Novel thermoplastic elastomers. II. Properties of star-block copolymers of PSt-b-PIB arms emanating from cyclosiloxane cores †

摘要: Select mechanical, thermal, and rheological properties of star-blocks consisting 5–21 polystyrene-b-polyisobutylene (PSt-b-PIB) arms radiating from cyclosiloxane cores are described. The tensile products containing 23–41 wt % PSt substantially higher (9.6–23.8 MPa) than those linear triblocks comparable arm molecular weights compositions over the 25–85°C temperature range. mechanical seem to be much less sensitive diblock contamination triblock thermoplastic elastomers similar hard/soft segment composition. strength increases by increasing number (Nw,arm) reaches a plateau in Nw,arm = 5–10 Star-blocks exhibit strengths with lower segmental Mn triblocks. Solvent cast copolymers compression molded products; however, show no significant property differences between samples. dynamic melt viscosities compositions, which is consistent star's unique microarchitecture should lead improved overall processibility. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Chem 37: 815–824,