Monomers, grafting

Biopolymer Grafted monomers Method of Swelling in grafting2 water, ml g Refs. i... 

Graft copolymers of PAN with PMA have been synthesized by this method and branched PAN was obtained using AN as the grafted monomer. Fibres obtained from graft copolymers, irrespective of the nature of the grafted component, are superior to PAN fibres as far as their resistance to multiple deformations is concerned. 

The objective of recent DSM studies was to develop new EPM-based elastomers that have improved oil resistance. The idea was to develop such products by chemical modification of EPM copolymers using highly polar graft monomers, such as maleic anhydride (MA), and, optionally, by reacting these EPM-g-MA polymers with other chemicals as a way to (cross-Unk and) further enhance the polarity of the products. It is expected that the enhanced polarity will eventually lead to improved oil resistance of the final (cross-Unked) products, ft is noted that the EPM copolymers with extremely high MA graft levels as employed in this study are not commercially available. 

For the two methods, the resulting grafting of functional monomers, e.g. acrylic acid and acrylamide, has been measured by multiple reflection IR spectra, ESCA spectra, and dye adsorption from an aqueous solution of crystal violet. The measurements indicate that the inert surfaces of the polymer substrates are modified by a complete surface layer of the grafted monomers. 

Li, S., Zhou, Z., Liu, M. and Li, W. 2005. Heterocycle grafted monomers and related polymers and hybrid inorganic-organic polymer membranes. WO Patent 05072413. 

Deleuze et al. used the same approach for the synthesis and functionalization of emulsion-derived polymeric foams [119]. Alternatively, a post-synthesis grafting method recently developed in our group offers access to high-capacity functionalized monolithic systems. Such high capacity monoliths are vital to various applications such as catalysis, extraction of environmental contaminants, extraction of biochemicals for either pharmaceutical or clinical purposes or, more generally, separation techniques [100]. With these systems, amounts of grafted monomers can exceed 1 mmol/g [94]. 

Monomer Milling time h Interpolymer composition % Polyamide Graft monomer Solvent insoluble fraction composition % Polyamide Graft monomer Homopolymer %... 

The last of the direct methods for graft initiation in liquid phase presented in this review involves chemical additives. Either free radical or ionic initiators can be chosen. Benzoyl peroxide is reported for grafting styrene on Nylon fibers in methanol media (71,105-107), as well as vinyl acetate (106). Azoisobutyro-nitrile has been employed in systems where the graft monomer is styrene (71,106) or vinyl acetate (106). Redox systems involving hydrogen peroxide and monomers like styrene (106,108,109). vinyl acetate (106), acrylic acid (108,109), methyl... 

An anionic technique by indirect grafting was proposed for N-metallation of Nylon by Yamaguchi (153-155), in which alcali metals dissolved in liquid ammonia displace the amidic hydrogen atoms. Nylon derivatives and graft copolymers can be synthetized from the N-metallated Nylon (153). For ethylene oxide as grafting monomer, the metallated fibers were soaked in a tetrahydro-furan solution of the monomer, at 60° C (154). Methyl methacrylate is grafted on Nylon with a conversion over 90% by this technique (155). Other procedures involve the use of sodium methoxide in methanol solution and subsequent anionic graft copolymerization of acrylonitrile in a tetrahydrofuran solution (156). 

The following reaction schemes show the principle of the grafting reactions using azo-containing polymers, whereby the azo groups are used as initiatiors of the graft monomers. 

The range of the ratio backbone/grafted monomer is variable. 

After conversion had reached ca. 100%, the graft monomer (methacrylonitrile or styrene) was simply added to the emulsion and the temperature raised to 75 °C 32). This type of grafting is called in situ grafting (see Table 3.14). 

Polymers containing azo groups are employed either in a solvent or they can simply be dissolved in the graft monomer. In all cases which have been reported, the polymeric azo compounds have kinetic characteristics analogous to their low-molecular-weight analogues, i.e. they conform with the general formula ... 

Diene substrate latices were prepared by seeding techniques following the scheme shown in Figure 1. Persulfate anion was the initiator, and an alkyl aryl sulfonate was the emulsifier. Reaction time varied between 13 and 33 hours. Since all the substrates were prepared by similar techniques, the volumetric swell index and gel gravimetric data (toluene) varied little with particle size. Small differences in swell and gel characteristics should not be a variable in this study because of the polarity of the grafting monomer mixture and rapidity of the graft reactions. 

Polymer Experimental ozoniza-tion conditions Grafted monomer Experi- mental grafting conditions Application Ref. 

In order to limit extensive side reactions (advanced destruction of the support-polymer, modification of grafting monomers structure) which usually accompany grafting reactions in electrical discharge conditions, we have elaborated the solid-solid grafting procedure in cold plasma. Thus, the rayon fabric was grafted with halogen and phosphorus containing polymers in... 

Figure 1. The tensile strength of degraded cotton print cloth (50-Mrad dose) after application of various acrylic resins (A1-A4) and grafted monomers (M1-M4) U = untreated fabric, PE = polyethylene, AD — air dried. See text for identification of resins and monomers.

Series II Grafting Monomers. The second series of experiments involved padding the fabric with various monomers, followed by polymerization of the monomer inside the fabric to create a graft copolymer that might partially cross-link the fiber (6). It was hoped that cross-... 

The azo initiator was chosen in a way that the low molecular dinitrile radical formed after decomposition does not initiate fi ee radical formation. Therefore no homopolymer of the graft monomer in the graft products A-PC was found. However, in the case of the triazene initiator functions homopolymer formation can not be fully excluded in T-PC. Further studies on grafting efficiency, length and number of graft arms, and homopolymer formation, as well as on the initiator mechanism of the triazene functions are in progress. 

---