Densely grafting copolymers of ethyl cellulose through atom transfer radical polymerization

Abstract

Densely grafting copolymers of ethyl cellulose with polystyrene and poly(methyl methacrylate) were synthesized through atom transfer radical polymerization (ATRP). First, the residual hydroxyl groups on the ethyl cellulose reacted with 2‐bromoisobutyrylbromide to yield 2‐bromoisobutyryloxy groups, known to be an efficient initiator for ATRP. Subsequently, the functional ethyl cellulose was used as a macroinitiator in the ATRP of methyl methacrylate and styrene in toluene in conjunction with CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine as a catalyst system. The molecular weight of the graft copolymers increased without any trace of the macroinitiator, and the polydispersity was narrow. The molecular weight of the side chains increased with the monomer conversion. A kinetic study indicated that the polymerization was first‐order. The morphology of the densely grafted copolymer in solution was characterized through laser light scattering. The individual densely grafted copolymer molecules were observed through atomic force microscopy, which confirmed the synthesis of the densely grafted copolymer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4099–4108, 2005

The preparation of graft copolymers of cellulose and cellulose derivatives using ATRP under homogeneous reaction conditions

“…The ATRP procedure used to graft St onto Br-ECs was the same as that reported by Shen et al 53 . Different lengths of PSt chains were achieved by varying for instance the reaction time, and/or the targeted DP.…”

“…In 2005, Shen et al 53 were the first to report the graft-copolymerisation from ethyl cellulose using ATRP. Densely grafted PSt-g-EC and PMMA-g-EC copolymers were prepared, where the macro-initiator Br-EC was synthesised under mild conditions using EC with a DS of 2.1.…”

“Green” Atom Transfer Radical Polymerization: From Process Design to Preparation of Well-Defined Environmentally Friendly Polymeric Materials

“…To accomplish the ATRP of the vinyl monomer, the hydroxy groups in the polysaccharide are converted to a 2-haloacid ester, affording a macroinitiator. Examples of polysaccharides modified with synthetic polymer side chains include cellulose [442][443][444] or ethylcellulose, 445 chitosan, 444,446-448 pullulan, 449 and cross-linked dextran 450 (see Scheme 13 for an example). The pullulan-polyHEMA graft copolymer conjugates obtained at different HEMA conversions were degraded in the presence of trifluoroacetic acid (at conditions at which polyHEMA itself was shown to be stable), and it was shown that the molecular weights of the yielded free polyHEMA were in agreement with the theoretically predicted ones and that the PDI values were low.…”

Synthesis and characterization of cellulose-b-polystyrene

“…12 However, there are few papers on cellulosic block copolymers, 13 in contrast to a large number of papers on cellulosic graft copolymers. [14][15][16][17][18] We synthesized cellulose-b-polystyrene by atom transfer radical polymerization (ATRP), a method that was developed by Wang and Matyjaszewski 19,20 and by Kato et al 21 This method is useful for preparing polymers with controlled molecular weight, polydispersity, composition and topology. It is also applicable to various combinations of vinyl monomers and solvents.…”