Quinine doped hybrid sol-gel coatings for wave guiding and optical applications

Pure and quinine doped silica coatings have been prepared over sodalime glasses. The coatings were consolidated at low temperature (range 60-180 A degrees C) preserving optical activity of quinine molecule. We designed a device to test the guiding properties of the coatings. We confirmed with this device that light injected in pure silica coatings is guided over distances of meters while quinine presence induces isotropic photoluminescence. With the combined use of both type of coatings, it is possible to design light guiding devices and illuminate regions in glass elements without electronic circuits

Photochromic materials by postpolymerisation surface modification

Photochromic materials are available by a postpolymerization surface modification of diverse polymers in a multistep sequential process mediated, first, by carbene insertion chemistry, second, by diazonium coupling with a tethered precursor, and finally by coupling to a spiropyran. This three-step sequence is efficient, and surface loading densities of 1013 molecules cm-2 are typically achievable, leading to materials with observable photochromic and wettability behavior, which operate over multiple cycles without significant photobleaching or loss of efficacy. Materials suitable for application in this process include both reactive, but also lower surface energy polymers. Although the process is particularly efficient for high surface area materials, surface modification onto lower surface area substrates, while being intrinsically less efficient, is nonetheless sufficiently effective that changes in macroscopic photochromic properties are readily observable

Antibacterial drug releasing materials by post-polymerization surface modification

Functional materials are available by the post-polymerization surface modi¯cation of diverse polymers in a three-step process mediated, ¯rstly, by carbene insertion chemistry, secondly, by diazonium coupling, and thirdly by modi¯cation with a remotely tethered spiropyran unit, and these materials may be used for the reversible binding and release of Penicillin V. Surface loading densities of up to 0.19 mmol/g polymer are achievable, leading to materials with higher loading densities and release behavior relative to unmodi¯ed controls, and observable antibacterial biocidal activity

Antibacterial drug releasing materials by post-polymerization surface modification

Functional materials are available by the post-polymerization surface modi¯cation of diverse polymers in a three-step process mediated, ¯rstly, by carbene insertion chemistry, secondly, by diazonium coupling, and thirdly by modi¯cation with a remotely tethered spiropyran unit, and these materials may be used for the reversible binding and release of Penicillin V. Surface loading densities of up to 0.19 mmol/g polymer are achievable, leading to materials with higher loading densities and release behavior relative to unmodi¯ed controls, and observable antibacterial biocidal activity

Chemical functionalization of polyethylene surfaces by plasma-assisted carbene insertion

Controlled surface modification of PE is achieved by an efficient and facile approach via plasma-assisted carbene insertion generated using diazo chemistry. The combination of plasma and carbene insertion shows a synergistic effect, which leads to an obvious enhancement of surface grafting, as shown qualitatively by a combination of IR and UV reflectance spectroscopy, and XPS analysis. The chemical modification may be observed spectroscopically, and the approach provides an opportunity for the convenient modification of low surface energy materials

A study of diazonium couplings with aromatic nucleophiles both in solution and on a polymer surface

Diazonium coupling is a technique finding wider application to materials and biological science, for hybridization and linking processes, and for the construction of responsive surface functionality. For this reason, detailed examination of solution and surface processes was warranted, and results of such a study are reported here. The modification of polystyrene surfaces was examined as a model, and the process compared to a solution mimic using N,N-dimethylaniline. It was confirmed that solution and solid surface reactions proceed in a similar manner in terms of the chemical functionality generated, but with lower chemical efficiency and reaction times slower for the latter, in a reaction which was pH dependent. The solution process was shown to give only the trans-azo para- coupled products. Whilst there are clear similarities between the solution and surface chemistry, the efficiency of coupling at a surface is not necessarily replicated in the chemical yield of the mimicking solution processes, but nonetheless provides an alternative to other Click-type surface modifications. It should not be assumed that such couplings occur with quantitative efficiency at the surface

A study of diazonium couplings with aromatic nucleophiles both in solution and on a polymer surface

Diazonium coupling is a technique finding wider application to materials and biological science, for hybridization and linking processes, and for the construction of responsive surface functionality. For this reason, detailed examination of solution and surface processes was warranted, and results of such a study are reported here. The modification of polystyrene surfaces was examined as a model, and the process compared to a solution mimic using N,N-dimethylaniline. It was confirmed that solution and solid surface reactions proceed in a similar manner in terms of the chemical functionality generated, but with lower chemical efficiency and reaction times slower for the latter, in a reaction which was pH dependent. The solution process was shown to give only the trans-azo para- coupled products. Whilst there are clear similarities between the solution and surface chemistry, the efficiency of coupling at a surface is not necessarily replicated in the chemical yield of the mimicking solution processes, but nonetheless provides an alternative to other Click-type surface modifications. It should not be assumed that such couplings occur with quantitative efficiency at the surface

One-step chemical functionalization of polyethylene surfaces via diarylcarbene insertion

Three diarylcarbene derivatives with reactive groups were synthesized and used to graft functional groups onto a plasma-modified polyethylene surface via one-step carbene insertion. The modification is observable spectroscopically, and this one-step strategy provides facile and efficient tool to modify the surface macroscopic properties of low surface energy materials