Nanostructurated Block Copolymers: Order-Order and Order-Disorder Transitions in Model Poly(Butadiene-b-Dimethylsiloxane)s

L.R. GÓMEZ; D.A. VEGA; M.D. NINAGO; A.E. CIOLINO; E.M. VALLÉS; M.A. VILLAR

Santiago de Chile, Chile

Conferencia; 10th International Conference on Frontiers of Polymers and Advanced Materials; 2009

Universidad de Chile

In this work, we would like to present the morphological and rheological characterization of model butadiene-dimethylsiloxane block copolymers (PB-b-PDMS). These model block copolymers were obtained by anionic polymerization (high vacuum techniques) using 1,3-butadiene and hexamethyl(ciclotrisiloxane) monomers, sec-butyl lithium as initiator, and sequential addition. The SAXS analysis for a selected sample, which reveals the existence of order-order and order-disorder transitions is shown in Fig. 1. At room temperature, the PB-b-PDMS copolymer presents SAXS peaks characteristics of hexagonally packed cylinders. As the temperature increased above 50 °C a transition from hexagonally packed cylinders to body centered cubic packing (bcc) can be detected . The thermo-reversible transitions observed for this PB-b-PDMS indicates that by choosing proper monomer quantities, the resulting block copolymer would have sufficient mobility to reach their equilibrium morphologies. These findings would open the door for the development of a new group of nano-structurated thermoplastic elastomers.