Some aspects of the orientational order distribution of flexible chains in a diblock mesophase.

The segmental motions of flexible chains in the lamellar structure of a strongly segregated poly(styrene)-poly(dimethylsiloxane) (PS-PDMS) diblock were investigated over a time scale of a few tens of microseconds. (2)H NMR experiments were performed on the PDMS block, selectively perdeuterated. Transverse relaxation measurements show that the main part of the PDMS repeat units display anisotropic reorientational motions within the diblock lamellae and such a segmental ordering essentially results from interchain steric repulsions.

Polymeric micelles and nanoparticles from block and statistical poly((RS)-3,3-dimethylmalic acid) derivatives: preparation and characterization.

Amphiphilic and biodegradable micelles and nanoparticles designed as potential drug carriers were prepared from biodegradable statistical and block copolyesters obtained by a living anionic ring-opening process. These novel materials display amphiphilic properties arising from the joint presence of hydrophilic poly((RS)-3,3-dimethylmalic acid) and hydrophobic poly(hexyl (RS)-3,3-dimethylmalate) segments. Micelles obtained from a well-defined block copolymer have been characterized by their critical aggregation concentration, and nanoparticles derived from statistical copolymer have been analyzed by transmission electron microscopy (TEM).

Fourier transform infrared spectroscopy for screening and quantifying production of PHAs by Pseudomonas grown on sodium octanoate.

Poly(hydroxyalkanoates) PHAs are synthesized by many bacteria as inclusion bodies and their biodegradability and structural diversity have been studied with a view to their potential application as biodegradable materials. A method based on FT-IR was developed to carry out rapid qualitative and quantitative analysis of PHAs in Pseudomonas, when they were grown on sodium octanoate. Using absorbance of the ester band of PHAs, a rapid method was reported to distinguish PHB and PHO and to determine polymer content in intact bacteria.

Polymerization of propyl malolactonate in the presence of Candida rugosa lipase.

To gain better insight into mechanistic features of enzyme-catalyzed malolactonate polymerization, reactions with propyl malolactonate were analyzed while varying enzyme concentration, reaction media composition, and reaction temperature. Monomer conversion and product molecular weights were characterized by (1)H NMR and MALDI-TOF MS, respectively. A high extent of thermal polymerization of propyl malolactonate was observed, while the polymer chain length in all reactions was controlled by the elimination of alpha-hydrogen from propyl malolactonate with formation of a new initiator and the new chains.