Poly grafting reactions

N. J. Earhart, The Grafting Reactions ofPoly(vinyl alcohol) During the Emulsion Copolymerisyation of Poly(vinyl acetate—co-butyl acrylate), Ph.D. dissertation. 

The structural effect of alkyl groups such as methyl, ethyl, and -butyl on the Rp is small. Alkyl 4-methyl-phenylcarbamate can be chosen as a model compound for the hard segment of poly(ether-urethane) (PEU). This group can initiate grafting reaction with Ce(IV) ion and the grafting site was proposed at the hard segment of PEU [3,15] as shown in Scheme (1). 

MMA and DMAPMA poly(MMA-co-DMAPMA) 23, obtained by radical copolymerization, can produce a photografting reaction with acrylonitrile (AN) using BP as the initiator [61]. The formation of a graft copolymer, poly[(MMA -c<7-DMAPMA)- -AN] was confirmed by FT-IR spectrophotometry. Based on ESR studies and end group analysis, the mechanism of grafting reaction is proposed as follows ... 

Anionic Polymerization. Anionic grafting polymerization initiated on the inorganic particles is also possible to give composite particles. The amino group incorporated into the surface of silica caused anionic polymerization of N-carboxy-a-amino acid anhydride to give poly(amino acid) grafting [Reaction (8)1 (21). 

The polymerization reaction in aqueous suspension of vinyl chloride in the presence of an ethylene-propylene saturated elastomer occurs with the formation of poly (vinyl chloride) homopolymer and rubber-poly (vinyl chloride) grafted copolymers. The first grafting reaction proceeds as far as diffusion of the monomer inside the particles in suspension is possible afterwards, some chain branching of grafted PVC is possible. Under our experimental conditions the amount of grafted rubber does not exceed 60% of the initial rubber and is little influenced by the type of initiator used. 

The thermal stability of poly(vinyl chloride) is improved greatly by the in situ polymerization of butadiene or by reaction with preformed cis-1,4-polybutadiene using a diethyl-aluminum chloride-cobalt compound catalyst system. The improved thermal stability at 3-10% add-on is manifested by greatly reduced discoloration when the modified poly-(vinyl chloride) is compression molded at 200°C in air in the absence of a stabilizer, hydrogen chloride evolution at 180°C is retarded, and the temperature for the onset of HCl evolution and the peak decomposition temperature (DTA) increase, i.e. 260°-280°C and 290°-325° C, respectively, compared with 240°-260°C and 260°-280°C for the unmodified homopolymer, in the absence of stabilizer. The grafting reaction may be carried out on suspension, emulsion, or bulk polymerized poly(vinyl chloride) with little or no change in the glass transition temperature. 

Secondary reactions of these types are widely used to produce polyphosphazenes that are required for biomedical applications or for polymer grafting reactions. They are also used to modify the surfaces of poly(organophosphazene), as discussed in the following section. 

Shieh Y-T, Tsai T-H (1998) Silane grafting reactions of low-density polyethylene. J Appl Poly Sci 69(2) 255-261... 

With thymine and uracil derivatives, graft reactions proceed almost quantitatively while in the case of the adenine derivative, its activated ester hardly reacts with poly-L-lysine, and only the copolymer with low adenine content is obtained, probably owing to the instability of the activated ester. Hypochromidty of the copolymer based... 

The free radical polymerization of styrene initialized by iniferter is influenced by chemical binding of iniferter on the surface of the silica." This reaction is used for grafting the polymer onto the surface of the silica. A similar approach is used when carbon whisker is incorporated during the graft-polymerization of methyl methacrylate. Depending on how the whisker is prepared, surface conversion can be increased up to twelve times compared to a polymerization with no whisker present. The addition of graphite to the poly esterification reaction doubles the molecular weight of the polymer. ... 

Doerffler and Patten have recently described a similar methodology for the formation of a less densely packed backbone where grafted polymers (macromolecules derived from only one monomer) were prepared strictly by ATRP [125]. The copolymerization of 4-acetoxymethyl- or 4-methoxymethylstyrene with styrene yielded a pendant functional macroinitiator with latent initiation sites . Transformation of the ester or ether to benzyl bromide substituents provided the alkyl halide necessary for the grafting reactions. The increased poly-dispersities observed above 20% monomer conversion were attributed to internal coupling reactions between the grafted chains. 

It has been demonstrated that hydrophobic, fluorinated, hyperbranched poly(acrylic acid) films can passivate and block electrochemical reactions on metal surfaces thus preventing surface corrosion [57]. Hyperbranched films can be synthesized on self-assembling monolayers on the metal surface via sequential grafting reactions to obtain thick and homogeneous films. 

---