Preparation of gelatin–N-vinylpyrrolidone graft copolymer

The graft copolymerization of N-vinylpyrrolidone (VP) onto gelatin was carried out by the following four different initiator systems: AIBN, K₂S₂O₈, H₂O₂—Fe²⁺, and Ce⁴⁺—HNO₃. The last one caused the monomer to lose the double-bond and polymerization ability due to the hydrolysis of the monomer. Using α,α-azobisisobutyronitrile as an initiator, the graft copolymerization of gelatin and N-vinylpyrrolidone in aqueous medium was studied systematically. The relationships between the rate of grafting and the concentration of initiator, monomer, and gelatin were established experimentally. Meanwhile, the rate equation was also derived from the proposed reaction mechanism, and it was similar to the equation previously obtained experimentally. The apparent activation energies for homopolymerization (E_h), graft copolymerization (E_g), and over all polymerization (E_p) were calculated. The graft efficiency and molecular weight of the grafted PVP were measured by hydrolyzing the backbone with hydrochloric acid. The graft copolymers Gel-g-PVP were added into the coating films, and the physical properties of the films, such as hardening ability, dimensional stability, and wetting property were investigated. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1485–1492, 1998     

Grafting of polymeric side chains to gelatin

Kinetics of grafting of poly(butyl acrylate) onto gelatin was studied with H₂O₂—ascorbic acid redox systm. Percent grafting, grafting efficiency, R_g, and R_h were determined as a function of time, temperature, initiator, monomer, and backbone concentration. It was found that R_g depends on first power of monomer concentration and 0.5 power to the initiator concentrations. A detailed kinetic scheme is proposed to explain these results.     

Kinetics and mechanism of free radical grafting of methyl acrylate onto sago starch

The graft copolymerization was carried out by methyl acrylate with sago starch in which ceric ammonium nitrate was used as an initiator. It has been found that the rates of graft polymerization and grafting efficiency were dependent upon the concentration of ceric ammonium nitrate (CAN), methyl acrylate (MA), sago starch (AGU, anhydro glucose unit), mineral acid (H₂SO₄), and as well as reaction temperature and period. A rate equation of polymerization was established from the proposed reaction mechanism, and the rate of polymerization (R_p) was the first‐order dependence of the MA monomer concentration and square root of the CAN concentration. A new kinetic model of the grafting reaction has been proposed, and a normal kinetics of methyl acrylate polymerization was observed. An equation of a predicted model relating the graft fraction of poly(methyl acrylate) with the sago starch has been derived, and validity of the predicted model was verified by the experimental results. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 784–791, 2000     

Grafting vinyl monomers onto nylon 6. VI. Graft copolymerization of methyl methacrylate onto nylon 6 using acetylacetonate complex of Mn(III), Co(III), and Fe(III)

The graft copolymerization of methyl methacrylate onto nylon 6 using metal complexes of Mn³⁺, Co³⁺, and Fe³⁺ as initiators was studied. The rate of polymerization, R_p, increased with increasing complex concentrations in the initial stages; but it decreased upon further increase of complex concentrations. With increasing monomer concentrations, the rate of polymerization increased progressively. The graft yield increased with increaing temperature within the range 60–75°C. A suitable kinetic scheme is presented and rate equations are derived.     

Kinetics of ylide-initiated radical copolymerization of 4-vinylpyridine and methyl methacrylate

The ylide-initiated radical copolymerization of 4-vinylpyridine (4-VP) with methyl methacrylate (MMA) at 60°C using carbon tetrachloride as inert solvent yields non-alternating copolymers. The kinetic parameters, average rate of polymerization (R_p) and orders of reaction with respect to monomers and initiator, have been evaluated and the kinetic equation is found to be R_pα[ylide]^0.94 [MMA]^1.0 [4-VP]^1.5. The values of the energy of activation and k_p²/k_t are 48 kJ mol^?1 and 6.6 × 10^?5 litre mol^?1s^?1, respectively. The copolymers have been characterized by IR and NMR spectroscopy.     

Peroxydisulfate initiated graft copolymerization of aniline onto poly(propylene) fiber—A kinetic approach

A novel method for the preparation of electrically conducting fibers through chemical grafting of electrically conducting polymer onto poly(propylene) (PP) fiber is described. The graft copolymerization of aniline (ANI) was performed in aqueous acidic medium by using a chemical oxidant such as peroxydisulfate (PDS). Grafting occurred with simultaneous homopolymer formation. The content of polyaniline in the backbone fiber was found to vary by varying [monomer], [initiator], and amount of PP fiber. Various graft parameters such as rate of grafting (R_g), % grafting, and % grafting efficiency were evaluated. The rate of homopolymerization (R_h) was also determined. Both R_h and R_g showed first‐order dependency on [ANI], [PDS], and amount of PP fiber variation. The chemical grafting was confirmed by use of cyclic voltammetry and conductivity measurements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3827–3834, 2003     

Ceric ion‐induced graft copolymerization of acrylamide on cationic guar gum at low temperature

The solution polymerization of acrylamide (AM) on cationic guar gum (CGG) under nitrogen atmosphere using ceric ammonium sulfate (CAS) as the initiator has been realized. The effects of monomer concentration and reaction temperature on grafting conversion, grafting ratio, and grafting efficiency (GE) have been studied. The optimal conditions such as 1.3 mol of AM monomer and 2.2 × 10^?4 mol of CAS have been adopted to produce grafted copolymer (CGG1‐g‐PAM) of high GE of more than 95% at 10°C. The rates of polymerization (R_p) and rates of graft copolymerization (R_g) are enhanced with increase in temperature (<35°C).The R_p is enhanced from 0.43 × 10^?4 mol L^?1 s^?1 for GG‐g‐PAM to 2.53 × 10^?4 mol L^?1 s^?1 for CGG1‐g‐PAM (CGG1, degree of substitute (DS) = 0.007), and R_g from 0.42 × 10^?4 to 2.00 × 10^?4 mol L^?1 s^?1 at 10°C. The apparent activation energy is decreased from 32.27 kJ mol^?1 for GG‐g‐PAM to 8.09 kJ mol^?1 for CGG1‐g‐PAM, which indicates CGG has higher reactivity than unmodified GG ranging from 10 to 50°C. Increase of DS of CGG will lead to slow improvement of the polymerization rates and a hypothetical mechanism is put forward. The grafted copolymer has been characterized by infrared spectroscopy, thermal analysis, and scanning electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3715–3722, 2007     

Kinetics of dispersion polymerization of dimethyl diallyl ammonium chloride and acrylamide

Dispersion copolymerization of dimethyl diallyl ammonium chloride with acrylamide has been investigated by the dilatometer technique using the mixture of poly(vinylpyrrolidone) and poly(dimethyl diallyl ammonium chloride) as the composite stabilizer and 2,2′-azobis(2-methylpropionconidine)dihydro chloride as the initiator. Monomer reactivity ratios of AM and DMDAAC were determined by the application of Fineman-Ross methods. The analysis of reactivity ratios revealed that DMDAAC is less reactive than AM, and copolymers formed are statistically in nature. The influences of the molar ratio of AM to DMDAAC, concentrations of monomers, stabilizer and initiator, etc. on polymerization rate and intrinsic viscosity of polymer have been examined. The rate of polymerization (R_p) can be represented by R_p μ [M]^1.44,R_p μ [S]^0.39,R_p μ [I]^0.60 {R_{\rm{p}}} \propto {[M]^{1.44}},{R_{\rm{p}}} \propto {[S]^{0.39}},{R_{\rm{p}}} \propto {[I]^{0.60}} . The overall activation energy for the rate of polymerization is 37.38 kJ/mol over the temperature range 35–55°C.Based on the experimental results, the polymerization mechanisms were discussed.     

Kinetics of graft copolymerization of methyl methacrylate in wool fibers

The graft copolymerization of methyl methacrylate in wool fibers was investigated in the aqueous LiBr–K₂S₂O₈ system without homopolymer. The rate of grafting and the degree of polymerization of graft polymer were determined on varying the extent of reduction of wool fibers and the concentration of monomer. From the graft copolymerization behavior observed at a given concentration of redox catalysts (LiBr and K₂S₂O₈), the thiol groups in wool fibers were considered to play a role as a sort of catalyst of polymerization, not as the chain transfer agent, and also to give the grafting sites. So, the initiation process of grafting was assumed to be started by d[S·]/dt = k_i[SH]_eff, and the kinetic consideration was found to lead to the following expression in agreement with the experimental results: 1/DP = (k_t/k_p²[M]_fib²)R_p, where d[S·]/dt is the rate of formation of thiol radicals by radicalotropy to ? SH from SO₄^?., OH·, or Br·; k_i, k_p, and k_t are the rate constants of initiation, propagation, and termination, respectively; [SH]_eff and [M]_fib are the concentration of the effective thiol groups and the MMA monomers within the wool fibers, respectively; DP is the average degree of polymerization of graft polymers, and R_p the overall rate of grafting.     

Free‐radical copolymerization kinetics of acrylonitrile and methyl acrylate in [BMIM]BF4

The copolymerization of acrylonitrile (AN) and methyl acrylate (MA) was carried out in ionic liquid [BMIM]BF₄ in the presence of azobisisobutyronitrile (AIBN) as an initiator to investigate the polymerization kinetic, including the copolymerization rate, reactivity ratios, and activation energy. The copolymerization rate equation was established according to the effect of initiator and monomer concentrations on the conversion. The copolymerization rate R_p can be noted as , when the copolymerization was in the steady state. The apparent activation energy is 87.94 kJ/mol, while the value of that in the conventional organic solvent (DMF) is ∼ 81 kJ/mol. The reactivity ratios of the investigate system are r_AN = 0.36 and r_MA = 0.68. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4254–4257, 2006     

Graft copolymerization of p‐acryloyloxybenzoic acid and p‐methacryloyloxybenzoic acid onto isotactic polypropylene and their thermal properties: Part I

The polymerization and grafting of the monomers p‐acryloyloxybenzoic acid and p‐methacryloyloxybenzoic acid were studied. Poly(acryloyloxybenzoic acid) was obtained by γ‐radiation‐induced solution polymerization and bulk melt polymerization initiated by dicumyl peroxide. Poly(methacryloyloxybenzoic acid) could be obtained only by bulk melt polymerization. The graft copolymerization of the monomers onto isotactic polypropylene was carried out in bulk. The maximum grafting was reached in shorter times at higher temperatures, and it also increased with the concentration of the monomers in the reaction medium. The thermal and crystallization behavior of the graft copolymers was studied with differential scanning calorimetry and wide‐angle X‐ray diffraction. The graft copolymerization of p‐acryloyloxybenzoic acid did not have any influence on the formation of both α forms (monoclinic) of polypropylene, whereas p‐methacryloyloxybenzoic acid led to the α₂ form. The β‐crystalline modification (hexagonal) formed in poly(acryloyloxybenzoic acid)‐g‐polypropylene products at 185°C and at higher grafting temperatures and also in the second run of differential scanning calorimetry studies after fast cooling. The β form was not observed in graft copolymers of poly(methacryloyloxybenzoic acid). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Concentrated emulsion copolymerization of butyl acrylate and vinyl acetate initiated by a redox initiator at lower temperature

The concentrated emulsion copolymerization of butyl acrylate and vinyl acetate with an ammonium persulfate/sodium hydrogen sulfate mixture as a redox initiator, with a sodium dodecyl sulfate/cetyl alcohol mixture as a compound surfactant, and with poly(vinyl alcohol) as a liquid film reinforcer was carried out at lower temperature. In less than 3 h, the polymerization conversion was greater than 95%. The effects of the surfactant, the initiator, the volume fraction of the monomer, and the temperature on the stability of the concentrated emulsion, the kinetic process, and the average size of the latices were examined. The morphology of the polymer particles was observed by transmission electron microscopy, and the average size and distribution of the particle diameter were measured by photon correlation spectroscopy. The kinetic equation was R_p = k[M]^0.38[I]^0.89[E]^?0.80 at 30°C (where R_p is the polymerization rate, [I] is the initiator concentration, [M] is the monomer concentration, and [E] is the concentration of the compound surfactant), and the apparent activation energy was 22.69 kJ/mol. The thin‐layer polymerization of the concentrated emulsions, which enabled the removal of the heat of polymerization, was performed first. In comparison with test‐tube polymerization, thin‐layer polymerization provided a more regular morphology of the polymer particles. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 570–576, 2004     

Kinetics of azo‐initiated 1‐vinyl‐2‐pyrrolidone polymerizations at low conversions in aqueous media

The free‐radical polymerization behavior of 1‐vinyl,2‐pyrrolidone (NVP) was studied at low conversions, using capillary dilatometry. The aqueous media were kept at neutral pH and the studies were conducted isothermally, at 40 or 45°C. The azo‐type initiators used were 4,4′‐azobis‐4‐cyanopentanoic acid (ACPA), 2,2′‐azobisisobutyronitrile (AZBN), and 2,2′‐azobis[2‐(2‐imidazolin‐2‐yl)propane dihydrochloride] (ABDH). The monomer concentration and initiator concentration ranges were 1.17–2.34 mol L⁻¹ and 1–8 mmol L⁻¹, respectively. The rates of polymerization (R_p) and orders of reaction with respect to NVP and the initiator were evaluated and the kinetic equations were found to be R_p ∝ [NVP] [ACPA]^1.2; R_p ∝ [NVP] [AZBN]^1.1; and R_p ∝ [NVP]^2.2 [ABDH]^1.1. The polymers obtained were characterized by their viscosity numbers and correlation of the viscosity average molecular weights made with the type and amount of the azo initiator. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 239–246, 2000     

Phase‐transfer‐agent‐aided polymerization and graft copolymerization of acrylamide

The use of phase‐transfer catalysts, with water‐insoluble initiators, for polymerization and graft copolymerization reactions was explored. The polymerization of a water‐soluble vinyl monomer, acrylamide (AAm), and the graft copolymerization of AAm onto a water‐insoluble polymer backbone, isotactic polypropylene (IPP), with a water‐insoluble initiator, benzoyl peroxide (BPO), and a phase‐transfer catalyst, tetrabutyl ammonium bromide (Bu₄N⁺Br^?), were carried out in a water/xylene binary solvent system. The conversion percentage of AAm into polyacrylamide (PAAm) and the percentage of grafting of AAm onto IPP were determined as functions of various reaction parameters, such as the BPO, AAm, and phase‐transfer‐catalyst concentrations, the amounts of water and xylene in the water/xylene mixture, the time, and the temperature. The graft copolymer, IPP‐g‐PAAm, was characterized with IR spectroscopy and thermogravimetric analysis. By a comparison of the results of the phase‐transfer‐catalyzed graft copolymerization of AAm onto IPP and the preirradiation method, it was observed that the optimum reaction conditions were milder for the phase‐transfer‐catalyst‐aided graft copolymerization. Milder reaction conditions, including the temperature, the time of reaction, and a moderate initiator (BPO), in comparison with high‐energy γ‐rays, led to better quality products, and the reaction proceeded smoothly with high productivity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2364–2375, 2004     

Grafting of dichlorodimethylsilane onto cellulose acetate as a model system in homogeneous media

Homogeneous graft copolymerization of dichlorodimethylsilane (DCDMS) onto cellulose acetate (CA) was carried out in acetone. The weight conversion, grafting percentage and grafting efficiency were determined as functions of the polymerization temperature and the concentrations of monomer and cellulose acetate. The IR and NMR data of the graft copolymers showed peaks characteristic of grafted chains. The order of the solvents used for increasing the grafting yield values was found as follows: cyclohexanone > ethyl acetate > dioxane, which is in accordance with their dielectric constants. Cellulose acetate previously oxidized by treatment with a mixture of oxalic acid and potassium dichromate when grafted with DCDMS gave low grafting yield values. The rate of copolymerization grafting of DCDMS onto CA was determined (R_p = 1.1 %min⁻¹). The activation energy of the reaction between DCDMS and CA was calculated (1.32 kJ mol⁻¹, 0.32 kcal mol⁻¹). The mechanism of graft copolymerization of DCDMS onto CA is discussed.     

Grafting vinyl monomers onto polyester fibers. VI. Graft copolymerization of methyl methacrylate onto PET fibers using tetravalent cerium as initiator

The graft copolymerization of methyl methacrylate onto polyester fibers (PET) was investigated using tetravalent cerium as the initiator. The rate of grafting was found to increase progressively with the initiator and monomer concentrations up to 2.5 × 10^?2M and 70.41 × 10^?2M, respectively. The reaction was found to be catalysed by acid up to 15.0 × 10^?2M. The graft yield increased by increasing temperature. The effect of addition of some solvents and thiourea on the rate of grafting was also investigated. A suitable kinetic scheme has been pictured, and rate equations have been derived.     

Synthesis of polypropylene graft copolymers from a hydroxyl‐groups‐containing polypropylene precursor via atom‐transfer radical polymerization

Isotactic polypropylene graft copolymers, isotactic[polypropylene‐graft‐poly(methyl methacrylate)] (i‐PP‐g‐PMMA) and isotactic[polypropylene‐graft‐polystyrene] (i‐PP‐g‐PS), were prepared by atom‐transfer radical polymerization (ATRP) using a 2‐bromopropionic ester macro‐initiator from functional polypropylene‐containing hydroxyl groups. This kind of functionalized propylene can be obtained by copolymerization of propylene and borane monomer using isospecific MgCl₂‐supported TiCl₄ as catalyst. Both the graft density and the molecular weights of i‐PP‐based graft copolymers were controlled by changing the hydroxyl group contents of functionalized polypropylene and the amount of monomer used in the grafting reaction. The effect of i‐PP‐g‐PS graft copolymer on PP‐PS blends and that of i‐PP‐g‐PMMA graft copolymer on PP‐PMMA blends were studied by scanning electron microscopy. Copyright © 2006 Society of Chemical Industry     

Graft polymerization of acrylonitrile onto paper and characterization of the grafted product

The chemical graft copolymerization reaction of acrylonitrile (AN) onto paper sheet was performed. The effect of initiator concentration, monomer concentration, and temperature on the reaction rate was studied. The reaction rate equation of the graft copolymerization reaction is found to be R_P = K₂ [initiator]^0.54[monomer]^1.13. The apparent activation energy (E_a) of the copolymerization reaction is found to be 35.99 KJ/mol. The infrared characteristic absorption bands for cellulosic paper structure and the paper gr‐AN are studied. Tensile break load, porosity, and burst strength were measured for the grafted and pure paper sheet. It was found that the mechanical properties are improved by grafting. The chemical resistance of the graft product against strong acid (HCl), strong alkali (NaOH), polar and nonpolar solvents was investigated. It was found that the resistance to these chemicals is enhanced by grafting. From the TGA and DTA data, it is clear that the grafted paper sheet is more thermally stable than pure paper sheet. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Modified carrageenan. 4. Synthesis and swelling behavior of crosslinked κC‐g‐AMPS superabsorbent hydrogel with antisalt and pH‐responsiveness properties

To synthesize a novel biopolymer‐based superabsorbent hydrogel, 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) was grafted onto kappa‐carrageenan (κC) backbones. The graft copolymerization reaction was carried out in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator, N,N,N′,N′‐tetramethyl ethylenediamine (TMEDA) as an accelerator, and N,N′‐methylene bisacrylamide (MBA) as a crosslinker. A proposed mechanism for κC‐g‐AMPS formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The affecting variables on swelling capacity, i.e., the initiator, the crosslinker, and the monomer concentration, as well as reaction temperature, were systematically optimized. The swelling measurements of the hydrogels were conducted in aqueous solutions of LiCl, NaCl, KCl, MgCl₂, CaCl₂, SrCl₂, BaCl₂, and AlCl₃. Due to the high swelling capacity in salt solutions, the hydrogels may be referred to as antisalt superabsorbents. The swelling of superabsorbing hydrogels was measured in solutions with pH ranging 1 to 13. The κC‐g‐AMPS hydrogel exhibited a pH‐responsiveness character so that a swelling–deswelling pulsatile behavior was recorded at pH 2 and 8. The overall activation energy for the graft copolymerization reaction was found to be 14.6 kJ/mol. The swelling kinetics of the hydrogels was preliminarily investigated as well. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 255–263, 2005     

Kinetics and particle nucleation mechanism of St/BA/qBVPBr emulsifier‐free cationic emulsion polymerization

Stable functional cationic latices were prepared by emulsifier‐free emulsion copolymerization of styrene (St) and butyl‐acrylate (BA) with 1‐butyl‐4‐vinylpyridinium bromide (qBVPBr) as functional comonomer and azobis(isobutyramidine hydrochloride) (AIBA) as initiator at (70 ± 1)°C. The influences of the reaction temperature, the initiator concentration, and comonomer concentration on the polymerization conversion (x %), polymerization rate (R_p) of poly(St/BA/qBVPBr) emulsions were investigated. The results indicated that x % and R_p increase with increasing qBVPBr or AIBA concentration and temperature, and R_p can be expressed as R_p = K_p[AIBA]^0.73[qBVPBr]^0.08 (r_AIBA = 0.9968; r_qBVPBr = 0.9946, both r_AIBA and r_qBVPBr are linear correlation coefficient) and the apparent activation energy (E_a) is 47.89 kJ mol^?1. In the absence of emulsifier condition, curves of R_p versus reaction time obeyed the typical behavior characterized by Intervals I, II, and III as similar conventional emulsion polymerization. The formation and growth of poly(St/BA/qBVPBr) latex particles has been studied at different reaction times. The results indicate that N_p decrease gradually with time at the early polymerization stages and then reach a constant value after about 20% conversion, but D_p by photon correlation spectroscopy grow continuously as all polymerization proceed. Both the particle size distribution and molecular weight distribution curves are of bimodal size distribution and indicate the participation of at least two mechanisms of particle formation, namely, homogeneous nucleation in the aqueous phase and micellar nucleation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009