Surface Functionalization of Poly(tetrafluoroethylene) Films via Consecutive Graft Copolymerization with Glycidyl Methacrylate and Aniline

Nanostructured bio-functional polymer brushes

Structured poly(glycidyl methracrylate) (poly-GMA) brushes have been grafted onto flexible fluoro-polymer films using a radiation grafting process. The reactive epoxide of poly-GMA provides the basis for a versatile biofunctionalization of the grafted brushes. Structure definition by extreme ultraviolet (EUV) exposure allowed nanometer-scale resolution of periodic patterns. By variation of the exposure dose the height of the grafted structures can be adapted in a wide range. Derivatization of the grafted brushes included reaction with various amines with different side chains, hydrolysis of the epoxide to diols to increase protein resistance and introduction of ionic groups to yield poly-electrolytes. As an example for biofunctionalization, biotin was linked to the grafted brush and biofunctionality was demonstrated in a competitive biotin-streptavidin assay. In this article we also present a brief review of other approaches to obtain structured biofunctional polymer brushes.

Immobilization of DNA on microporous PVDF membranes by plasma polymerization

Microporous poly(vinylidene fluoride) (PVDF) membranes with different porous surface morphologies were prepared by immersion-precipitation from coagulation baths of different strengths. On these membranes single-strand deoxyribonucleic acid (ss-DNA) was covalently immobilized by a dual-step procedure. First, poly(glycidyl methacrylate) (PGMA) was grafted on PVDF membranes by plasma-induced free radical polymerization. Then, ss-DNA was bonded to PGMA through ring-opening reactions of epoxies with amine to form amino alcohols. The highest attainable graft yield of PGMA on PVDF membrane was 0.3 mg/cm(2), which was the case when a highly porous PVDF membrane was employed as the substrate. For immobilization of ss-DNA, the yield was found to depend significantly on the reaction temperature and pH. The maximal value was 48.5 mug/cm(2). Furthermore, adsorption tests of anti-DNA antibody were carried out on membranes with and without immobilized ss-DNA using serum obtained from systemic lupus erythematosus patients. The results indicated that the immobilized DNA could effectively adsorb the antibody in the serum.

Fabrication of Shape-Controllable Polyaniline Micro/Nanostructures on Organic Polymer Surfaces: Obtaining Spherical Particles, Wires, and Ribbons

A novel strategy was developed in order to prepare various micro/nanostructured polyanilines (PANI) on polymer substrates. The strategy involved two main steps, i.e., a grafting polymerization of acrylate acid (AA) onto the surface of a polypropylene (PP) film and subsequently an oxidative polymerization of aniline on the grafted surface. By tuning the conformation of the surface-grafted poly acrylate acid (PAA) brushes, as well as the ratio of AA to aniline, the shape of the PANIs fixated onto the surfaces of the polymer substrate could be controlled to go from spherical particles to nanowires and eventually to nanoribbons. In these structures, the PAA brushes not only acted as templates but also as dopants of PANI, and thereby, the nanostructured PANIs could be strongly bonded with the substrate. In addition, the surface of the PP films grafted with polyaniline nanowires and nanoribbons displayed superhydrophobicity with contact angles for water of approxiamtely 145 and 151 degrees , respectively.

Confirmation of heavy metal ions in used lubricating oil from a passenger car using chelating self-assembled monolayer

In order to prevent engine failure, the oil must be changed before it loses its protective properties. It is necessary to monitor the actual physical and chemical condition of the oil to reliably determine the optimum oil-change interval. Our study focuses on the condition of the lubricating oil in an operated car engine. Shear stress curves and viscosity curves as a function of the shear rate for fresh and used lubricating oil were examined. Metal nitrate was detected in the lubricating oil from the operated car engine through the use of a chelating self-assembled monolayer.