion beam on the surface of PTFE film included defluorination, chain scission and cross-linking, as indicated by the presence of the characteristic peak components associated with the CF 3,CF, and C(CF 2) 4 species in the C 1s core-level spectra, the decrease in surface [F]/[C] ratio, and the increase in surface micro-hardness of the Ar + ion-beam-treated PTFE films. Furthermore, the free radicals generated by the ion-beam could react with oxygen in the air to give rise to oxidized carbon species, such as the peroxides, on the PTFE surface. Thus, after exposure to air, the Ar + ion-beam-pretreated PTFE films were susceptible to further surface modification by UV-induced graft copolymerization with a vinyl monomer, such as acrylamide (AAm). The graft concentrations were deduced from the XPS-derived surface stoichiometries. The Ar + ion energy and the ion dose affected not only the surface composition of the treated films but also the graft copolymerization efficiency of the corresponding pretreated films.

Functionalizing of polyurethane surfaces by photografting with hydrophilic monomers

Poly(ester urethane) (PU) with functional groups (amide, hydroxyl, carboxyl) on surfaces were prepared by grafting monomers such as acrylamide (AAm), hydroxyethyl acrylate (HEA), and methacrylic acid (MAA) onto the PU membranes. Grafting copolymerization was carried out by the combined use of photooxidization and UV irradiation grafting. The PU membrane was photooxidized in hydrogen peroxide solution under UV light to yield hydroperoxide groups on the surface and then irradiation grafting with monomer in water. The ATR-FTIR spectrum, X-ray photoelectron spectroscopy characterized the grafted copolymers and verified the occurrence of grafting copolymerization. The results showed that the content of hydroperoxide groups yielded was dependent on the photooxidization time and reached maximum at about 8 h. Grafting copolymerization was enhanced when irradiating by UV light. The degree of grafting was increased with the increase of content of hydroperoxide groups, irradiation time, and monomer concentration. The grafting copolymerization was enhanced when an appropriate amount of ferrous ions was added. After grafting, the wettability of PU and the water absorption percentage increased with the degree of grafting. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2505–2512, 2000

In Situ Observation of Dithiocarbamate-Based Surface Photograft Copolymerization Using Quartz Crystal Microbalance

A quartz crystal microbalance (QCM) technique which can detect weight increase in the nanogram order has been employed to continuously monitor the iniferter-based surface photograft polymerization behavior of vinyl monomers. The gold electrodes of the QCM were thinly coated with a photoreactive polystyrene partially derivatized with N,N-diethyldithiocarbamylmethyl groups acting as iniferters. A monotonic decrease in the resonance frequency of the vibrating oscillator of QCM, which was correlated with the weight increase via graft copolymerization initiated on the polystyrene, occurred immediately after ultraviolet light irradiation of the coated electrode surface in a methanolic or aqueous solution of vinyl monomers such as acrylamide (AAm), N,N-dimethylacrylamide (DMAAm), methacrylamide (MAm), methacrylic acid (MA), ethyl acrylate (EA), 2-hydroxyethyl methacrylate (HEMA), 2-(dimethylamino)ethyl methacrylate (DMAEM), N-vinyl-2-pyrrolidone (VP), and styrene (ST), except for vinyl acetate (VA). Upon cessati...

Chemical Modification of Silicon (100) Surface via UV-Induced Graft Polymerization

Modification of argon plasma-pretreated single-crystal silicon wafer surface via UV-induced graft polymerization with various functional monomers, such as acrylamide (AAm), N,N‘-diamethylaminoethyl methacrylate (DMAEMA), and 2,2,2-trifluoroethyl acrylate (TFEA), was achieved. The modified Si(100) surfaces were characterized by X-ray photoelectron spectroscopy (XPS), imaging XPS, atomic force microscopy (AFM), and water contact angle measurements. The graft polymerization was affected by plasma pretreatment time and UV irradiation time. XPS results suggest that mild and brief plasma treatment is sufficient to cause surface oxidation and to generate sufficient peroxides and hydroxyl peroxides for the subsequent UV-induced graft polymerization in the presence of a vinyl monomer. Prolonged plasma treatment and the accompanying overoxidation of the silicon surface have an adverse effect on the graft polymerization. For all the cases investigated, the XPS results revealed that the grafted polymers form a thin l...

Radiation-Induced Graft Copolymerization Of Some Vinyl Monomers Onto Waste Rubber Powder

Rubber powder was subjected to graft copolymerization with different vinyl monomers such as acrylamide (AAm), acrylic acid (AAc), and acrylonitrile (AN). Graft copolymerization of these monomers onto rubber powder was carried out using gamma radiation. The effects of different parameters such as monomer concentration, radiation dose, inhibitor concentration, and type of reaction solvent on the graft yield were studied. It was found that the maximum graft yield obtained is 90%, 24%, and 42% for AAc, AAm, and AN, respectively. The grafted rubber powder obtained was tested as ion exchanger for copper and lead, and its capacity for ion recovery was found to be dependent on the type of monomer and graft yield. For instance, polyacrylamide and sodium salt of polyacrylic acid grafted onto rubber powder are more efficient as ion exchangers for both copper and lead ions than polyacrylonitrile. Amidoxime derivative of polyaerylonitrile is more efficient as ion exchanger than the parent polyaerylonitrile.

Surface modification of polyimide films by graft copolymerization

AbstractSurface modifications of polyimide (PI) films by Ar‐plasma, O2‐plasma, and O3 pretreatment and by near‐UV light‐induced graft copolymerization with water‐soluable monomers, such as acrylamide (AAm), acrylic acid (AAc), and sodium salt of 4‐styrenesulfonic acid (NaSS), have been carried out. The angle‐resolved x‐ray photoelectron spectroscopy (XPS) results show that surface pretreatment results in the formation of peroxide species on the polymer film surfaces and leads to a substantial enhancement of the density of surface graft. The XPS results further suggest that in the case where substantial grafting has taken place, the grafted polymer either forms a surface layer uniformly intermixed with the substrate chains, or a graft‐rich surface layer in the case of sterically hindered migration of the graft. The resulting surface structures are further supported by dynamic water contact angle measurements. These surface structures are probably associated with the thermoset character of PI, as they differ from the stratified microstructures observed on most thermoplastic films after surface modification by graft copolymerization with hydrophilic monomers. © 1995 John Wiley & Sons, Inc.

Near-u.v. radiation induced surface graft copolymerization of some O 3-pretreated conventional polymer films

Pristine and O 3-pretreated polymer films of polyethylene terephthalate, low-density polyethylene, high-density polyethylene, polystyrene, polypropylene and polycarbonate have been subjected to near-u.v. radiation induced graft copolymerization with water-soluble monomers such as acrylamide (AAm), acrylic acid (AAc) and sodium salt of 4-styrenesulfonic acid (NaSS). The AAc and NaSS grafted substrates are also coated with polyaniline (emeraldine base) to give rise to self-protonated electroactive surfaces. Using angle-resolved X-ray photoelectron spectroscopy the physical and chemical structures of each copolymerized surface and interface are investigated. The results show that, in each case, O 3 pretreatment leads to substantial enhancement of the density of graft and much improved hydrophilicity for the grafted substrates. The increase in graft density also brings about a higher extent of protonation of the coated emeraldine base. The graft polymer is shown to penetrate or partially penetrate the substrate polymer resulting in a thin surface layer which is richer in the substrate polymer. This surface morphology is in agreement with the data obtained using static secondary ion mass spectrometry.

Dependence of water sorption-desorption characteristics of N,N?-methylene-bis-acrylamide and tetraethyleneglycol diacrylate-crosslinked polyacrylamides on crosslinking

Hydrophilic monomers such as acrylamide (AA) when crosslinked with highly hydrophilic flexible tetraethyleneglycol diacrylate (TEGDA) and N,N′-methylene-bis-acrylamide (NNMBA) of intermediate polarity and hydrophilicity provides highly water swellable hydrogels. These water-swellable but water insoluble macromolecules possess a number of physicochemical properties useful for applications in biomedical and other technological fields. This paper describes the swelling/deswelling characteristics and the ability for water retention of these polymers in different compositions. Water sorption in these crosslinked polyacrylamides is dependent on a number of variables of polymer synthesis.

X-ray photoelectron spectroscopy and secondary ion mass spectrometry studies of some surface modified hydrocarbon films

Near-ultraviolet light induced graft copolymerization of water soluble monomers such as acrylamide (AAm), acrylic acid (AAc), and sodium salt of 4-styrenesulfonic acid (NaSS) onto pristine and ozone-pretreated polyethylene terephthalate (PET), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polystyrene (PS), polypropylene (PP), and polycarbonate (PC) had been carried out. An emeraldine (EM) base was then coated onto the AAc and NaSS polymer grafted substrates to give rise to self-protonated conductive surfaces. Using x-ray photoelectron spectroscopy and secondary ion mass spectrometry techniques, it was found that ozone pretreatment led to a substantial enhancement of the density of graft, and subsequently, the extent of protonation of the EM base on these polymer substrates. The models describing the graft structure or morphology are also presented.

Phenyl‐2,4,6‐trimethylbenzoylphosphinates as water‐soluble photoinitiators. Generation and reactivity of OṖ(C6H5)(O−) radical anions

AbstractLithium‐ and magnesium phenyl‐2,4,6‐trimethylbenzoylphosphinates (TMPPL and TMPPM) are effective water‐soluble photoinitiators for the free‐radical polymerization of appropriate monomers such as acrylamide (AA) and methacrylamide (MAA) in aqueous solution. They are also capable of initiating the polymerization of other olefinic compounds such as styrene (St), methyl methacrylate (MMA) or acrylonitrile (AN) in water‐containing solvent mixtures such as 1:1 water‐acetonitrile mixtures. This is due to the fact that TMPPL and TMPPM undergo α‐scission with a rather high quantum yield (ϕ(α) ≈ 0,35) resulting in the formation of 2,4,6‐trimethylbenzoyl radicals and OṖ (C6H5)(O−) radical anions. The latter are very reactive toward olefinic monomers. Bimolecular rate constants kR+M/(L/(mol · s)) were determined by flash photolysis at room temperature, e. g. in neat water: 3,8 · 108 (MAA), 2,2 · 108 (AA), and in H2O/CH3CN (1:1, v/v): 1,8 · 107 (St), 1,2 · 108 (MMA), 8,4 · 107 (AN).