The goal of this research is to investigate various liquid crystalline epoxy resins (LCERs) and identify the most promising systems to be used as polymer matrices for high performance composites.
LCERs are a relatively new class of thermosetting materials. The liquid crystalline (LC) phase formed upon curing of low molecular weight, multifunctional monomers can be retained by the three dimensional crosslinked networks that form during polymerization. The versatility of traditional epoxy resins, such as good mechanical properties, excellent chemical resistance, and low shrinkage upon curing can be further improved by introducing the LC phase into the networks.
LCERs may be obtained using monomers with rigid aromatic groups with functional end groups that facilitate crosslinking reactions. Fully cured LCERs exhibit a semicrystalline structure with individual LC domains distributed in an amorphous matrix. The ordered and rigid structure of LC domains can bring desirable thermomechanical characteristics such as low coefficient of thermal expansion (CTE) and high glass transition temperature. In addition, the fracture toughness of the resins can be greatly improved due to the presence of LC domains. Another interesting aspect of LCERs is their ability to be oriented under magnetic field. The resulting resins are expected to have substantial reduction in CTE and better thermomechanical properties than the unoriented materials.
Yuzhan Li, Prashanth Badrinarayanan, Michael Kessler