Polymer Science Faculty Research

Title

SYNTHESIS AND THERMOTROPIC BEHAVIOR OF POLYNORBORNENES WITH LATERALLY ATTACHED 2, 5-BIS [(4'- N-ALKYLTHIOBENZOYL) OXY] BENZYL MESOGENS

Document Type

Article

Publication Date

2007

Abstract

roduction Supramolecular chemistry investigates entities generated via intermolecular, non-covalent bonding such as hydrogen bonding, electrondonor-acceptor (EDA) interactions and metal ion coordination, which can be used to generate polymolecular assemblies.i In spite of maturity of the field of low molar mass liquid crystals (LMMLCs) and side-chain liquid crystalline polymers (SCLCPs) in electro-optical displays, few concepts have been developed for converting the type of mesophases exhibited by a given chemical structure. The most significant transformation is from nematic to smectic mesophases, and vice versa. Induction of a smectic mesophase in laterally attached SCLCPs (Scheme 1) is particularly challenging since this molecular architecture generally precludes smectic mesomorphism. For example, polynorbornenes with laterally attached 2,5-bis[(4’-nalkoxybenzoyl)oxy]benzyl mesogens exhibit only a nematic mesophase.ii Since there is greater interaction between the mesogens in a smectic vs. nematic alignment, we are attempting to induce smectic layering in poly{5- [[[2’,5’-bis[4”-n-alkoxybenzoyl)oxy]benzyl ]carbonyl]bicylclo[2.2.1]heptene- 2-ene}s2 via EDA interactions by (co)polymerization of an electron-rich thioether norbornene analogue and an electron-poor sulfone norbornene analogue (Scheme 2) by ring-opening metathesis copolymerization. However, we must first understand the effect of changing the ether substituents in the model compounds, monomers and polymers, to both thioether and sulfone functionalities. This paper reports the synthesis and thermotropic behavior of the thioether model compounds and homopolymers.

Publication Title

Polymer Preprints

Volume

48

Issue

1

First Page

1001