Main chain thermotropic liquid crystal esters, ester-imides, and ester-amides
were prepared from AA, BB, and AB type monomeric materials and were end-capped
with phenylacetylene, phenylmaleimide, or nadimide reactive end-groups. The resulting
reactive end-capped liquid crystal oligomers exhibit a variety of improved and
preferred physical properties. The end-capped liquid crystal oligomers are thermotropic
and have, preferably, molecular weights in the range of approximately 1000-15,000
grams per mole. The end-capped liquid crystal oligomers have broad liquid crystalline
melting ranges and exhibit high melt stability and very low melt viscosities at
accessible temperatures. The end-capped liquid crystal oligomers are stable for
up to an hour in the melt phase. These properties make the end-capped liquid crystal
oligomers highly processable by a variety of melt process shape forming and blending
techniques including film extrusion, fiber spinning, reactive injection molding
(RIM), resin transfer molding (RTM), resin film injection (RFI), powder molding,
pultrusion, injection molding, blow molding, plasma spraying and thermo-forming.
Once processed and shaped, the end-capped liquid crystal oligomers were heated
to further polymerize and form liquid crystalline thermosets (LCT). The fully cured
products are rubbers above their glass transition temperatures. The resulting thermosets
display many properties that are superior to their non-end-capped high molecular
weight analogs.