title: Vesicles made of PS-PI cyclic diblock copolymers: in situ freeze-drying cryo-TEM and dynamic light scattering experiments.
abstract: We have studied the morphology of self-assembled micelles made of linear and cyclic poly(styrene-b-isoprene) PS-b-PI block copolymers dispersed in selective solvents of the PI block (n-heptane, n-decane). Up to a copolymer concentration of 5 mg mL(-1), the micelles made from linear block copolymer chains adopt a spherical shape. Those arising from cyclic copolymer chains having exactly the same molar mass and volume fraction self-assemble into (i) planar sunflower-shaped particles at low concentration (c < 0.1 mg mL(-1)), (ii) giant wormlike micelles at intermediate concentration (0.1 mg mL(-1) < c < 2 mg mL(-1)) and (iii) vesicles at higher concentration (2 mg mL(-1) < c < 5 mg mL(-1)). Those results were obtained using dynamic light scattering and in situ freeze-drying cryo-transmission electron microscopy. In this contribution, we discuss the effects of concentration and temperature on the morphology of the self-assembled particles made from both linear and cyclic PS-PI copolymers, and highlight the surprising vesicle formation in cyclic block copolymer solutions.
authors.affiliation: Laboratoire de Chimie des Polymères Organiques, LCPO-CNRS, UMR 5629, ENSCPB and Bordeaux University I, Pessac, France.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Putauz
authors.forename: Edson
authors.initials: E
authors.lastname: Minatti
authors.forename: Christelle
authors.initials: C
authors.lastname: Lefebvre
authors.forename: Redouane
authors.initials: R
authors.lastname: Borsali
authors.forename: Michel
authors.initials: M
authors.lastname: Schappacher
authors.forename: Alain
authors.initials: A
authors.lastname: Deffieux