D,L-Trifluoroalanine N-carboxy anhydride (D,L-TFANCA) was synthesized by phosgenation of 3,3,3-D,L-trifluoroalanine in tetrahydrofuran. ^1H 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 γ-benzyl L-glutamate NCA. Incorporation of 20 mol % D,L-trifluorodanine into poly(γ-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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Dessipri et al. (1994) studied this question.