Solvent induced phenomena in a dendronized linear polymer.

ABSTRACT: The properties of a dendronized linear polymer (DP) in dilute solutions depending on solvent quality and temperature are described. The polymer has a contour length of L_c?=?1,060 nm. The sample of the fourth generation (PG4) was analyzed in the thermodynamically good solvents dioxane, chloroform, and methanol. The wormlike macromolecule has a persistence length l_p?=?7 nm in dioxane and a cross-section radius determined by small angle X-ray scattering (SAXS) of R_{c (SAXS)}?=?2.8 nm. The bulk density of PG4 determined by SAXS was compared with solution density. Evidence for substantial swelling of the cross-section was found. Toluene acts as a thermodynamically poor solvent (? solvent). Above the ? temperature T_? , a strong temperature dependence of the size and the Young's modulus E was observed. Following Odijk, E/k_BT ?1 was found. Below T_? , a regime characterized by unswelling of the wormlike chains was observed. The results suggest that DPs can be described as soft colloid filaments, which are subject to commonly observed interactions in colloidal systems. A phase diagram indicates a regime below T_? in which fluctuations of osmotic pressure inside the filaments result in periodic undulation of the chains. In summary, introducing a dense dendritic shell around the backbone converts conventional polymers into molecular colloids. Figure?

SUBMITTER: Kroeger A 

PROVIDER: S-EPMC3830750 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature