Arborescent polymers poly

This chapter focuses on the latest efforts in our laboratory aimed at the synthesis and the physical characterization of arborescent polymers. The synthesis of arborescent styrene and isoprene homopolymers is discussed, together with copolymers incorporating a polystyrene substrate grafted with side chains of different compositions such as poly(2-vinylpyridine). 

The solution properties of dendrigraft polybutadienes are, as in the previous cases discussed, consistent with a hard sphere morphology. The intrinsic viscosity of arborescent-poly(butadienes) levels off for the G1 and G2 polymers. Additionally, the ratio of the radius of gyration in solution (Rg) to the hydrodynamic radius (Rb) of the molecules decreases from RJRb = 1.4 to 0.8 from G1 to G2. For linear polymer chains with a coiled conformation in solution, a ratio RJRb = 1.48-1.50 is expected. For rigid spheres, in comparison, a limiting value RJRb = 0.775 is predicted. 

The effects of side chain architectures on the properties and proton conductivities of graft copolymer membranes for DMFCs were studied by Su et al. [126]. Poly(vinylidene fluoride)-g-poly(styrene sulfonic acid) (PVDF-g-PSSA) copolymers with either linear graft (LG) or arborescent graft (AG) PSSA side chains were prepared. Scheme 6.29 shows the structures of LG and AG polymers. 

Figure 6.3 Release profiles for (a) indomethacin and (b) lidocaine in 0.05M HCl in the free state ( ) and from GlPS- ra/ -P2VP copolymer ( ). Mt is the cumulative mass released at time t, and Mgq is the mass released at equilibrium. (Reprinted from Polymer, 49, G.N. Njikang, M. Gauthier and J. Li, Sustained release properties of arborescent polystyrene-grq/it-poly (2-vinylpyridine) copolymers, 5474-5481, 2008, with permission from Elsevier.)...

Yun, S., Briber, R.M., Kee, R.A., and Gauthier, M. (2003) SmaU-angle neutron scattering of arborescent polystyrene-grayt-poly(2-vinylpyridine) copolymers. Polymer, 44,6579-6787. 

Njikang, G., Gauthier, M., and Li, J. (2008c) Arborescent polystyrene-grq -poly(2-vinylpyridine) copolymers as unimolecular micelles. Solubilization studies. Polymer, 49,1276-1284. 

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