The Effect of Regio-Chemistry and Functionality On the Separation of the Stereo-Isomers of Nano-Structured Chemicals

The molecular architecture of thermosets, polymers and oligomers has a major impact on their physical properties, including their melting temperature and their glass transition temperature. These physical properties impact the processibility of thermoplastics and thermosets.  Condensation polymerized aromatic thermoplastics such as polyimides, polyaramides, polysulfides, and polyetherketones have excellent material properties, but are difficult to process because of their poor solubility and high thermal transitions. One approach to make these materials more processible, while retaining their excellent properties, is by altering the constitutional isomeric state of a comonomer. To that end, para-and meta- isomers of difunctional phenylethynylphthalimide POSS were synthesized. These isomers were further separated to form cis- and trans- isomers. It was found that the crystallization kinetics is strongly effected by the mixing of cis- and trans- isomers. However, curing kinetics as well as thermal stability is less influenced by the para- and meta- isomers of phenylethynylphthalimide POSS.