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The conformational behavior of the synthetic peptide, Boc-Gly-Val-Gly-Gly-Leu-OMe, containing the X-Gly-Gly and Gly-Gly-X (X = Val or Leu) repeating sequences and constituting a fragment of elastin was investigated by molecular mechanics and molecular dynamics (MD) simulation. The results suggest that, irrespective of the approximations used, the molecule shows a manifold of low energy conformations characterized by gamma-turns and type II beta-turns. Furthermore, MD simulations point out a conformational floppiness due to very low barriers between different conformations. Experimental CD measurements in a virtually apolar medium (dioxane--epsilon = 2.209), which better mimics the vacuum conditions of the simulation, support the theoretical results. The general emerging picture, indicating the molecule as characterized by a combination of flexibility with conformational preferences, is in agreement with previous experimental findings and enriches of new aspects the description of the microscopic behavior of this molecule suggesting more detailed interpretation of previous data.

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The thermal behavior and overall isothermal crystallization kinetics of a series of organophilic modified montmorillonite–poly(ϵ‐caprolactone) nanocomposites were investigated. In general, the thermal behavior was influenced more by the type of dispersion than by the clay content. For nanocomposites in which silicate platelets were predominantly dispersed in the polymer matrix to give exfoliated structures, the thermal properties were improved with respect to those of neat poly(ϵ‐caprolactone), whereas in those cases in which simply intercalated structures were attained, the thermal properties regularly decayed as the clay content increased. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1321–1332, 2004

Lignin powder, obtained from an abundant and low-cost source, straw, through a low-environmentalimpact process, steam explosion, was used for the preparation of blends with a biodegradable polyester, poly (e-caprolactone) (PCL), with an innovative technique, highenergy ball milling. Lignin strongly stabilized PCL against UV radiation. The modulus of the blends increased with the addition of lignin; nevertheless, the elongation at breaking decreased. Through thermal characterization (differential scanning calorimetry and dynamic mechanical analysis), lignin and PCL were found to be immiscible.