
76 HIGH PERFORMANCE POLYMERS
the crystallinity changes from semi-crystalline via
liquid crystalline to completely amorphous. Also,
the photophysical properties of the polymers are
influenced by the side chains.
When casted inhydrophobic or hydrophilicsolvents
the polymers exhibit twoglass transition temperatures.
This can be readily explained by differences in the
microstructure [22].
Hydrophilic branched oligo(ethylene glycol)-
substituted PPV derivatives, poly(2,5-bis(1,3-bis(tri-
ethoxymethoxy)propan-2-yloxy)-1,4-phenyleneviny-
lene) and poly(2-methoxy-5-(1,3-bis(triethoxymeth-
oxy)propan-2-yloxy)-1,4-phenylenevinylene), have
been described [23]. The