Poly(α,l-glutamate)s carrying C8, C10, and C12 fluorinated side chains were synthesized by polymerization of the corresponding amino acid N-carboxyanhydrides. Contact angle measurements with water were used to assess the effects of fluorination on the surface energies of films of the resulting polypeptides. The wettability of the polymers was found to decrease with increasing fluorine content, as expected. A remarkably high contact angle (121°) was measured for the homopolymer carrying C12 fluorinated side chains, indicating a surface consisting of closely packed trifluoromethyl groups. Side chain crystallization, consistent with the formation of such a surface, was suggested by the results of X-ray diffraction and calorimetric measurements.

D,L-Trifluoroalanine IV-carboxy anhydride (d,l-TFANCA) was synthesized by phosgenation of 3,3,3-D,L-trifluoroalanine in tetrahydrofuran.nuclear magnetic resonance and infrared spectra indicate that the electron withdrawing trifluoromethyl group in the a position increases the acidity of the amide proton and the electrophilicity of the carbonyl groups of the anhydride. D.L-TFANCA was polymerized with aniline, thiophenol, or triethylamine as initiator. Time of flight matrix assisted laser desorption mass spectrometry was used to determine the absolute molecular weights and molecular weight distributions of the resulting polypeptides. Knowledge of the exact molecular weight confirmed the structural integrity of the products and gave insight into the mechanism of polymerization. d,l-TFANCA was also copolymerized with 7-benzylL-glutamate NCA. Incorporation of 20 mol % D,L-trifluoroalanine into poly ( -benzyl L-glutamate) leads to a marked decrease in the surface energy of the polymer, as determined by contact angle measurements.

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