TIT# Synthesis and Properties of some $\epsilon$-Caprolactone-Based Di- and
     Triblock Polymers by Anionic Polymerization
AUT# Buzdugan, Emil; Ghioca, Paul; Stribeck, Norbert; Beckman, Eric J.;
     Serban, Sever;
SOU# Macromol. Mater. Eng. (2001), 286, 497-505
LOC# xv062
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ABS# Block copolymers containing $\epsilon$-caprolactone blocks were
     synthesized. Mechanical properties as a function of chemical composition
     and domain structure as a function of elongation were studied. Based
     on previous optimal conditions determination by factorial design of
     experiments of $\epsilon$-caprolactone anionic polymerization,
     poly(styrene-block-$\epsilon$-caprolactone), poly(isoprene-block-
     $\epsilon$-caprolactone), poly(styrene-block-butadiene-block-
     $\epsilon$-caprolactone) (SBCL), and poly(styrene-block-isoprene-block-
     $\epsilon$-caprolactone) (SICL) with different compositions were
     synthesized and characterized by GPC and DSC. Both the SICL and SBCL
     materials are thermoplastic elastomers, from which spin-cast films were
     prepared. Their mechanical properties were determined, small-angle
     X-ray scattering (SAXS) measurements were carried out during straining,
     and dynamic mechanical analysis (DMA) was performed. All diblock polymers
     separate into a two-phase structure, but the melting point of crystalline
     poly($\epsilon$-caprolactone) domains in the block copolymer is higher
     than in the case of the homopolymer. According to DMA data some of the
     SICL and SBCL materials are three-phase systems, but others are only
     two-phase systems. The two-phase materials show a considerable depression
     of the composite hard domain glass transition and, consequently, turn out
     to be very soft. It appears peculiar that the transition from three-phase
     to two-phase material is accomplished by decreasing soft block length.
     For the soft material SAXS exhibits a lamellar stack nanoscale structure
     and several reflections of colloidal crystals. As a function of increasing
     elongation the crystal reflections broaden, whereas lamellar stacks rotate
     as a whole.