Surface grafting of polymers onto glass plate: Polymerization of vinyl monomers initiated by initiating groups introduced onto the surface

The surface grafting of polymers onto a glass plate surface was achieved by the polymerization of vinyl monomers initiated by initiating groups introduced onto the surface. Azo groups were introduced onto the glass plate surface by the reaction of 4,4′-azobis(4-cyanopentanoic acid) with isocyanate groups, which were introduced by the treatment with tolylene-2,4-diisocyanate. The radical polymerization of various vinyl monomers was initiated by azo groups introduced onto the glass plate surface and the corresponding polymers were grafted from the surface: The surface grafting of polymers was confirmed by IR spectra, and the contact angle of surface, with water. The contact angle of the glass plate increased by the grafting of hydrophobic polymers, but decreased by the grafting of hydrophilic polymers. The radical postpolymerization was successfully initiated by the pendant peroxycarbonate groups of grafted polymer on the surface to give branched polymer-grafted glass plate. The cationic polymerization of vinyl monomers was also successfully initiated by benzylium perchlorate groups introduced onto the glass plate surface and the corresponding polymers were grafted onto the surface. The contact angle of the glass plate surface obtained from the cationic polymerization of styrene was larger than that obtained from the radical polymerization. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2165–2172, 1997     

Surface grafting of polymer onto carbon thin film

The surface grafting of polymers onto carbon thin film deposited on a glass plate was achieved by two methods: the graft polymerization initiated by initiating groups introduced onto the surface; and the trapping of polymer radicals by surface aromatic rings of the thin film. It was found that the radical and cationic graft polymerization of vinyl monomers are initiated by azo and acylium perchlorate groups introduced onto the surface, respectively, and the corresponding polymers are grafted onto the surface: the surface grafting of polymers were confirmed by the contact angle of the surface with water. In addition, the anionic ring-opening alternating copolymerization of epoxides with cyclic acid anhydrides was found to be initiated by potassium carboxylate groups on the carbon thin film to give the corresponding polyester-grafted carbon thin film. On the other hand, polymer radicals formed by the decomposition of azo polymer, such as poly(polydimethylsiloxane-azobiscyanopentanoate) and poly(polyoxyethylene-azobiscyanopentanoate), were successfully trapped by the surface aromatic rings of carbon thin film and polydimethylsiloxane and polyoxyethylene were grafted onto the surface. © 1995 John Wiley & Sons, Inc.     

Surface grafting of polymers onto aramid powder: graft polymerization of vinyl monomers initiated by azo groups introduced onto the surface of aramid powder

The radical graft polymerization of vinyl monomers onto the surface of aramid powder, i.e., poly(p-phenylene terephthalamide) powder, initiated by azo groups introduced onto the surface was investigated. The introduction of azo groups onto the aramid surface was achieved by the reaction of surface acyl chloride groups, which were introduced by the treatment of aramid powder with adipoyl dichloride, with 2,2′-azobis[2-(2-imidazolyn-2-yl)propane] in the presence of pyridine: the amount of azo groups thus introduced onto the surface was determined to be 0.57 mmol/g by elemental analysis. It was found that the polymerizations of methyl methacrylate (MMA) and styrene were successfully initiated by the azo groups on the surface and that the corresponding polymers were grafted onto the surface. The percentage of surface grafting of polystyrene and poly(methyl methacrylate) (PMMA) increased up to 37.6 and 26.5%, respectively. Thermogravimetric analysis of polymer surface-grafted aramid powder confirmed that the grafting of polymers is limited on the surface. The polymerization rate was found to bear a first-order dependence on the concentration of aramid powder having azo groups. This suggests that in graft polymerization, unimolecular termination preferentially proceeds.     

Cationic graft polymerization of polymers from carbon fiber initiated by acylium perchlorate groups introduced onto the surface

The cationic graft polymerization of several monomers initiated by acylium perchlorate groups introduced onto the carbon fiber surface was investigated to modify the surface. The introduction of acylium perchlorate groups was successfully achieved by the reaction of silver perchlorate with acyl chloride groups, which were introduced by the reaction of surface carboxyl groups with thionyl chloride. It was found that the cationic polymerization of styrene is initiated by acylium perchlorate groups on the carbon fiber. In the polymerization, polystyrene was grafted onto the carbon fiber surface through the propagation of polystyrene from the surface. Ungrafted polymer was also formed by the chain transfer reaction of growing polymer cation to the monomer. The acylium perchlorate groups have the ability to initiate cationic ring-opening polymerization of tetrahydrofuran (THF) and ε-caprolactone (CL), polyTHF and polyCL being grafted onto the carbon fiber surface, respectively. Polyacetals, such as poly(1,3-dioxolane) and polyoxymethylene, were able to graft onto the carbon fiber by cationic ring-opening polymerization of the corresponding monomers.     

Grafting of water‐soluble sulfonated monomers onto functionalized fumed silica nanoparticles via surface‐initiated redox polymerization in aqueous medium

Sulfonated polymer/fumed silica hybrid nanoparticles were prepared via surface‐initiated free radical polymerization of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (PAMPS‐g‐FSN), styrene sulfonic acid sodium salt (PSSA‐g‐FSN) and vinyl sulfonic acid sodium salt (PVSA‐g‐FSN) from the surface of aminopropyl‐functionalized fumed silica nanoparticles (AFSNs) dispersed in aqueous medium. Cerium(IV) ammonium nitrate/nitric acid and sodium dodecyl sulfate were used as redox initiator and stabilizer respectively. AFSNs were prepared by covalently attaching 3‐aminopropyltriethoxysilane onto the surface of fumed silica nanoparticles. Sulfonated monomers (AMPS, SSA or VSA) were then grafted onto the AFSNs ultrasonically dispersed in water via redox initiation at 40 °C. Structure, thermal properties, particle size and morphology of the AFSNs and PAMPS‐g‐FSN, PSSA‐g‐FSN and PVSA‐g‐FSN hybrid nanoparticles were characterized by Fourier transform infrared spectroscopy, TGA, SEM, transmission electron microscopy (TEM) and dynamic light scattering (DLS). The results indicated that the sulfonated monomers were successfully grafted onto the fumed silica nanoparticles. Grafting amounts of the sulfonated polymers onto the fumed silica nanoparticle surface were estimated from TGA thermograms to be 59%, 13% and 29% for the PAMPS, PSSA and PVSA, respectively. From SEM, TEM and DLS analysis, polymer‐grafted fumed silica nanoparticles with an average diameter smaller than 70 nm and a (semi‐) spherical shape were observed. A significant bimodal particle size distribution was observed only for the PAMPS‐g‐FSN with average diameters of 39.6 nm (84.1% per number) and 106 nm (15.9% per number). The hydrophilic sulfonated polymer/grafted fumed silica obtained from the redox graft polymerization gave a stable colloidal dispersion in acidic aqueous medium. Copyright © 2012 Society of Chemical Industry     

Grafting of vinyl polymers onto VGCF surface and the electric properties of the polymer-grafted VGCF

The graft polymerization of vinyl monomers onto vapor grown carbon fibers (VGCF) initiated by the system consisting of molybdenum hexacarbonyl (Mo(CO)₆) and trichloroacetyl (COCCl₃) groups introduced onto the surface was investigated. The introduction of trichloroacetyl groups onto VGCF surface was successfully achieved by the reaction of carboxyl groups on VGCF surface with trichloroacetyl isocyanate. It was found that the radical graft polymerization of vinyl monomers, such as methyl methacrylate (MMA), styrene, and glycidyl methacrylate (GMA) is successfully initiated by the system consisting of Mo(CO)₆ and COCCl₃ groups introduced onto the surfaces. In the polymerization, the corresponding vinyl polymers were effectively grafted onto the VGCF surface, based on the propagation of polymer from surface radicals formed by the interaction of trichloroacetyl groups and Mo(CO)₆: the percentage of PMMA grafting reached 40%. Polymer-grafted VGCF gave a stable colloidal dispersion in good solvents for grafted polymer. The electric resistance of composite prepared from the polymer-grafted VGCF suddenly increased in organic solvent vapor over 10³ times, and returned to initial resistance when it was transferred into dry air. These results indicate that such composites can be used as novel gas sensors.     

Surface grafting of polymers onto ultrafine silica: Cationic polymerization initiated by oxoaminium perchlorate groups introduced onto ultrafine silica surface

Summary The cationic polymerization initiated by oxoaminium perchlorate groups introduced onto ultrafine silica surface was investigated. The oxoaminium perchlorate groups were successfully introduced by treatment of nitroxyl radicals on silica surface with perchloric acid. The introduction of the nitroxyl radicals was achieved by reaction of 4-hydroxy-2,2,6,6-tetramethyl-piperidinyloxy radical with acid anhydride groups on the surface. The cationic polymerization of isobutyl vinyl ether, N-vinylcarbazole, 2,3-dihydrofuran, and -butyrolactone was initiated by oxoaminium perchlorate groups introduced onto the surface and the corresponding polymers were grafted onto the surface through the propagation of grafted polymer chain from the surface oxoaminium perchlorate groups.     

Preparation and dispersibility of poly(L‐lactide)‐grafted silica nanoparticle

To improve dispersibility of silica nanoparticle in organic solvents, the grafting of poly(L ‐lactide) (PLLA) onto silica nanoparticle surface by ring‐opening polymerization of L‐lactide (LA) was investigated in the presence of an amidine base catalyst. The ring‐opening polymerization of LA successfully initiated in the presence of silica having amino groups (silica‐NH₂) and an amidine base catalyst to give PLLA‐grafted silica, but not in the presence of untreated silica (silica‐OH). In the absence of the amidine base catalyst no ring‐opening polymerization of LA even in the presence of silica‐NH₂ and no grafting of PLLA onto silica were observed. It became apparent that the amidine base catalyst acts as an effective catalyst for the ring‐opening graft polymerization of LA from the surface of silica‐NH₂. In addition, it was found that the percentage of PLLA grafting onto silica could be controlled according to the reaction conditions. The average particle size of PLLA‐grafted silica was smaller than that of silica‐NH₂. Therefore, it was considered that the aggregation structure of silica nanoparticles was considerably destroyed by grafting of PLLA onto the surface. The PLLA‐grafted silica gave a stable dispersion in polar solvents, which are good solvents for PLLA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Graft copolymerization of thiophene onto polystyrene synthesized via nitroxide‐mediated polymerization and its polymer − clay nanocomposite

A new strategy for graft copolymerization of thiophene onto a polystyrene (PSt) backbone by a multi‐step process is suggested and the effects of an organoclay on the final properties of the graft copolymer sample are described. For this purpose, first poly(styrene‐co‐4‐chloromethyl styrene) [P(St‐co‐CMSt)] was synthesized via nitroxide‐mediated polymerization. Afterwards, the chlorine groups of P(St‐co‐CMSt) were converted to thiophene groups using the Kumada cross‐coupling reaction and thiophene‐functionalized PSt multicenter macromonomer (ThPStM) was synthesized. The graft copolymerization of thiophene monomers onto PSt was initiated by oxidized thiophene groups in the PSt chains after addition of ferric chloride (FeCl₃), an oxidative catalyst for polythiophene synthesis, and FeCl₃‐doped polythiophene was chemically grafted onto PSt chains via oxidation polymerization. The graft copolymer obtained was characterized by ¹H NMR and Fourier transform infrared spectroscopy, and its electroactivity behavior was verified under cyclic voltammetric conditions. Finally, PSt‐g‐PTh/montmorillonite nanocomposite was prepared by a solution intercalation method. The level of dispersion of organoclay and the microstructure of the resulting nanocomposite were probed by means of XRD and transmission electron microscopy. It was found that the addition of only a small amount of organoclay (5 wt%) was enough to improve the thermal stabilities of the nanocomposite.© 2013 Society of Chemical Industry     

Surface grafting of polymers onto ultrafine silica: cationic polymerization initiated by benzylium perchlorate groups introduced onto ultrafine silica surface

Summary The cationic graft polymerization initiated by benzylium perchlorate groups introduced onto ultrafine silica surface was investigated. The introduction of benzylium perchlorate groups onto the surface was achieved by the reaction of silver perchlorate with surface benzyl chloride groups, which were introduced by the treatment of silica with 4-(chloromethyl)phenyltrimethoxysilane. The cationic graft polymerization of styrene and cationic ring-opening polymerization of -caprolactone were found to be initiated by the surface benzylium perchlorate groups and the corresponding polymers were grafted onto the surface. The percentage of grafting onto silica surface decreased with increasing polymerization temperature, because chain transfer reaction of growing polymer cation is accelerated with increasing polymerization temperature.     

Graft polymerization of vinyl monomers from initiating groups introduced onto polymethylsiloxane-coated titanium dioxide modified with alcoholic hydroxyl groups

The grafting of vinyl polymers onto the surface of polymethylsiloxane-coated titanium dioxide modified with alcoholic hydroxyl groups (Ti/Si–R–OH) were investigated. The introduction of azo and trichloroacetyl groups onto the surface of Ti/Si–R–OH was achieved by the reaction of the surface alcoholic hydroxyl groups with 4,4′-azobis(4-cyanopentanoic acid) and trichloroacetyl isocyanate, respectively. The radical polymerizations of vinyl monomers were successfully initiated by the azo groups introduced onto the surface and by the system consisting of Mo(CO)₆ and Ti/Si–R–COCCl₃. During the polymerization, the corresponding polymers were effectively grafted onto the titanium dioxide surface through propagation from surface radicals formed by the decomposition of azo groups and by the reaction of Mo(CO)₆ with trichloroacetyl groups on the surface. The percentage of grafting and grafting efficiency in the graft polymerization initiated by the system consisting of Ti/Si–R–COCCl₃ and Mo(CO)₆ were much larger than those initiated by azo groups. The polymer-grafted titanium dioxide was found to produce a stable colloidal dispersion in good solvents for the grafted polymer. The dispersibility of poly(N,N-diethylacrylamide)-grafted titanium dioxide in water was controlled by temperature. In addition, the wettability of the surface of titanium dioxide to water was readily controlled by grafting of hydrophilic or hydrophobic polymers.     

Effect of initiating groups introduced onto ultrafine silica on the molecular weight polystyrene grafted onto the surface

Summary The effect of initiating groups introduced onto silica surface on the molecular weight of grafted polystyrene chain was investigated. By the treatment of polystyrene-grafted silica with aqueous solution of alkali, surface grafted polystyrene was isolated from the surface. The molecular weight of polystyrene grafted onto the silica obtained from the radical graft polymerization initiated by peroxyester groups introduced onto the surface was found to be much larger than that from the cationic polymerization initiated by acylium perchlorate groups. The number of grafted polystyrene in the radical polymerization, however, was much less than that in the cationic polymerization. Furthermore, the effect of molecular weight of grafted polystyrene on the dispersibility of silica in tetrahydrofuran was examined.     

Study on antithrombosis dialytic membrane prepared by preirradiation grafting

A new antithrombosis dialytic membrane with a hydrophilic–hydrophobic microphase structure was prepared by preirradiation grafting of β‐hydroxyethyl methacrylate (HEMA) and styrene (St) onto ethylene–vinyl acetate (EVA). The influence of some effects, such as preirradiation dose, dose rate, grafting reaction temperature, reaction time, and monomer component, on the degree of grafting was determined, and the properties of the grafted films were investigated. Compared with the conventional EVA‐grafted hydrophilic monomer, the EVA films grafted with HEMA and St have superior antithrombogenicity; the antithrombogenicity and permeability of EVA‐g‐(HEMA‐co‐St) were 30 and 20 times higher than those of the ungrafted films, respectively, when the volume ratio (HEMA versus St) was about 7:3. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1321–1327, 2000     

Functionalization of multi-walled carbon nanotubes by free radical graft polymerization initiated from photoinduced surface groups

An easy method for preparing polymer-grafted multi-walled carbon nanotubes (MWCNTs) with high graft yields was developed by using free radical graft polymerization (FRGP) from photoinduced surface initiating groups on MWCNTs. The surface initiating groups were first formed by UV irradiation of MWCNTs previously modified with 2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] (VA-086) (MWCNTs-OH) in the presence of benzophenone in benzene, and the subsequent FRGP of vinyl monomers was carried out consecutively at 80 °C. The surface initiating groups were homolytically cleaved to surface radicals and semipinacol radicals by thermal activation, and the surface radicals initiated FRGP. Polystyrene, poly(butyl acrylate), poly(methyl methacrylate), and poly(2-hydroxyethyl methacrylate) were successfully grafted onto the surface of MWCNTs with graft yields of 46, 26, 37, and 53 wt.%, respectively, after 15 h of FRGP.     

Grafting of branched polymers onto the surface of vapor grown carbon fiber and their electric properties

The grafting of branched polymers onto vapor grown carbon fiber (VGCF) surface and their electric properties of the composite prepared from the branched polymer-grafted VGCF were investigated. In the first step, the grafting of copolymers having pendant peroxy groups onto VGCF was achieved by the copolymerization of 1-(t-butylperoxy-i-propyl)-3-i-propenylbenzene (BPPB) with vinyl monomers initiated by the system consisting of Mo(CO)₆ and trichloroacetyl groups previously introduced onto the surface. In the second step, the postpolymerization of vinyl monomers was initiated by pendant peroxy groups of grafted poly(vinyl monomer-co-BPPB) on the surface to give branched vinyl polymer-grafted VGCF. The dispersibility of VGCF in THF was remarkably improved by grafting of branched polymers onto the surface. The electric resistance of composites prepared from the branched polymer-grafted VGCF suddenly increased when the composites were transferred into solvent vapors and suddenly decreased when they were transferred to dry air.     

Synthesis of polymer‐grafted natural rubbers by radical photopolymerization of vinyl monomers initiated from the rubber chains

The synthesis of polymer‐grafted natural rubbers (NRs) was considered through photopolymerization of vinyl monomers initiated from N,N‐diethyldithiocarbamate groups previously introduced onto cis 1,4‐polyisoprene units of NR chains. The development of the procedure was made with methyl methacrylate (MMA) as monomer. First, initiation of MMA photopolymerization was tested using a model molecule of the N,N‐diethyldithiocarbamate‐functionalized 1,4‐polyisoprene unit to verify the feasibility of the procedure considered. Then, MMA polymerization was successfully initiated from N,N‐diethyldithiocarbamate‐functionalized NR backbone used as macroinitiator, and the conditions of grafting were optimized. It was shown that MMA grafting could occur either in monomer medium, in solution in toluene, and in latex medium, and that the quantities of homopolymer formed were still low. Thereafter, grafting studies were performed with other vinyl monomers (styrene, methacrylonitrile, acrylamide, acrylic acid) showing that grafting efficiency depends essentially on the nature of the monomer. The method developed here was shown particularly well adapted for the synthesis of polymer‐grafted NR with monomers of low polarity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Alkali‐responsive membrane prepared by grafting dimethylaminoethyl methacrylate onto ethylene vinyl alcohol copolymer membrane

An alkali‐responsive membrane was prepared by grafting dimethylaminoethyl methacrylate (DMAEMA) onto ethylene vinyl alcohol copolymer (EVAL) membrane using ultraviolet (UV) irradiation graft polymerization. A subtranslucent state of EVAL membrane swelling in the DMAEMA solution was observed, and such a state enabled the passage of UV light through all the pores, inducing graft polymerization inside the pores and on the back. Attenuated total reflectance Fourier‐transform infrared spectrometer (ATR‐FTIR), X‐ray photoelectron spectroscopy (XPS), field‐emission scanning electron microscopy (FESEM), and energy‐dispersive X‐ray spectroscope (EDX) confirmed that the poly(DMAEMA)‐grafted chains existed not only on the top surface, but also inside the pores and on the back. Atomic force microscopy (AFM) and nitrogen adsorption analysis confirmed that the grafted chains collapsed in air, and decreased the surface roughness, surface area, and pore size of the grafted membranes. Alkali‐responsive properties of the poly(DMAEMA)‐grafted EVAL membrane (i.e., contact angle, permeability, and selectivity) were observed in the pH range of 9–10. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41775.     

Postgrafting of vinyl polymers onto hyperbranched poly(amidoamine)-grafted nano-sized silica surface

To prepare polymer-grafted nano-sized silica with hydrophilic core and hydrophobic shell and with higher percentage of grafting, the postgraft polymerization of vinyl polymers onto hyperbranched poly(amidoamine)-grafted (PAMAM-grafted) nano-sized silica initiated by the system consisting of Mo(CO)₆ and terminal trichloroacetyl groups of PAMAM-grafted silica was investigated. The introduction of trichloroacetyl groups onto PAMAM-grafted silica surfaces was readily achieved by the reaction of trichloroacetyl isocyanate with terminal amino groups of PAMAM-grafted silica. It was found that the polymerization of vinyl monomers, such as methyl methacrylate (MMA), styrene, and glycidyl methacrylate (GMA) was successfully initiated by the system consisting of Mo(CO)₆ and terminal trichloroacetyl groups of PAMAM-grafted silica. In the polymerization, the corresponding vinyl polymers were effectively postgrafted onto PAMAM-grafted silica, based on the propagation of polymer from surface radicals formed by the reaction of terminal trichloroacetyl groups with Mo(CO)₆: the percentage of PMMA postgrafting onto PAMAM-grafted silica reached to 400% after 30 min, but the formation of gel was observed after 35 min. The formation of gel tends to decrease by use of hyperbranched PAMAM-grafted silica with higher percentage of grafting. The vinyl polymer-postgrafted nano-sized silica gave a stable colloidal dispersion in various organic solvents.     

Simultaneous graft copolymerization of 2‐hydroxyethyl methacrylate and acrylic acid onto polydimethylsiloxane surfaces using a two‐step plasma treatment

Acrylic acid (AAc) and 2‐hydroxyethyl methacrylate (HEMA) mixtures were simultaneously grafted onto the surfaces of polydimethylsiloxane (PDMS) films using a two‐step oxygen plasma treatment (TSPT). The first step of this method includes: oxygen plasma pretreatment of the PDMS films, immersion in HEMA/AAc mixtures, removal from the mixtures, and drying. The second step was carried out by plasma copolymerization of preadsorbed reactive monomers on the surfaces of dried pretreated films. The effects of pretreatment and polymerization time length, monomer concentration, and ratio on peroxide formation and graft amount were studied. The films were characterized by attenuated total reflection Furrier transformer infrared (ATR‐FTIR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), zeta potential, surface tension, and water contact angle measurements. The ATR‐FTIR spectrum of the modified film after alkaline treatment showed the two new characteristic bands of PHEMA and PAAc. Both increase the polar part of surface tension (γ_p) after grafting and the evaluation of surface charge at pH 1.8, 7, and 12 confirmed the presence of polar groups on the surface of grafted films with a mixture of HEMA/AAc. Morphological studies using both AFM and SEM evaluation illustrated various amounts of grafted copolymer on the surface of PDMS films. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Surface grafting of poly(vinylamine) onto poly(ethylene) film by corona discharge‐induced grafting

Poly(vinylamine) (PVAm) was grafted on a poly(ethylene) (PE) film surface via the surface graft polymerization of N‐vinylformamide (NVF) and N‐vinylacetamide (NVA) and the subsequent hydrolysis of those grafted polymers. The surface was characterized by X‐ray photoelectron spectroscopy (XPS), contact angle, moisture absorption, and the leakage of electrostatic charge from the films. PNVF and PNVA were introduced onto the surface of the PE film successfully, in spite of the fact that the initiator for polymerization was a peroxide group. The grafted amounts of PNVF and PNVA were dependent on the grafting time. A PVAm‐grafted surface was obtained via the hydrolysis of the grafted PNVF. The grafted‐PNVA was not hydrolyzed under mild hydrolysis. The obtained PVAm‐grafted surface appeared to be useful for various applications, such as protein immobilization or chemical modification. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1583–1587, 1999