Graft copolymer synthesis polymerization

The enzymatic polymerization of lactones could be initiated at the hydroxy group of the polymer, which expanded to enzymatic synthesis of graft copolymers. The polymerization of c-CL using thermophilic lipase as catalyst in the presence of hydroxyethyl cellulose (HEC) film produced HEC-gra/f-poly( -CL) with degree of substitution from 0.10 to 0.32 [102]. 

Such a two-component iniferter technique is also applied to the living radical polymerization of several DC photoiniferters for the design of block and graft copolymer synthesis (Sect. 5). 

The counter radical method can also be used for graft copolymer synthesis. Solomon et al. propose two routes [51]. The first one involves copolymerization with a functional monomer such as methacrylate containing pendant al-koxyamine. In the second route, the alkoxyamine is grafted onto a polymer precursor used in a second step to initiate the living polymerization of a second monomer. PBd-g-PMA is prepared this way from PBd. 

SCHEME 13.12 Photoinduced synthesis of block-graft copolymers using polymeric hydrogen donor and benzophenone. 

Polymerization Processes Aimed to Be Used in Graft Copolymer Synthesis... 

X)GHz. hi the presence of microwave radiation, selective excitation of the polar bonds takes place. This results in their rupture/cleavage, thus leading to formation of free radical sites. The C—C backbone of the preformed polymer being relatively nonpolar remains unaffected by the miaowave radiation. Recently, the microwave-irradiated method of graft copolymer synthesis has been classified into two types based on the generation of free radical sites on polymeric backbone. These are as follows ... 

Remarkable progress in block and graft copolymer synthesis was made in recent years by so-called living radical or controlled radical polymerization (GRP), which is based on the concept of reversible chain termination pioneered by Otsu and Yoshita [29]. 

PUrma, I. (ed.) (1992) Synthesis of amphipathic polymeric materials graft copolymers. In Polymeric Surfactants. Marcel Dekker, New York, pp. 35-48. 

Scheme 17 Graft copolymer synthesis using living insertion polymerization and ATRP.

Group-Transfer Polymerization. Living polymerization of acrylic monomers has been carried out using ketene silyl acetals as initiators. This chemistry can be used to make random, block, or graft copolymers of polar monomers. The following scheme demonstrates the synthesis of a methyl methacrylate—lauryl methacrylate (MMA—LMA) AB block copolymer (38). LMA is CH2=C(CH2)COO(CH2) CH2. 

Grafting provides a convenient means for modifying the properties of numerous polymers. It is often required that a polymer possess a number of properties. Such diverse properties may not be easily achieved by the synthesis of homopolymers alone but can be achieved through the formation of copolymers or even terpoly-mers. The formation of graft copolymer with sufficiently long polymeric sequences of diverse chemical composition opens the way to afford speciality polymeric materials. 

Corner, T. Free Radical Polymerization — The Synthesis of Graft Copolymers. Vol. 62, pp. 95— 142. 

The use of initiators such as 68 has been promoted for achieving higher molecular weights or higher conversions in conventional polymerization and for the production of block and graft copolymers. The use and applications of multifunctional initiators in the synthesis of block and graft copolymers is briefly described in Section 7.6.1. 

Anionic polymerization techniques can also be applied to the synthesis of graft copolymers 6 7 87 1U). Kennedy s classification 134) is used here as shown in Scheme 5. 

The purpose of this review is to show how anionic polymerization techniques have successfully contributed to the synthesis of a great variety of tailor-made polymer species Homopolymers of controlled molecular weight, co-functional polymers including macromonomers, cyclic macromolecules, star-shaped polymers and model networks, block copolymers and graft copolymers. 

Corner, T. Free Radical Polymerization — The Synthesis of Graft Copolymers. Vol. 62, pp. 95-142. Crescenzi, V. Some Recent Studies of Polyelectrolyte Solutions. Vol. 5, pp. 358-386. 

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