2024-03-28T12:22:02Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/449022022-11-17T02:08:08Zhdl_2115_20045hdl_2115_139Hyperbranched 5,6-glucan as reducing sugar ballTamaki, MasakiTaguchi, TsukasaNakabayashi, SoichiMori, KotaKitajyo, YoshikazuSakai, RyosukeKakuchi, ToyojiSatoh, Toshifumiopen accessPolym. Chem., 2010, 1, 82-92 – Reproduced by permission of The Royal Society of Chemistry431The ring-opening polymerization of 5,6-anhydro-1,2-O-isopropylidene-α-D-glucofuranose (1) as a latent cyclic AB2-type monomer was carried out using potassium tert-butoxide (t-BuOK) or boron trifluoride diethyletherate (BF3・OEt2) as an initiator in order to synthesize a novel hyperbranched glycopolymer. The anionic and cationic polymerizations proceeded via the proton-transfer reaction mechanism to produce the hyperbranched poly(5,6-anhydro-1,2-O-isopropylidene-α-D-glucofuranose) (2). In particular, the cationic polymerization with the slow-monomer-addition strategy is a facile method leading to the hyperbranched glycopolymers with high molecular weights and highly branched structures. The weight-average molecular weight (Mw,SEC-MALLs) values of 2 measured by multi-angle laser light scattering (MALLS) varied in the range from 7,400 to 122,400, which were significantly higher than the weight-average molecular weight (Mw,SEC) values determined by size exclusion chromatography (SEC). The intrinsic viscosities ([η]) of these polymers were very low in the range of 3.3-4.6 mL g^[-1] and the Mark-Houwink-Sakurada exponents α were calculated to be 0.08-0.27. These results of the MALLS, SEC, and viscosity measurements suggested that these polymers exist in a compact spherical conformation in solution because of their highly branched structure. The synthesis of the hyperbranched 5,6-glucan (3) by hydrolysis of polymer 2 was also demonstrated. Polymer 3 is a novel water-soluble hyperbranched glycopolymer arranged with numerous reducing D-glucose units on the peripheries of the polymer, and has a higher reducing ability than D-glucose because of the glycocluster effect or the multivalent effect of the reducing D-glucose units. Therefore, polymer 3 should be called a "reducing sugar ball".Royal Society of Chemistry2010-03engjournal articleAMhttp://hdl.handle.net/2115/44902https://doi.org/10.1039/b9py00223e1759-9954Polymer Chemistry118292https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/44902/1/PC1-1_82-92.pdfapplication/pdf1.86 MB2010-03