Molecularly Designed Auxetic Polymers: A Remarkable New Class of Materials

摘要

During the first year of the grant period, the key personnel were brought on board-Dr. Bertrand Guichard from Paris and Puwei Lin a new Phd student at USM. The target monomers were selected and synthetic work was begun. Two general synthetic plans were followed: one to prepare in 'inverted honeycomb/reentrant cell' macrocycle and the other to prepare monomers for a main chain liquid crystalline polymer. The first of these, the macrocycle, was sought to examine the idea that in-plane stretching deformation of such a structure could lead to a negative Poisson ratio material. In turn a network of such reentrant cells could produce-by a flexing or hinging motion- a polymeric negative Poisson ratio material. Synthetic work along these lines, although interesting in its own right, did not produce the desired macrocyle. Instead, there was premature macrocycle formation early in the synthetic route which- although producing intriguing new macrocycles- did not advance this area of the project. After numerous attempts at this target, it was decided to concentrate exclusively on the second approach- the main chain liquid crystalline polymer approach.