A problem encountered in
ABC triblock copolymers with short end blocks (i. e.
end blocks forming spheres or cylinders) is the usually
insufficient degree of incompatibility between A and C,
wAC.NAC (NAC is the degree of polymerization of the Aand
C-block and wAC is the segmental interaction parameter
between the two species) [3,4]. Semicrystalline end
blocks offer a way to achieve segregated end blocks at
rather lowmolec ular weights, since crystallization is a
strong driving force for microphase separation. Investigations
on polyethylene-block-poly(ethylene-alt-propylene)
(PE-b-PEP) diblock copolymers showthat even for
lowmo lecular weights a microphase separated structure
is obtained due to crystallization induced microphase
separation [5–7]. Furthermore, this system exhibits a
small value for the segmental interaction parameter w of
0.007 at 120 C (above the melting point of PE) resulting
in a homogeneous melt in a wide composition range
which is advantageous in view of processing [8].