ABSTRACT
A hyperbranched polymer consisting of rigid helical part chains was prepared as highly branched cyclic dextrin tris(phenylcarbamate) (HTPC) with the weight-average molar masses of 880 and 590 kg mol-1. Small-angle X-ray scattering (SAXS) measurement and viscometry were performed on the samples in good and poor solvents to determine the dimensional and hydrodynamic properties in solution. The HTPC molecule has a much more compact conformation than the linear chain with the same molar mass as expected for the hyperbranched architecture. While the corresponding linear polymer is soluble in methyl acetate (MEA) over a wide temperature range, HTPC is only soluble in the solvent at low temperatures. A typical LCST-type phase diagram was observed for the HTPC-MEA system, indicating that the interactions between the polymer segment of HTPC and the MEA molecules are substantially different from those of the linear chains. This is most likely due to the bending helical chains near the branching point of HTPC having different interactions with solvent molecules.
ABSTRACT
A hyperbranched polymer, highly branched cyclic dextrin tris(3,5-dimethylphenylcarbamate) (HDMPC), consisting of rigid rodlike subchains was synthesized to investigate dimensional and hydrodynamic properties of HDMPC in methyl acetate and 4-methyl-2-pentanone at 25 °C. Both gyration radii and intrinsic viscosities of the HDMPC sample in the two solvents were much smaller than those for the linear amylose tris(3,5-dimethylphenylcarbamate) (ADMPC) chain with the corresponding molar mass. The chiral column made of the HDMPC sample has chiral separation ability for 8 racemates with a mobile phase of hexane/2-propanol while 6 of them were also separated by our previously investigated linear ADMPC column. These results indicate that HDMPC retains the functionality of the rigid linear ADMPC chain with much smaller chain dimensions and lower solution viscosity than those for the linear chain with the same molar mass.