Light-sensitive materials as azo-polymers have interesting applications in microelectronics, biology, or energy storage, due to their capacity to change their supramolecular ordering. Light-induced modifications result in i) changes in the azobenzene-groups dipole moment due to the trans-cis isomerization, ii) thermal backward cis-trans relaxation, and iii) re-ordering of the polymer chain conformation. Conjugation of these phenomena leads to mass transport in the solid state, which is still not well understood. Changes in the surface properties of non-substituted and p-CF3,-CN,-NO2-substituted azophenoxy-polysiloxane films, before and after photo-excitation, were examined. Molecular simulations were performed to evaluate the dipole-moments of the trans and cis p-substituted azobenzene groups and provide a general vision of the spatial arrangement of polymer chains. The role of trans-cis back relaxation and that of the polymer matrix relaxation on the surface and bulk of the materials was discussed. Surface free energy determination of the non-substituted azophenoxy-polysiloxane suggested that the relaxation process is dominated by the thermal slow back-isomerization of the cis fraction and not by the motion of a glassy polymer matrix involving both the surface and bulk. A less clear situation was presented by the semi-crystalline polysiloxanes with electron-withdrawing groups substituted in the para-position. This was attributed mainly to the similar values of the dipole-moment of trans and cis azo-group, the former being slightly more dipolar than the latter.

The stoichiometric noncovalent imprinting of pinacolyl methylphosphonate (PMP), a degradation product of a chemical warfare agent, has been investigated. A rational approach consisting of controlling the number of specific sites produced during the polymerization was carried out in order to design the methacrylic acid (MAA)-based imprinted polymers. The objective of the method was to study by NMR spectroscopy the molecular association process between the monomer (MAA) and the template (PMP) in solution. Accurate variations in the chemical shifts of H-1 and C-13 were determined in a series of samples at various concentrations in the mixture of acetonitrile/toluene (3:1, v/v). By using an elaborated data treatment, we were able to simultaneously determine the stoichiometry, the association constant, and the condensation degree of the resulting complex. On the basis of these results, a stoichiometric noncovalent PMP-imprinted polymer was subsequently synthesized. Adsorption isotherms of the materials were measured and confronted with those of an imprinted polymer conventionally synthesized with excess monomer. These results established for the first time, the feasibility of imprinted polymers with low-molecular-weight and poorly functionalized templates such as pinacolyl methylphosphonate via stoichiometric noncovalent interactions. Batch binding tests were also carried out on a series of three analogue phosphonates in order to elucidate the influence of the functionality, shape, and size of the analyte on the adsorption properties of the polymers.

The multiplication of terrorist actions in the recent events is alarming and the detection of chemical warfare agents (CWAs) has become one of the highest research priorities in the fields of security and public health. The biomimetic properties of molecularly imprinted polymers (MIPs) render them attractive for molecular recognition as well as sensing purposes. The degradation products of easily hydrolysable organophosphorus nerve agents such as pinacolyl methylphosphonate (PMP), a hydrolysis by-product of soman, are often used as templates in MIP synthesis. In this study, we describe the first example of PMP-imprinted polymer microspheres synthesized by precipitation polymerization. This one-step process involves methacrylic acid (MAA) as the monomer and divinylbenzene (DVB) as the cross-linker, in a toluene/acetonitrile mixture. Subsequent morphological characterizations of the PMP-imprinted particles show that they have diameters between 1 and 10 mum (as opposed to 4-5 mum for the non-imprinted microspheres), surface areas of up to 680 m(2) g(-1) and high porosities with pore sizes smaller than 2 nm. The present investigation also evidences the imprinting effect via batch binding experiments and reports on the use of a novel fluorescence-based methodology, where 4-methylumbelliferone (4MU) is utilised as a sensing agent to determine the PMP concentration in solution.

Alzheimer's disease is characterized by the presence of beta-amyloid fibril formation. The inhibition of this peptide accumulation may be a prevention method for Alzheimer's disease. Several classes of molecules have been reported to inhibit beta-amyloid fibril formation and among them carbazoles. However, very few studies have been performed to determine the destination of such molecules in vivo and especially if they can pass the blood brain barrier. The aim of this paper is to study whether carbazoles could pass the blood brain barrier, i.e. if they can circumvent ATP Binding Cassette (ABC) transporters such as P-glycoprotein (P-gp) and Multidrug Resistance-associated protein (MRP1) which efficiently limit drug brain uptake. For this purpose we have synthesized a fluorescent derivative of carbazole benzothiazolium iodide 1,2 disubstituted ethylene (referred as carbazole thiazole: CT), which can be easily detected and followed in the pre-trial study phases in cells or in tissue. We use cellular models overexpressing P-gp and MRP1. Our results show that: i) CT is able to cross membranes and to penetrate rapidly inside the cells, ii) CT is a P-gp substrate and consequently its accumulation in P-gp overexpressing cells is very low, iii) CT is a poor MRP1 substrate. In addition once inside the cells, CT rapidly binds to DNA and is then slowly reduced by intracellular reducing agents. In conclusion, the efficiency of carbazole derivatives in inhibiting the beta-amyloid formation in vivo could be highly compromised because, as P-gp substrates, they will probably not cross the blood brain barrier.

Nondoped white organic light-emitting diodes using an ultrathin yellow-emitting layer of rubrene (5,6,11,12-tetraphenylnaphtacene) inserted on either side of the interface between a hole-transporting 4,4′-bis[N-(1-naphtyl)-N-phenylamino]biphenyl (α-NPB) layer and a blue-emitting 4,4′-bis(2,2′-diphenylvinyl)-1,1′-biphenyl (DPVBi) layer are described. Both the thickness and the position of the rubrene layer allow fine chromaticity tuning from deep blue to pure yellow via bright white with CIE coordinates (x=0.33, y=0.32), an ηext of 1.9%, and a color rendering index of 70. Such a structure also provides an accurate sensing tool to measure the exciton diffusion length in both DPVBi and NPB (8.7 and 4.9nm, respectively).

Summary Quaternary ammonium salts (QAS) were covalently-bound to epoxy resins of different DP in two steps: addition of a N,N-dialkylaminoethanethiol followed by the quaternization of the tertiary amine by an alkylbromide (C 8 H 17 Br to C 14 H 29 Br). The products were characterized by 1 H NMR spectroscopy. The QAS-containing oligomers were used as polyols to prepare polyurethane (PU) films by reaction with a triisocyanate. The films show a good bactericidal activity against Escherichia coli , which is preserved after 6 months of immersion in water.

Phenylene-carbazolylene copolymers with variable composition and properties were prepared by electrocatalyzed dehalogenative polycondensation of 4,4'-dihalobiphenyl and N-alkyl-3,6-dibromocarbazole mixtures in the presence of a zero valent nickel catalyst. The polymers are partly soluble in polar solvents and this solubility depends on the proportion of carbazolylene units in the materials. For a given composition, solubility increases with length of the aliphatic substituent linked to the nitrogen. The conductivity upon doping varies between those of the corresponding homopolymers and is a function of the length of the alkyl substituents. Thin films of these materials can be prepared either by solvent casting or by direct electrodeposition onto various supports. The electrochemical behavior is strongly dependent on the copolymer composition and reveals the existence of two distinct electronic states (two quantum wells): the first one is related to the presence of the carbazolylene units, while the second shows the presence of phenylene moieties.

Cathodic reduction of mixtures of 4,4′-dibromobiphenyl and 3,6-dibromo-N-ethylcarbazole, in the presence of zero-valent nickel complexes, leads to [phenylene-carbazolylene] random copolymers. According to the coupling mechanism and to physical features, the copolymer chains are expected to have a linear well-defined structure. Copolymers with a continuous molar ratio of comonomer units can be synthesized and the resulting properties lie between those of polyparaphenylene and the poly[N-ethyl-3,6-carbazolediyl] ones. In particular, partial solubility in organic media was obtained for copolymers rich in carbozolylene units, whereas higher conductivity was observed with materials rich in phenylene units (σ = 1 μ−1 cm−1).

La synthese de poly (3,3’N-ethylcarbazole) a ete realisee par reduction electrochimique du systeme NiBr2 , bipyridine/3,6 dibrono N-ethylcarbazole dans la N,N dimethyl acetamide. L’etude electroanalytique du systeme pendant la phase homogene de la polymerisation a permis de proposer un mecanisme de croissance des chaines.Le polymere obtenu est soluble dans divers solvants organiques et son dopage chimique conduit a un materiau electroactif dont la conductivite est situee dans le domaine 10–4 Ω–1 cm–1 .

The simultaneous interpenetration of two networks, one based on diglycidyl ether of bisphenol A crosslinked by an aliphatic diamine and the other one based on diglycidyl ether of bisphenol A dimethacrylate, leads to systems transparent to visible light. The measurement of glass transition temperature of these IPNs as a function of the composition and of the crosslinks density, gives relatively low and single values. This behavior is interpreted by the homogeneous structure of these systems.