(Photo) graft copolymerization of methyl methacrylate (MMA) on polyamine-modified oxycellulose in a limited aqueous system

Graft copolymerization of methyl methacrylate (MMA) on oxycellulose modified with a polyamine [diethylene triamine (DETA)] was studied in a limited aqueous system under photoactivation in visible light using K₂S₂O₈ as the intiator. No polymerization was observed in the dark or in presence of light in 80 min in the case of DETA-treated cellulose; however, ready graft copolymerization resulting in high percent grafting and grafting efficiencies took place in the case of DETA-modified oxycellulose system under photoactivated conditions. DETA-modified oxycellulose prepared from oxycellulose corresponding to low degrees of oxidation (copper nos. 1.5–3.5) produced optimum grafting. The grafting parameters under different sets of conditions were studied and compared, and the mechanism of graft copolymerization was discussed.     

Oxidized cellulose: An application in the form of sorption filter materials

Oxidized cellulose (oxycellulose) was very effectively used in the form of filter sheets to remove some metal ions from water and from aqueous solutions. Furthermore, oxycellulose was applied in an ion‐exchange column and in a batch process. The mechanisms of the sorption process inside oxycellulose as well as the kinetics of sorption were studied. A comparison of oxycellulose and other adsorption components such as zeolites and ion‐exchange resins was made. The affinity of oxycellulose to metal ions was determined to be in the following order: Cd²⁺, Zn²⁺ > Ni²⁺ ? Ca²⁺ > Mg²⁺ ? Na⁺. The use of oxycellulose was very effective, especially in the form of sorption filters, because this allowed us to use a simple filtration process. Moreover, the specific loading amount of the filter cake was higher for filtration than for the column process under comparable conditions. Oxycellulose in a glass column behaved similarly to an ion‐exchange resin. It showed approximately constant efficiency until the sorption capacity of the adsorbent was exhausted, and then it suddenly dropped. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Radical polymerization in the presence of complexing agents. II. Copolymerization of methyl methacrylate-allyl methacrylate in the presence of zinc chloride

Radical copolymerization of methyl methacrylate (MMA)-allyl methacrylate (AMA) in the presence of zinc chloride, using azoisobutyronitrile (AIBN) as initiator has been carried out. The copolymerization rate increases with the concentration of ZnCl₂ and the reactivity ratios are modified by the concentration of ZnCl₂ which is explained by the different tendency towards the formation of complexes between MMA and AMA with ZnCl₂.     

Indirekte klassifikation von sechs oximierenden aldehydgruppen in oxycellulose nach dem polymerisationsgrad

The consecutive oximation at 20, 23, 25, 28, 30, and 35°C enabled the qualitative and quantitative differentiation of six various aldehydic groups in oxycellulose. For the calculation of the content b_n of the n^th aldehydic group a modified calculation method was used according to an improved equation. The proposed procedure enabled the characterization of the chemical structure of six various aldehydic groups in the oxycellulose macromolecule. Straight line dependences were found between the logarithm of those aldehydic group contents, as well as of the aldehyde sum values and the logarithms of the polymerization degree (DP), enabling an indirect and fast classification of oxycellulose aldehydes according to the DP-value. A computer calculation program was worked out enabling the determination of aldehyde groups according to the indirect procedure using the DP-value.     

Radical polymerization of mono- and di-methacrylic esters containing bisphenol-S

Radical polymerizations of mono- and di-methacrylic esters containing bisphenol-S (BPS-M and BPS-DM) were studied in terms of polymerization rate, solvent effect, copolymerization and kinetic measurements of photocrosslinking. The solvents were found to affect significantly the polymerization rate. Polar solvents such as DMSO and acetonitrile were found to slow down the polymerization rate. Copolymerization of BPS-M(M₁) with MMA(M₂) was studied in acetone at 60°C. The monomer reactivity ratios were calculated to be r₁ = 3.72 ± 0.01 and r₂ = 0.80 ± 0.01 by the Fineman-Ross method. The high reactivity of BPS-M observed in this copolymerization system may be due to the “matrix effect”. Functional polymers containing methacrylate side-groups were successfully modified and photocrosslinked by irradiation in the presence of benzoin isopropyl ether. The photocrosslinking process is found to be of second order kinetics.     

Copolymerization of tetrahydrofuran and propylene oxide

Summary Copolymerization of tetrahydrofuran and propylene oxide catalyzed by modified H₂SO₄.SO₃ system has been studied. Sodium perchloride was used to replace perchloric acid as co-catalyst. The copolymerization rate was obviously accelerated when using the new H₂SO₄.SO₃–NAClO₄ catalyst system. The reaction became less sensitive to the moisture.     

Copolymerization of Propylene with 1-Hexene and 4-Methyl-1-Pentene in Liquid Propylene Medium. Synthesis and Characterization of Random Metallocene Copolymers with Isotactic Propylene Sequences

Summary Propylene copolymerization with 1-hexene and 4-methyl-1-pentene in liquid propylene medium in presence of MAO-activated C₂-symmetry ansa-zirconocene rac-Me₂Si(4-Ph-2-MeInd)₂ZrCl₂ was studied. Random copolymers of propylene with 1-hexene and 4-methyl-1-pentene content up to 7 mol % were obtained at 60 °C. General kinetic characteristics of propylene/higher α-olefin copolymerization were evaluated. The distinct feature of propylene copolymerization with 1-hexene and 4-methyl-1-pentene in liquid propylene medium – the proximity of comonomer relative reactivity ratios (r₁∼r₂∼1) that indicates azeotropic nature of copolymerization processes in studied conditions. Synthesized copolymers were characterized with the use of IR, ¹³C NMR, GPC, WAXD, DSC techniques, and uniaxial tensile testing.     

Solution properties of hydrophobically modified polyelectrolytes synthesized via solution and micellar copolymerization

Hydrophobically modified polyelectrolytes (HMPEs) were synthesized using sodium 2‐acrylamido‐2‐methyl‐propanesulfonate and N‐n‐dodecylacrylamide as monomers with the same feeding ratio via micellar and solution copolymerization. The effects of hydrophobic association and electrostatic interaction on the solution properties of the HMPEs were studied. Compared with HMPE obtained via solution copolymerization (s‐PAD), the hydrophobic interaction of HMPE obtained via micellar copolymerization (m‐PAD) is more obvious due to the micro‐blocky distribution of hydrophobic groups. The viscosity properties of m‐PAD in deionized water or brine follow well the scaling theory of polyelectrolytes. However, for s‐PAD, the concentration where zero‐shear viscosity (η₀) and solvent viscosity (η_s) follow η₀ ≈ 2η_s is more likely to be critical entanglement concentration (c_e) rather than critical overlap concentration (c*). It is suggested that modifying of the transition region from c* to c_e is valid and reasonable for s‐PAD. It is believed that the different solution properties of s‐PAD and m‐PAD should be attributed to the distributions of hydrophobic groups in the chains. Copyright © 2010 Society of Chemical Industry     

Copolymerization of ethylene/1-hexene with zirconocene/MAO catalyst supported on spherical zirconia modified with BCl3, SiCl4, and glycerol

The spherical zirconia modified with BCl₃, SiCl₄, and glycerol was used as the support for rac-Et(Ind)₂ZrCl₂ catalyst to catalyze the copolymerization of ethylene/1-hexene. It is aimed to investigate the modification effects from different modifiers on copolymerization behaviors and compare the results with the unmodified system. The modified supports show higher activity than the unmodified one. Especially, the SiCl₄ modification exhibited the highest activity and produced copolymer with the largest 1-hexene insertion. This can be attributed to stronger interaction between the support and MAO along with the presence of SiCl₄ as a spacer group resulting in the absence of induction period. The modification did not affect the copolymers microstructure and the random copolymers were obtained from all supported systems. The narrower molecular weight distribution can be obtained from the modified supports. Besides, BCl₃ modification presents the highest molecular weight of polymer probably due to BCl₃ suppressing chain transfer reactions.     

Surface organic modification of titanium dioxide fine particles through photo polymerization

C?C unsaturated groups were chemically inserted onto TiO₂ particles surfaces through chemical reaction of hydroxyl group on the TiO₂ fine particle surface with 2,4‐diidocyanatotoluene (TDI) first, and then with 2‐hydroxyethyl acrylate (HEA). Finally, TiO₂ fine particles with surface organic modification were made through the free radical copolymerization reaction with n‐butyl acrylate (BA) monomer under UV irradiation. The structure and properties of unmodified and modified TiO₂ were studied by FT‐IR, XPS, TGA, TEM, lipophilic rates, and adhesion properties tests. The results show that the surface of TiO₂ has been successfully introduced with the organic chains through chemical bonding linkage; the surface lipophilic rates of TiO₂ particles are increased. The dispersion and compatibility of the modified TiO₂ particles in a commercial ink 508C resin greatly improve as compared with that of unmodified TiO₂, and agglomeration of particles obviously reduces. The adhesion strength between the white printing ink made from the modified TiO₂ particles and BOPP is much better than that from the unmodified TiO₂. When the organic rate reached 24.93%, the adhesion strength reaches Grade I. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Grafting of styrene/maleic anhydride copolymer onto PVDF membrane by supercritical carbon dioxide: Preparation,characterization and biocompatibility

Herein we report the surface modification of poly(vinylidene fluoride) (PVDF) microporous membrane via thermally induced graft copolymerization with maleic anhydride (Man)/styrene (St) in supercritical carbon dioxide (SC CO₂). SC CO₂, as a solvent and carrier agent, could accelerate mass transfer of monomers inside polymer matrixes and then facilitate the graft copolymerization on the surface of the membrane and within membrane pores, which were confirmed by FT-IR/ATR and XPS spectra together with SEM photographs. The effects of SC CO₂ pressure and temperature and the monomer concentration on the graft copolymerization were investigated. The modified PVDF membranes containing from 0 to 7 wt.% of grafted St–Man copolymer (SMA) were prepared and analysed in terms of surface microstructure, composition, hydrophilicity and biocompatibility. Solid-state ¹³C CP/MAS NMR and DSC indicated that the grafted SMA on the PVDF membrane had the alternative sequence structure and formed the different phases in the modified membrane, where the grafted SMA was associated with T_g of 122.8 °C and the PVDF matrix with T_m of 161.2 °C. The static contact angle measurements revealed that remarkable and permanent hydrophilicity was obtained upon grafting SMA. The experiments of BSA adsorption and cell growth also showed that the surface of SMA-based PVDF membrane has excellent biocompatibility.     

Graft Copolymerization of Acrylonitrile on Chemically Modified Sisal Fibers

Graft copolymerization of acrylonitrile (AN) on chemically modified sisal fibers was studied using a combination of NaIO₄ and CuSO₄ as initiator in an aqueous medium in the temperature range of 50–70°C. Effects of reaction medium, variation of time and temperature, concentration of CuSO₄, NaIO₄ and AN, and the amount of sisal fiber on the percentage of graft yield have been investigated. Water absorption (%) and tensile properties such as tensile strength, Young's modulus and extension at break of untreated, chemically modified and AN‐grafted sisal fibers were evaluated and compared. FTIR spectroscopy and scanning electron microscopy (SEM) of the chemically modified and AN‐grafted sisal fibers have been carried out.     

Porous polymers prepared via high internal phase emulsion polymerization for reversible CO2 capture

A series of porous polymers with different pore volumes, pore sizes, and crosslinking densities were synthesized by high internal phase emulsion (HIPE) polymerization. The crosslinked polymerized HIPEs (polyHIPEs) were formed by the copolymerization of 4-vinylbenzyl chloride and divinylbenzene using water droplets in conventional or Pickering HIPEs as the templates. These porous materials were further modified by quaternization and ion exchange to introduce quaternary ammonium hydroxide groups. The resulting polyHIPEs were utilized as sorbents for reversible CO₂ capture from air using the humidity swing. The effect of pore structure on the CO₂ adsorption and desorption processes was studied. The polyHIPEs containing large pores and interconnected porous structures showed improved swing sizes and faster adsorption/desorption kinetics of CO₂ compared to a commercial Excellion membrane with similar functional groups.     

Antibacterial activity of modified polyamide fibers

Polyamide fibers were modified for the attainment of antibacterial activity using a graft copolymerization method. The fibers were grafted with monomers containing quaternary ammonium groups using sodium persulfate as initiator. Two monomers were used as vinyl monomers. The first monomer, called METAC, is methacryloyloxyethyl trimethylammonium chloride [H₂C = C(CH₃)‐ CO₂CH₂CH₂N(CH₃)₃Cl]. The second monomer, denoted CATAL, is a methacryloyloxyethyl dimethyldodecylammonium bromide [H₂C = C(CH₃)CONHCH₂CH₂CH₂N‐ (CH₃)₂(C₁₂H₂₅)Br], kindly supplied by Catalyze (France). The graft copolymerization was confirmed by several methods such as elemental analysis and FTIR spectroscopy. The antibacterial activity of modified samples was investigated against Staphylococcus aureus using the antibacterial standard AFNOR test method XP G39–100. Polyamide fibers grafted with the second monomer exhibit high antibacterial activity against S. aureus, but the fibers grafted with the methacryloyloxyethyl trimethylammonium chloride did not. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 997–1000, 2005     

Graft copolymerization of acrylamide on cotton cellulose in a limited aqueous system following pretreatment technique

Graft copolymerization of acrylamide on cotton (dialdelyde cellulose, DAC) fibers and fabrics was studied in a limited aqueous system using K₂S₂O₈ as the initiator. Grafting parameters under different sets of conditions were determined and the mechanism of graft copolymerization discussed. Optimum conditions for grafting were established and the effect of polyacrylamide grafting on tenacity, modulus, breaking elongation, and stiffness of the cotton (DAC) fabrics and on their dyeability and moisture regain properties were also studied; 9–10% grafting of polyacrylamide on (DAC) fabric at _pH 7–10 imparts an improved balance in its mechanical and other properties. © 1995 John Wiley & Sons, Inc.     

Synthesis and characterization of novel type poly (4-chloromethyl styrene-grft-4-vinylpyridine)/TiO2 nanocomposite via nitroxide-mediated radical polymerization

This paper describes the synthesis and characterization of novel type poly (4-chloromethyl styrene-graft-4-vinylpyridine)/TiO₂ nanocomposite. Firstly, poly (4-chloromethyl styrene)/TiO₂ nanocomposite was synthesized by in situ free radical polymerizing of 4-chloromethyl styrene monomers in the presence of 3-(trimethoxysilyl) propylmethacrylate (MPS) modified nano-TiO₂. Thereafter, 1-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO-OH) was synthesized by the reduction of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO). This functional nitroxyl compound was covalently attached to the poly (4-chloromethyl styrene)/TiO₂ with replacement of chlorine atoms in the poly (4-chloromethyl styrene) chains. The controlled graft copolymerization of 4-vinylpyridine was initiated by poly (4-chloromethyl styrene)/TiO₂ nanocomposite carrying TEMPO groups as a macroinitiators. The coupling of TEMPO with poly (4-chloromethyl styrene)/TiO₂ was verified using ¹H nuclear magnetic resonance (NMR) spectroscopy. The obtained nanocomposites were studied using transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectra, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and the optical properties of the nanocomposites were studied using ultraviolet-visible (UV-Vis) spectroscopy.     

Radiation-induced copolymerization of vinylphosphonic dichloride with methyl methacrylate and styrene

The γ-ray-induced copolymerization of vinylphosphonic dichloride (VPDC) with methyl methacrylate (MMA) and styrene (St) was studied at 25°C (liquid phase) and ?78°C (Solid phase). The reaction mechanisms are discussed. The reactivity ratios for the copolymerization of the VPDC–MMA system were determined as follows: The difference between the reactivity between the liquid-phase (25°C) and solid-phase (?78°C) copolymerization is mainly attributable to the r₂ value. The behavior of the liquid-phase copolymerization of the VPDC–St system was anomalous, the r₁ value being negative in the range from 0 to 80 mole-% of VPDC monomer. In the solid-phase (?78°C) copolymerization for the VPDC–St system, the reactivity ratios r₁ and r₂ were 0.097 and 1.6, respectively. The rate of copolymerization (R_p) at 25°C, for both the VPDC–MMA and VPDC–St systems, passes a maximum point at a certain monomer concentration, suggesting that the composition of copolymer is considerably affected by R_p. This phenomenon was interpreted by the assumption that an energy transfer reaction from VPDC monomer to the other vinyl compound can easily occur.     

Grafting of acrylonitrile onto styrene-maleic acid copolymer by tetravalent cerium ion

The graft copolymerization of acrylonitrile (AN) onto a styrene-maleic acid copolymer (SY-MAc) with ceric ammonium nitrate (CAN) as a redox initiator in an aqueous medium has been studied. The effects of various reaction parameters, including reaction time and temperature, concentrations of initiator, nitric acid, and monomer, on the grafting yields and the rates of polymerization (R_p), graft copolymerization (R_g), and homopolymerization (R_h) were studied systematically. The results are discussed. The kinetic scheme of free-radical graft copolymerization has been proposed and the equations relating the values of R_p, R_g, and R_h are also suggested. The experimental results are found to be in good agreement with the proposed kinetic scheme. The activation energies of graft copolymerization and total polymerization are calculated. © 1995 John Wiley & Sons, Inc.     

Synthesis and characterization of copolymers of 5,6-benzo-2-methylene-1,3-dioxepane and n-butyl acrylate

The ATRP copolymerization of 5,6-benzo-2-methylene-1,3-dioxepane (BMDO) with n-butyl acrylate (nBA) was studied by using ethyl 2-bromoisobutyrate (EBriBu) and N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA)/Cu(I)Br as the initiator and catalyst, respectively. The reactivity ratios of the monomers in the copolymerization were determined using the Kelen-Tüdõs method and were found to be r_BMDO=0.08 and r_nBA=3.7. The copolymer yield decreased with higher amounts of BMDO in the initial feed. The structure of these copolymers was thoroughly characterized by 1D and 2D NMR techniques and quantitative ring opening of BMDO in its copolymerization was demonstrated. The hydrolytic degradation behavior of the BMDO/nBA copolymers was also studied.     

Functionalization of polyethylene using borane reagents and metallocene catalysts

A new method to prepare functionalized polyethylene involving borane intermediates and transition metal catalysts is described. Two processes, direct and post polymerizations, were employed to prepare borane-containing polyethylene (PE-B), which can be transformed to functionalized polyethylene (LLDPE-f) with various functional groups, such as ? BR₂, ? OH, ? NH₂, ? OSi(CH₃)₃. In the direct process, the PE-B copolymers were prepared in one step by copolymerization of ethylene with a borane monomer (ω-borane-α-olefin). The post polymerization process requires two steps: copolymerization of ethylene and 1,4-hexadiene, and subsequential hydroboration reaction of unsaturated PE. Three transition metal catalysts, including two homogeneous metallocene (Cp₂ZrCl₂ [bis(cyclopentadienyl) zirconium dichloride] and Et(Ind)₂ZrCl₂ [1,1′-ethylenedi-η⁵-indenyl-zirconium dichloride] with MAO (methylaluminoxane)) and one heterogeneous (TiCl₃·AA/Et₂AlCl) ones, were studied in the copolymerization reactions. The single site Et(Ind)₂ZrCl₂/MAO homogeneous catalyst, with a strained ligand geometry and opened active site, is by far the most effective system in the incorporation of high olefins into polyethylene structures.