Molecular Design, Synthesis And Characterization Of Novel Graft Copolymers With Polyether (PEO) As Main Chain

Recently, various of linear and non-linear copolymers were designed and prepared owing to the development of synthetic technology, especially in the field of the controlled/"living" radical polymerization. Amphiphilic graft copolymers containing hydrophilic and hydrophobic chains have received much attention due to their unique structures, morphologies in solution as well as their potential applications in chemistry, physics, biology, and so on. However, most of these amphiphilic copolymers are composed of hydrophobic main chain and hydrophilic side chains. The inversed architecture graft copolymers with hydrophilic main chain and hydrophobic side chains are scarcely reported because of the difficulties of synthesis. Here, an efficient and universal method is introduced to synthesize the well-defined graft copolymer, three- and four-arm star graft copolymers with PEO as main chain. The essential work completed by us shows as follows:1. Some novel well-defined graft copolymers of poly(ethylene oxide) as main chain is successfully prepared by combination of anionic and atom transfer radical polymerization (ATRP). The glycidol is protected by ethyl vinyl ether first to form 2,3-epoxypropyl-1-ethoxyethyl ether (EPEE), then polymerized or copolymerized with EO by initiation with the mixture of diphenylmethylpotassium and triethylene glycol to give the well-defined poly(EO-co-EPEE). The latter is hydrolyzed in the acidic conditions, then the recovered copolymer of EO and glycidol (Gly) with multi pending hydroxymethyls [(poly(EO-co-Gly)] is esterified with 2-bromoisobutyrylbromide to produce the ATRP macroinitiator with multi pending bromoisobutyryl groups [poly(EO-co-Gly)(ATRP)]. Subsequently, the latter initiates the polymerization of styrene (St), methacrylate (MA), tert-butyl acrylate (tBA) and 2-(dimethylamino) ethyl methacrylate (DMAEMA) respectively to form the corresponding amphiphilic graft copolymer PEO-g-PS, PEO-g-PMA, PEO-g-PtBA and PEO-g-PDMAEMA. The double hydrophilic graft copolymer PEO-g-PAA is acquired by the hydrolysis of the amphiphilic graft copolymer PEO-g-PtBA. The polymerization kinetic of styrene and methacrylate initiated by poly(EO-co-Gly)(ATRP) are investigated respectively and found that both are well controlled. The object products and intermediates are characterized by ~1H NMR, IR, element analysis, GC-MS, MOLDI-TOF-MS and GPC in detail. It is proved that this route suggests to prepare the graft copolymers with PEO as main chain copolymer is successful.2. Two novel well-defined star-graft copolymers with poly(ethylene oxide) as main chain are successfully prepared by combination of anionic and atom transfer radical polymerization (ATRP). Anionic copolymerized 2,5-epoxypropyl-1-ethoxyethyl ether (EPEE) with EO by initiation of mixture of diphenylmethylpotassium and polyol [1,1,1-tris(hydroxymethyl)propane (TMP) or pentaerythritol] to give the well-defined three-arm star poly(EO-co-EPEE) and four-arm star poly(EO-co-EPEE). Both star copolymer precursors are hydrolyzed in the acidic conditions, then the corresponding recovered star copolymers of EO and glycidol (Gly) with multi pending hydroxylmethyls [three-arm star poly(EO-co-Gly) and four-arm star poly(EO-co-Gly)] are esterified with 2-bromoisobutyryl bromide to produce the ATRP macroinitiators with multi pending bromoisobutyryl groups [three-and four-arm star poly(EO-co-Gly)(ATRP)]. Then the latters initiate the polymerization of styrene (St) to form the corresponding amphiphilic three- and four-arm star PEO-g-PS. The object products and intermediates are characterized by ~1H NMR, IR and GPC in detail. It is proved that this method to synthesize the graft copolymers with PEO as main chain copolymer is successful.