Roger Pétiaud

Organo-metallic complex characterization formed when liquid epoxy-diamine mixtures are applied onto metallic substrates

The interfacial reactivity between metal (titanium, aluminum and gold) and epoxy-diamine prepolymer has been studied. When epoxy-diamine mixtures are applied onto gold-coated substrates, coating properties are the same as epoxy-diamine bulk ones. However when they are applied on metallic substrates (Ti and Al) and cured, an interphase, having chemical, physical and mechanical properties quite different to polymer bulk ones is formed. Nuclear magnetic resonance (NMR), FTIR, polarized optical microscopy (POM), and inductively coupled plasma spectroscopy (ICP) analyses suggest that diamine monomers chemically react and dissolve the hydrated metallic oxide layer. Metallic ions diffuse through the liquid organic layer to form a organo-metallic complex by coordination binding resulting from the electron-rich nitrogen atom of amine groups donating its lone pair to the electron-deficient metallic center.

Functional polymers supported on porous silica. I : Grafting active precursors onto porous silica

Abstract A set of porous silica has been grafted with trialkoxysilane coupling agents carrying either a γ-propyl methacryloyl group, a γ-propyl thiol or a γ-propyl amine group. The grafts have been characterized by diffuse reflectance Fourier transform infrared spectroscopy and 29Si and 13C cross-polarization magic-angle-spinning nuclear magnetic resonance; the grafting yields were estimated from elemental analysis. The grafted amine was further reacted with azobiscyanovaleric acid. The grafted materials are to be used as co-monomer, transfer agent or initiator for a further grafting of a functional polymer via a radical polymerization.

Properties of PETG/EVA blends: 2. Study of reactive compatibilization by n.m.r. spectroscopy and linear viscoelastic properties

Abstract The reaction product of both methylbenzoate and dimethylphthalate with dibutyltin oxide was determined to be an 1-alkoxy-3-acyloxy distannoxane by multinuclear n.m.r. spectroscopy (1H, 13C and 119Sn) in solution. Dibutyltin oxide promotes ester interchange reactions. It was used to compatibilize the immiscible blend of polyethylene terephthalate glycol (PETG) with the ethylene vinyl acetate (EVA) copolymer. The linear viscoelastic properties of the compatibilized blend were determined and analysed in light of the n.m.r. results.

Existence of an intradimeric rearrangement in monofunctional tetrabutyldistannoxanes [Bu4Sn2X2O]2 probed by multinuclear NMR spectroscopy in solution and in solid state

Abstract A set of 1-D and 2-D, 13 C- and 119 Sn-NMR experiments—both in solution and in the solid state—exhibit a common peculiarity of the monofunctional tetrabutyldistannoxanes of general formulae R 4 Sn 2 X 2 O in comparison with the no problematic NMR data of difunctional tetrabutyldistannoxanes R 4 Sn 2 XYO. Relying on the support of these observations, the existence of a dynamic process is evidenced in solution. This process, rapid and equilibrated at ambient temperature, is shown to be frozen both in solution at 188 K and in the solid state. A mechanism of intramolecular rearrangement of the distannoxane dimeric form is discussed on the basis of modelisation of the movements required. It accounts for all spectroscopic observations and is not expected to occur with the dimer form of the difunctional distannoxanes (X≠Y).

Multinuclear NMR Characterization of Co-cross-linking of Ethylene-co-vinylacetate and Ethylene-co-methylacrylate Polymer Blends in the Presence of Dibutyltin Oxide

Abstract The co-cross-linking reaction of ethylene-co-vinylacetate (EVA) and ethylene-co-methylacrylate (EMA) polymer blends in the presence of dibutyltin oxide in the molten state is an interchain redistributive transesterification (ester-ester interchange reaction). It is shown with model esters, namely n-octyl acetate (1) and methyl nonanoate (2) in solution, that the efficientcatalytic species are 1,3-acyl, alkoxy distannoxane from the reaction of esters with dibutyltin oxide. An intermolecular dimeric rearrangement between acyl and alkoxy dimeric distannoxanes from (1) and (2) esters occurs at ambient temperature without ligand exchange. Ligand exchange on tin atoms by reactions between free ester (1) and dimeric distannoxane occurs at higher temperature at both acyloxy and alkoxy tin sites. Reactions are characterized by multinuclear NMR spectroscopy (1H, 13C, 119Sn). Tetra acyloxy or tetra alkoxy distannoxanes are also efficientcatalysts for this redistributive transesterification.

Copolyimides with trifluoromethyl or methoxy substituents. NMR characterization

Abstract In the first stage, a series of aromatic diamine compounds such as 2-methoxy-5,4′-diaminodiphenyl ether (ODAOMe) and 2-trifluomethyl-4,4′-diaminodiphenyl ether (ODACF 3 ) were synthesized. These aromatic diamines and 4,4′-diaminodiphenyl ether (ODA) were then used to prepare copolyimides with 4,4′-oxydiphthalic anhydride (ODPA) and bicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA). Both chemical composition and the arrangements of repetitive units were characterized by 1 H and 19 F NMR. It was shown that solubility and thermal stability are related to the BCDA fraction in the copolymers and to the chemical structure of the diamine.

A 1H and 13C n.m.r. study of the products from direct polyesterification of ethylene glycol and terephthalic acid

Abstract Low molecular weight samples of poly(ethylene terephthalate), obtained by direct bulk polyesterification of terephthalic acid and ethylene glycol, were studied by 1H and 13C n.m.r. It was possible to determine degrees of conversions of acid and alcohol groups, distributions of free, monoesterified and diesterified terephthalic acid and ethylene glycol and to identify the dimer, trimer and tetramer. Side reactions were also studied.

Mechanisms of the bulk copolyesterification of azelaic acid, o-phthalic anhydride and trimethylolpropane studied by 13C nuclear magnetic resonance

Abstract Polyesterifications in bulk of trimethylolpropane (T) with azelaic acid (Z) and o -phthalic anhydride (P) and copolyesterification of a (Z + P + T) ternary mixture have been studied by 13 C nuclear magnetic resonance (n.m.r.) before and after gelation. It has been found that Z is more able than P to give covalent gels. 13 C n.m.r. allows quantitative determinations of the conversions of acid functions of Z and P and alcohol functions of T as well as the distributions of monoester and diester of P and those of free, mono-, di- and triesterified T. In all cases, the actual critical conversions are larger than the theoretical ones calculated due to the Flory-Stockmeyer statistics because (i) 3–5% of free T and P are trapped and (ii) the two acid functions of P or Z and the three alcohol functions of T do not have the same reactivities. For the ternary system, four types of T triesters have been identified and quantitatively determined, and finally, reticulation should only occur if more than one-third of T are triesterified. In the copolyesterification in bulk of the (0.5Z + 0.5P + 0.8T) mixture, the distributions of Z and P on the mono-, di- and triesterified T follow Bernoullian statistics.

Reaction of dibutyltin oxide with amides in presence of traces of water: multinuclear NMR study and mechanism

Abstract The product of the reaction of primary and secondary amides with dibutyltin oxide is shown to be a dimeric 1,3-diacyloxytetrabutyldistannoxane. The reaction was studied in bulk with model amides at 180°C, avoiding perfect anhydrous conditions, in view to be transposable to transamidification with reactive extrusion process. The formation of an intermediate compound of the type 1-acyloxy-3-alkylaminotetrabutyldistannoxane is pointed out. With an excess of amide, the presence of water leads to the dimeric 1,3-diacyloxytetrabutyldistannoxane. Without an excess of amide, the hydrolysis of this intermediate leads to a more complex tetrastannoxane structure associated in a more or less perfect ladder-like structure including partially hydrolyzed and condensed forms of the distannoxane. The dimeric 1-acyloxy-3-alkoxytetrabutyldistannoxanes resulting from the reaction of esters with dibutyltin oxide are shown to give a similar stannoxane structure after hydrolysis. All the products were characterized in solution by 1 H-, 13 C- and 119 Sn-NMR spectroscopy. On the basis of the spectroscopic analysis, a mechanism of the reaction is proposed and discussed.

Bulk copolyesterification of azelaic acid, o-phthalic anhydride and trimethylolpropane. Statistical distributions of acid branches on triol units studied by 13C n.m.r.

Abstract The mechanisms of tri-dimensional polyesterifications in bulk at 180°C of ternary mixtures of o-phthalic anhydride (P) + azelaic acid (Z) + trimethylolpropane (T), as well as the distributions of acid branches on the potential crosslinking T units, have been studied by liquid 13C n.m.r. before (sol) and after (gel) gelation. The critical time for gelation is found to decrease when Z increases, and in all cases the actual critical conversions are larger than those calculated by the classical statistical Flory-Stockmayer relation. Transesterification reactions actually occur during polyesterification. Before as well as after gelation, the distributions of P and Z in diesters and triesters of T follow two slightly different Bernouillian statistics because of the better reactivity of Z than P.