Haloacetaldehyde polymers and macromolecular asymmetry

Polyhaloaldehydes play a special role in aldehyde polymerization. The most prominent trichloroacetaldehyde polymer, polytrichloroacetaldehyde, opened the door to new concepts in polymer chemistry: first, cryotachensic polymer ization, the separation of the initiation step from the propagation steps w ith the ceiling temperature principle for the fabrication of insoluble and infusible polymers, and second, the concept of macromolecular asymmetry and stereospecific and conformationally specific polymerization. Trichloroacet aldhyde could be readily polymerized with a wide range of anionic land also some cationic) initiators. When the anionic polymerization was initiated w ith chiral anions, it gave polychloral of one helix sense. To understand th e genesis of the polymerization, the oligomerization was investigated to le arn how the stereochemistry of the polymerization was established, also in chiral form. All 10 fluoro-, chloro-, and bromo-substituted trihaloacetalde hydes were synthesized as necessary and polymerized, and the polymers were investigated. (C) 2000 John Wiley si Sons, Inc.