Solution copolymers, butyl synthesis

Product Identification was by GC/MS, NMR, and IR. Fundamental crosslinking chemistry was explored using swell measurements on simple solution copolymers and swell and tensile measurements with vinyl acetate (VAc), vinyl acetate/butyl acrylate (VAc/BA) or vinyl acetate/ethylene (VAE) emulsion copolymers. Polymer synthesis 1s described In a subsequent paper (6). Homopolymer Tg was measured by DSC on a sample polymerized In Isopropanol. Mechanistic studies were done 1n solution, usually at room temperature, with 1, 2 and the acetyl analogs 1, 2 (R =CH3). 

Park et al. [20] reported on the synthesis of poly-(chloroprene-co-isobutyl methacrylate) and its compati-bilizing effect in immiscible polychloroprene-poly(iso-butyl methacrylate) blends. A copolymer of chloroprene rubber (CR) and isobutyl methacrylate (iBMA) poly[CP-Co-(BMA)] and a graft copolymer of iBMA and poly-chloroprene [poly(CR-g-iBMA)] were prepared for comparison. Blends of CR and PiBMA are prepared by the solution casting technique using THF as the solvent. The morphology and glass-transition temperature behavior indicated that the blend is an immiscible one. It was found that both the copolymers can improve the miscibility, but the efficiency is higher in poly(CR-Co-iBMA) than in poly(CR-g-iBMA),... 

By employing anionic techniques, alkyl methacrylate containing block copolymer systems have been synthesized with controlled compositions, predictable molecular weights and narrow molecular weight distributions. Subsequent hydrolysis of the ester functionality to the metal carboxylate or carboxylic acid can be achieved either by potassium superoxide or the acid catalyzed hydrolysis of t-butyl methacrylate blocks. The presence of acid and ion groups has a profound effect on the solution and bulk mechanical behavior of the derived systems. The synthesis and characterization of various substituted styrene and all-acrylic block copolymer precursors with alkyl methacrylates will be discussed. 

GTP was employed for the synthesis of block copolymers with the first block PDMAEMA and the second PDEAEMA, poly[2-(diisopropylamino)e-thyl methacrylate], PDIPAEMA or poly[2-(N-morpholino)ethyl methacrylate], PM EM A (Scheme 33) [87]. The reactions took place under an inert atmosphere in THF at room temperature with l-methoxy-l-trimethylsiloxy-2-methyl-1-propane, MTS, as the initiator and tetra-n-butyl ammonium bibenzoate, TBABB, as the catalyst. Little or no homopolymer contamination was evidenced by SEC analysis. Copolymers in high yields with controlled molecular weights and narrow molecular weight distributions were obtained in all cases. The micellar properties of these materials were studied in aqueous solutions. 

Oxonium salts have been used as initiators in the polymerization of sulfides and amines as low-molecular-weight compounds (e.g. Et3OeBFJp)15,16) and as dicatio-nically living polyTHF 17,18) in the synthesis of diblock and triblock copolymers. Among alkyl esters and halides, tosylates, iodides, bromides, fluorosulfonates, and triflates were used in the polymerization of azetidines4,9,10 and aziridines 19,20). Methyl triflate forms the first alkylation product in the polymerization of 1-t-butyl-aziridine, which precipitates out of solution 19) ... 

Combination of anionic polymerization and post polymerization reactions has been used for the synthesis of poly(acrylic acid-b-N,N-diethylacrylamide) (PAA-PDEA) copolymers [9]. Initially the synthesis of a precursor poly(tert-butylacrylate-b- N,N-diethylacrylamide) (PtBMA-PDEAAm) block copolymer was realized via sequential anionic polymerization of the tert-butyl acrylate and diethylacrylamide monomers. However, an amount of PtBMA homopolymer was detected in the crude reaction product. In order to remove the vast majority of the homopolymer, the authors proposed the precipitation of the crude product in hexane, where the homopolymer is highly soluble, in contrast to the block copolymer. The piuified block copolymer was subjected to deprotection of the tert-butyl group in acidic media, leading to the desirable DHBC. The final block copolymer showed pH and thermosensitive solution aggregation. 

A similar procedure has been presented by the same group for the synthesis of another block copolymer, namely poly[4-vinylbenzoic acid-block-2-N-(morpholino)ethyl methacrylate] (PVBA-PMEMA). The protection of the VBA monomer with a tert-butyl group is essential for the synthesis of the desired copolymer, otherwise a mixture of PVBA-PMEMA diblock and PVBA homopolymer was obtained. The particular copolymer is expected to have interesting solution properties since the PVBA block is a week polyacid, while PMEMA is a conjugated acid, soluble over a wide pH range at room temperature and in the absence of salt [14]. 

Latex with hydroxyl functionalised cores of a methyl methacrylate/butyl acrylate/2-hydroxyethyl methacrylate copolymer, and carboxyl functionalised shells of a methyl methacrylate/butyl acrylate/methacrylic acid copolymer was prepared by free radical polymerisation. The latex was crosslinked using a cycloaliphatic diepoxide added by three alternative modes with the monomers during synthesis dissolved in the solvent and added after latex preparation and emulsified separately, then added. The latex film properties, including viscoelasticity, hardness, tensile properties, and water adsorption were evaluated as functions of crosslinker addition mode. Latex morphology was studied by transmission electron and atomic force microscopy. Optimum results were achieved by introducing half the epoxide by two-step emulsion polymerisation, the balance being added to the latex either in solution or as an emulsion. 8 refs. 

Kee, R.A. and Gauthier, M. (2008) Arborescentpolystyrene-gra -poly(/cr(-butyl methacrylate) copolymers Synthesis and enhanced polyelectrolyte effect in solution. Journal of Polymer Scierwe, Part A Polymer Chemistry, 46,2335-2346. 

Lodge, T.P., Bang, J.A., Li, Z.B. et al. (2005) Strategies for controlling intra- and intermicellar packing in block copolymer solutions Illustrating the flexibility of the self-assembly toolbox. Faraday Discussions, 128,1-12. Lu, Z.H., Liu, G.J., and Duncan, S. (2004) Polysulfone-graft-poly(tert-butyl acrylate) Synthesis, nanophase separation, poly(tert-butyl acrylate) hydrolysis, and pH-dependent iridescence. Macromolecules, 37,174—180. 

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