Shui-Yu Lu

RECENT DEVELOPMENTS IN THE CHEMISTRY OF HALOGEN-FREE FLAME RETARDANT POLYMERS

Abstract An overview of recent developments of the chemistry of halogen-free flame retardant polymers is presented in this paper. The polymers or reactive monomers that are inherently flamed retarding contain P, Si, B, N and other miscellaneous elements. They can be used on their own or added to current bulk commercial polymers to enhance flame retardancy. The synthetic chemistry of these molecules is discussed along with their thermal stabilities and flame-retardant properties.

Microwave-enhanced radiochemistry

The application of microwaves to synthetic organic chemistry is currently experiencing considerable growth. Here we show how the area of radiochemistry, with particular reference to the synthesis of 3H- (or T-), 11C- and 18F-labelled compounds, can benefit. Faster, cleaner, more selective reactions are possible with the formation of much reduced levels of radioactive waste.

Microwave-enhanced aromatic dehalogenation studies: a rapid deuterium-labelling procedure

Rapid (<1 min) and specific deuterium labelling is achieved through the microwave-enhanced dehalogenation of a number of N-4-picolyl-4-halogenobenzamides using deuterated formate as solid deuterium donor and either homogeneous or heterogeneous catalysts; the percentage deuterium incorporation is a function of the kind of solvent used.

Development of a microwave-enhanced isotopic labelling procedure based on the Eschweiler–Clarke methylation reaction

A number of primary and secondary amines have been rapidly methylated under microwave-enhanced conditions using formic acid-formaldehyde mixtures, providing a route to 2H(D)-containing compounds and the potential for 3H(T), 11C, 13C and 14C labelling.

Development of combined microwave-enhanced labelling procedures for maximising deuterium incorporation

Abstract Combined hydrogenation/aromatic dehalogenation under microwave-enhanced conditions provides a rapid route to deuterium labelled compounds with enhanced isotopic incorporation.

Molecular modelling of interactions at the composite interfaces between electrolytically surface-treated carbon fibre and epoxy resin

Two carbon fibre models, based on microscopic and XPS evidence of electrochemical surface treatment, have been proposed. A diagonal graphitic plane, comprising 52 six-membered rings (in a 4×13 configuration) and of 150 carbon atoms, was built as the principal, non-surface-treated carbon fibre model. Three layers of graphitic planes, each comprising 117 six-membered rings (in a 9×13 configuration) and of 300 carbon atoms, formed the multi-layer graphitic model. The nature and level of surface treatment was represented by the introduction of hydroxy (OH) and carboxy (COOH) groups: each time, a C–C bond was broken along the edge of the plane, and a pair of OH and COOH groups was added to the graphitic plane. Six pairs of OH and COOH were introduced gradually. The functional groups were distributed evenly along the edge of each graphitic plane. Their non-covalent bonding interaction with various amine-cured epoxy polymer models was simulated using the Cerius 2 BLENDS method. Δ mix G was used to indicate the interaction, and hence the interfacial adhesion. The results show a trend, in relation to the level of surface treatment, in agreement with experimental data of composite interlaminar shear strength (ILSS).

Microwave enhanced decarboxylations of aromatic carboxylic acids: improved deuteriation/tritiation potential †

Decarboxylation of aromatic carboxylic acids under microwave enhanced conditions is an increasingly attractive method of preparing deuterium/tritium labelled compounds.

Microwave-enhanced hydrogen isotope exchange studies of heterocyclic compounds

The microwave-enhanced hydrogen–deuterium exchange reaction of a number of nitrogen-containing heterocyclic compounds has been achieved extremely rapidly (<20 min) via their hydrochloride salts, whilst the corresponding Raney-nickel catalysed reactions of indole and N-methylindole are also complete in a similar time interval. Furthermore, the pattern of labelling in the latter reaction depends critically on the choice of solvent used.

Molecular modelling of interactions at the composite interface between surface-treated carbon fibre and polymer matrices: the influence of surface functional groups

To simulate the results of surface treatments, commonly encountered functional groups were introduced onto the surface of the carbon fibre model. The carbon fibre model used in this study is based on the single layer diagonal graphitic plane, comprising 52 six-membered rings, in a 4×13 configuration, and of 150 carbon atoms. Surface treatment was represented by the introduction of functional groups (–R): each time, a C–C bond was broken along the edge of the plane, and a pair of –R groups was added to the graphitic plane. The total number of functional groups (n) was six. The effect of these functional groups on the non-covalent bonding interactions at the composite interface between carbon fibre and epoxy resin was investigated using a previously established BLENDS method. The compatibility of the resin and fibre in this model, indicated by the interaction parameter χ(T ), was dependent upon two factors: steric bulk and electrostatic interactions. The halogen substituents show a decrease in χ(T ), as one descends the group. Maximum interaction tends to be a function of steric bulk and polarizability in this group. The alkyl (CnH2n+1) and phenyl substituents also show a decreasing trend inχ(T ) with increasing size, although the interaction parameter with methyl is anomalously low in all cases.

Microwave Enhanced Deuteriations in the Solid State using Alumina Doped Sodium Borodeuteride

A number of deuteriated alcohols are rapidly (ca. 1 min) synthesised through the microwave enhanced solid state reduction of the corresponding aldehydes and ketones using alumina doped sodium borodeuteride (NaBD4).