Experimental and theoretical studies of scaling of sizes and intrinsic viscosity of hyperbranched chains in good solvents
Publication in refereed journal



摘要Using a set of hyperbranched polystyrenes with different overall molar masses but a uniform subchain length or a similar overall molar mass but different subchain lengths, we studied their sizes and hydrodynamic behaviors in toluene (a good solvent) at T = 25 degrees C by combining experimental (laser light scattering (LLS) and viscometry) and theoretical methods based on a partially permeable sphere model. Our results show that both the average radii of gyration (< Rg >) and hydrodynamic radius (< Rh >) are scaled to the weight-average molar mass (Mw) as < R-g > similar to < R-h > similar to (MwMw,s phi)-M-gamma with gamma = 0.47 +/- 0.01 and phi = 0.10 +/- 0.01; and their intrinsic viscosity ([eta]) quantitatively follow the Mark- Houwink-Sakurada (MHS) equation as [eta] = K-eta M-w M-nu(w,s) (mu) with K-eta = 2.26 x 10(-5),. nu = 0.39 +/- 0.01, and mu = 0.31 +/- 0.01, revealing that these model chains with long subchains are indeed fractal objects. Further, our theoretical and experimental results broadly agree with each other besides a slight deviation from the MHS equation for short subchains, similar to dendrimers, presumably due to the multi- body hydrodynamic interaction. Moreover, we also find that the average viscometric radius (< R-eta >) determined from intrinsic viscosity is slightly smaller than < R-h > measured in dynamic LLS and their ratio (< R eta >/< Rh >) roughly remains 0.95 +/- 0.05, reflecting that linear polymer chains are more draining with a smaller < R-h > than their hyperbranched counterparts for a given intrinsic viscosity. Our current study of the " defect- free" hyperbranched polymer chains offers a standard model for further theoretical investigation of hydrodynamic behaviors of hyperbranched polymers and other complicated architectures, in a remaining unexploited research field of polymer science. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4795577]
著者Li LW, Lu YY, An LJ, Wu C
期刊名稱Journal of Chemical Physics
出版社AIP Publishing
Web of Science 學科類別Chemistry; Chemistry, Physical; Physics; Physics, Atomic, Molecular & Chemical; PHYSICS, ATOMIC, MOLECULAR & CHEMICAL

上次更新時間 2020-17-10 於 01:12