Molecularly Defined Caprolactone Oligomers and Polymers: Synthesis and Characterization

@article{citeulike:2320669, abstract = {Abstract: The synthesis of molecularly defined -caprolactone oligomers and polymers up to the 64-mer, via an exponential growth strategy, is described. By careful selection of orthogonal protecting groups, t-butyldimethylsilyl (TBDMS) ether for the hydroxyl group and benzyl (Bn) ester for the carboxylic acid group, a highly efficient synthetic strategy was developed with yields for both deprotection steps being essentially quantitative and for the coupling reactions using 1,3-dicyclohexylcarbodiimide (DCC), yields of 80-95\% were obtained even at high molecular weights. This allows monodisperse dimers, tetramers, octamers, 16-mers, 32-mers and 64-mers to be prepared in gram quantities and fully characterized using mass spectroscopy, size exclusion chromatography (SEC), and IR and NMR spectroscopy. Thermal and physical properties were measured using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), atomic force microscopy (AFM), and small-angle X-ray scattering (SAXS). These results conclusively show a distinct structure/property relationship with a close correlation between the number of repeat units and physical properties. In addition, a number of marked differences were observed on comparison with the parent poly(caprolactone) polymer.}, address = {Materials Research Laboratory and Departments of Materials, Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, and Mitsubishi Chemical Group Science and Technology Research Center, Inc., 1000 Kamoshida-cho, Aoba-ku, Yokohama, 227-8502, Japan}, author = {Takizawa, K. and Tang, C. and Hawker, C. J. }, citeulike-article-id = {2320669}, doi = {10.1021/ja077149w}, journal = {J. Am. Chem. Soc.}, keywords = {monodisperse}, month = {February}, number = {5}, pages = {1718--1726}, posted-at = {2008-02-01 21:22:24}, priority = {2}, title = {Molecularly Defined Caprolactone Oligomers and Polymers: Synthesis and Characterization}, url = {http://dx.doi.org/10.1021/ja077149w}, volume = {130}, year = {2008} }

TY - JOUR ID - citeulike:2320669 L3 - citeulike-article-id:2320669 TI - Molecularly Defined Caprolactone Oligomers and Polymers: Synthesis and Characterization JF - J. Am. Chem. Soc. VL - 130 IS - 5 SP - 1718 EP - 1726 AD - Materials Research Laboratory and Departments of Materials, Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, and Mitsubishi Chemical Group Science and Technology Research Center, Inc., 1000 Kamoshida-cho, Aoba-ku, Yokohama, 227-8502, Japan N2 - Abstract: The synthesis of molecularly defined -caprolactone oligomers and polymers up to the 64-mer, via an exponential growth strategy, is described. By careful selection of orthogonal protecting groups, t-butyldimethylsilyl (TBDMS) ether for the hydroxyl group and benzyl (Bn) ester for the carboxylic acid group, a highly efficient synthetic strategy was developed with yields for both deprotection steps being essentially quantitative and for the coupling reactions using 1,3-dicyclohexylcarbodiimide (DCC), yields of 80-95% were obtained even at high molecular weights. This allows monodisperse dimers, tetramers, octamers, 16-mers, 32-mers and 64-mers to be prepared in gram quantities and fully characterized using mass spectroscopy, size exclusion chromatography (SEC), and IR and NMR spectroscopy. Thermal and physical properties were measured using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), atomic force microscopy (AFM), and small-angle X-ray scattering (SAXS). These results conclusively show a distinct structure/property relationship with a close correlation between the number of repeat units and physical properties. In addition, a number of marked differences were observed on comparison with the parent poly(caprolactone) polymer. KW - monodisperse AU - Takizawa, K AU - Tang, C AU - Hawker, CJ PY - 2008/02/06/ UR - http://dx.doi.org/10.1021/ja077149w ER -