Synthesis and characterization of AB₂ an type functional β-cyclodextrin monomer and its water-soluble hyperbranched polymer

To obtain well-defined structures of a β-cyclodextrin based monomer and its hyperbranched polymer, an AB₂ type monomer carrying Si-H and -CH == CH₂ groups was first synthesized via modification of C-2 and C-6 hydroxyl groups in β-cyclodextrin, respectively. And then, the water-soluble hyperbranched polymer was prepared via hydrosilylation using N, N-dimethylformamide as the solvent and H₂PtCl₂ as the catalyst at 100°C. The molecular structures for both monomer and polymer were characterized by ¹H-NMR, ¹³C-NMR, MALDI-TOF MS and elemental analysi s. I t was found that the actual molecular structures for both monomer and polymer were identical with the designed structures, and there also existed α hydrosilylation and β hydrosilylation during polymerization, as a result, the hyperbranched polymer possesses a large amount of functional vinyl bonds around its end chains. The polymer synthesized is soluble in tetrahydrofuran slightly and insoluble in nonpolar solvents such as hexane. The molecular weight, molecular weight distribution and intrinsic viscosity of the polymer were measured as 36690, 1.887 and 15.8 mL/g, respectively by using size exclusion chromatography/multi-angle laser light scattering (SEC/MALLS) instrument. Due to two different cavities which are from β-cyclodextrin and the hyperbranched polymer, a possible novel spuramolecular system which may capsulize two more different molecules in a single polymer can be constructed.