RESUMEN
We study asymmetric block copolymers with the simple diblock AB architecture, in the case where the longer block A is both hydrophobic and "soft", whereas the shorter block B is hydrophilic and "hard". Materials with such a particular combination of physico-chemical and mechanical properties have distinctive advantages, in particular for designing water-compatible adhesive materials. The phase diagram is established, combining NMR and SAXS characterisations of the materials. The swelling with water is monitored through gravimetry and "time-resolved" SAXS. Indications of maintained adhesive properties in a wet environment are given.
RESUMEN
A recombinant esterase from Pseudomonas fluorescens (PFE) was produced from E. coli cultures and the enantioselectivity towards a series of racemic substrates was investigated. PFE exhibited high rate and enantioselectivity in the acylation of alpha-phenyl ethanol with vinyl acetate in toluene (E > 100) and the hydrolysis of the corresponding acetate in phosphate buffer (E = 58). In sharp contrast, extremely low enantioselectivity (E from 1.1 to 7) was found for the acylation of a series of 1,2-O-protected glycerol derivatives and the hydrolysis of 3-phenylbutyric acid methylester. Almost no reaction occurred with alpha-phenyl propanol and its acetate and 2-phenylbutyric acid ethylester.