Structural effects in poly(3-alkylthiophene)s on the exposition to poor solvent

The exposure to pentane vapour of poly(3-alkylthiophene)s with different alkyl chains produces a modification in the optical properties of the thin films. The treatment induces a red-shift of the electronic absorption maximum and the appearance of vibronic structure in the UV spectra. We have followed these changes with IR and Raman spectroscopies to monitor the modification of the backbone conjugation, and with X-ray diffraction to evidence the structural order of the chains.     

Tailor-made polymers and copolymers from aziridines and 1,3-oxacyclanes

Telechelic poly(tert-butylaziridine)s (polyTBA) and poly(1,3,6-trioxocane)s (polyTOC) and macromonomers were synthesized mainly by living cationic polymerization. Both, molecular weight and end-functionality distributions of polyTOC oligomers and polymers were studied using a combination of HPLC under “critical conditions”, gradient HPLC and SEC with double detection following a preparative HPLC fractionation. Monofunctional and bifunctional polyTBA with various end-groups were synthesized by the end-capping method. Several modification reactions were examined for terminal transformation of polyTBA and polyTOC hydroxy-telechelics into mono- and bifunctional vinyl ether macromonomers. Various tailor-made polymers based on uniform size telechelics and macromonomers were prepared using: 1. polymer-polymer coupling to produce block copolymers; 2. polyaddition of amino-functionalized telechelics to bisacrylamides; 3. addition of amino-polyTBA to polydienes; 4. synthesis of graft copolymers with well-defined graft component and networks.     

Influence of “controlled processing conditions” on the solidification of iPP,PET and PA6

In this work reliable experimental data for three semicrystalline polymers (iPP, PA6, PET) crystallised under pressure and high cooling rates are supplied. These results were achieved on the basis of a model experiment where drastic “controlled” solidification conditions are applied. The final objective was to quantify the effect of two typical operating conditions (pressure and cooling rate) on the final properties and morphology of the obtained product. The influence of processing conditions on some macroscopically relevant properties, such as density and micro hardness is stressed, together with the influence of processing conditions on the product morphology, investigated by means of Wide Angle X-Ray Scattering (WAXS). Results on the iPP samples display a decrease of density and micro hardness, due to the pressure increase, in a wide range of cooling rates (from 0.01 to 20°C/s). PET samples exhibit an opposite behaviour with density and micro hardness increasing at higher pressures in the whole range of cooling rates investigated. PA6 samples behave similarly to PET displaying a less significant increase of density and micro hardness with pressure than PET samples.