Preparation of single-molecule particles of water-soluble polymers

Single-molecule particles of a series of water-soluble polymers are prepare d via a spray dryer from dilute polymer aqueous solutions. Two of these pol ymers, poly(acrylic acid) and polyacrylamide, are used as examples to illus trate the preparation and identification of single-chain molecules. Scannin g electron microscopy shows that these dried particles possess diameters ra nging from 1 to 4 mum. Transmission electron microscopy reveals that each p article consists of numerous distinctly separated small particles with a ra dius of a few nanometers. Each of these particles consists of a single-chai n molecule, a conclusion based on calculations of volume involving the poly mer molecular weight. This method lends itself to the preparation of single -molecule particles of water-soluble polymers in mass quantity, which may p rovide a gateway to studying the chemistry and physics of polymer single-mo lecules in a condensed state. (C) 2001 Elsevier Science Ltd. All rights res erved.