Poly(amide ester)s from 2,6-pyridinedicarboxylic acid and ethanolamine derivatives: identification of macrocycles by matrix-assisted laser desorption/ionization mass spectrometry

The influence of the polycondensation pathway and aminoalcohol structure was investigated in the synthesis of poly(amide ester)s by polytransesterification from ethyl pyridine-2,6-dicarboxylate and 2-amino-2-methylpropan-1-ol or the corresponding bis(amide alcohol), or by polycondensation from the diacid dichloride. Both linear and cyclic structures were identified by steric exclusion chromatography (SEC) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). Transesterification led to cyclic oligomers (macrocycles) with 2-14 pyridine moities in the ring whereas polycondensation from the diacid dichloride gave low molecular weight polymers (Mn = 1800) and macrocycles.     

Polymérisation de monomères organiques dans des plasmas froids-2: Polymérisation de monomères acryliques en présence d'amorceurs

The polymerization of low vapour pressure acrylic monomers may be carried out under partial vacuum in reaction vessels under electric discharges. Added radical initiators lead to increase of reaction rate as well as the maximum conversion. Various experimental conditions are involved viz. nature of the initiator and ambient gas, time and power of radiation, film thickness. The mechanism shows similarities with polymerization under u.v. radiation. The initiator decomposition is mainly due to the wave emission from the plasma ambient gas. The monomer used is trimethylolpropane triacrylate.     

Modification chimique des polyalcadienes par les composes du type cx3poz2-I: Modification des polybutadienes-1,2 par le dichlorure de trichloromethylphosphonyle

The cupric chloride catalysed radical addition of trichloromethylphosphonyl dichloride (CCI₃POCI₂) (1) to 1,2-polybutadi6ne (M_n < 10,000) is described. The influences of various parameters (reaction temperature, reagent concentrations, catalyst concentration, nature and concentration of solvents, reaction time) on the yield have been examined. Polymers having dichloromethylphosphonyldichloride groups are obtained, but cyclization and cross-linking reactions compete with the addition of (1) to carbon-carbon double bonds. The fire resistance of these modified polybutadienes has been tested: the products are non-flammable and their use as fire proofing additives for polybutadiene is investigated.     

Nouveaux Élastomères de polyuréthanes dérivés d'aminoacides

Synthesis and characterization of new polyurethane elastomers with rigid blocks derived from aminoacids have been achieved by polycondensation using poly(tetramethylene oxide) (PTMO) as a soft segment. Aminotelechelic oligopeptides or pseudopeptides were used in the hard block, eventually in association with lysine diisocyanate (ethyl 2, 6-diisocyanatohexanoate, LDI). Physicochemical characteristics of the so obtained materials, especially good filmmaking properties, allow their use as biomaterials of reduced toxicity.     

Application of solid-state NMR (13C and 29Si CP/MAS NMR) spectroscopy to the characterization of alkenyltrialkoxysilane and trialkoxysilyl-terminated polyisoprene grafting onto silica microparticles

The solid-state Nuclear Magnetic Resonance (NMR) was used to characterize surfaces of silica gels chemically modified by alkenyltrialkoxysilanes and trialkoxysilyl terminated 1,4-polyisoprenes. The formation of covalent bonds created between alkoxy functional groups from alkenyltrialkoxysilane or trialkoxysilyl-terminated 1,4-polyisoprene and silanol groups on silica was clearly demonstrated by means of ¹³C and ²⁹Si CP/MAS NMR spectroscopy. Quantitative data, including calculation of the grafting yields in relation with the initial silanol concentrations, were also obtained by using solid-state ²⁹Si-NMR leading to a final well-defined characterization of the silica surfaces. A relatively good agreement was noticed between the grafting yields calculated from ²⁹Si-NMR spectra and those determined from other analytical techniques such as Wijs titration or elementary analysis. The reactivity of the various silica silanols towards each coupling agent was clearly characterized and estimated, as were the proportions of the various grafted structures formed at the silica surface. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36 : 437–453, 1998