Design and synthesis of water-stable aliphatic polycarbodiimides that hydrolyze under controlled catalytic conditions

PMSE 302

Thanasis Karapanayiotis, tk306@cam.ac.uk, Department of Chemistry, University of Cambridge, Lensfield Rd, Cambridge, CB2 1EW, United Kingdom, Stephen C. Moratti, scm1001@cam.ac.uk, Melville Laboratory for Polymer Synthesis, University of Cambridge, Department of Chemistry, Lensfield Road, Cambridge, CB2 1EW, United Kingdom, and Andrew B. Holmes, aholmes@unimelb.edu.au, Bio21 Institute, Department of Chemistry, University of Melbourne, Parkville, South Kensington, Melbourne, Australia.
The synthesis of an organic polymer film that reacts with water on activation with a suitable catalyst is presented. Optimum conditions for the phospholene-catalyzed polycondensation of trans-1,4-cyclohexylene diisocyanate and isophorone diisocyanate, in a chlorobenzene/1,2,4-trichlorobenzene (1:1) solvent mixture, afforded the desired high-load polycarbodiimide in near-quantitative yield. The stability of this material over a 24 hour period at 100% RH was excellent; even when the spin-coated polymer was dipped in water for up to 4 days there was no evidence of urea carbonyl groups. When blended with 10 or 5% (w/w) 2-sulfobenzoic acid cyclic anhydride, however, hydrolysis readily occurred to afford a polyurea. When 2.5% (w/w) acid was employed the rate of carbodiimide hydrolysis was significantly reduced and the extent of reaction did not reach values beyond 65%, as deduced by transmission IR spectroscopy. Similar experiments were carried out with ROMP-generated oligomeric carbodiimides, which reacted with as little as 2% (w/w) catalyst.

 

Joint PMSE/POLY Poster Session
6:00 PM-8:00 PM, Tuesday, 12 September 2006 Moscone Center -- Hall D, Poster

Sci-Mix
8:00 PM-10:00 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Sci-Mix

Division of Polymeric Materials: Science & Engineering

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006