An approach to molecular composites
Abstract
One objective was to demonstrate that a nematogen can be made to exhibit a cholesteric phase by the incorporation of chiral centers into the polymer chain. The Yamazaki reaction was used to introduce 3 mole percent of chiral L-valine into poly(p-benzamide). This was shown to form a lyotropic cholesteric phase by circular dichroism and the induced circular dichroism of an achiral dye. A disadvantage of the use of lyotropic mesomorphism was that few solvents were available and the production costs were high. The early lattice model treatment of Flory indicated that a highly extended molecular conformation was essential to the formation of this type of mesophase. It has been demonstrated that the melting point depression of a crystalline polymer by this type of mesophase will be quite small unless the polymer-solvent interaction is very favorable. This implies that the polymer solubility will only be sufficient for the formation of a lyotropic mesaphase for those few polymer-solvent systems in which the interactions were very favorable. It was found that the Yamazaki phosphorylation reaction could be made to yield aromatic polyamides of higher inherent viscosity by using a monomer having pre-formed amide linkages. It is believed that this occurs due to reduction in the byproducts of the polymerization.
- Publication:
-
Final Report
- Pub Date:
- December 1982
- Bibcode:
- 1982duke.rept.....K
- Keywords:
-
- Dichroism;
- Fibers;
- Molecular Chains;
- Polymer Chemistry;
- Polymer Physics;
- Copolymers;
- Crystallinity;
- Fiber Orientation;
- Phosphorylation;
- Polyamide Resins;
- Polymerization;
- Solid Phases;
- Atomic and Molecular Physics