SURFACE CHARACTERIZATION OF TYROSINE-DERIVED POLYCARBONATES

The surfaces of five biodegradable tyrosine-derived polycarbonates wer e studied using contact angle measurements, ESCA, and static SIMS. The wettability, critical surface tension, and polarity of these polymers decreased with increasing chain length of the pendent alkyl groups. S urface elemental composition, as determined by ESCA, was consistent wi th the stoichiometry of the repeat unit of the polymers. High-resoluti on C1s, O1s, and N1s ESCA spectra also showed results consistent with the different bonding states of these elements in the polymer repeat u nit. In both positive and negative ion spectra, SIMS experiments showe d fragment ions characteristic of the polymer backbone. Fragment ions characteristic of the pendent groups were identified in the negative i on SIMS spectra only, while the positive SIMS spectra provided a chara cteristic fingerprint for each polymer. (C) 1997 John Wiley & Sons, In c.