Viktor Klep

Hydrophobic Modification of Polymer Surfaces via “Grafting to” Approach

Hydrophobic grafted polymer layers were permanently anchored from the melt onto poly(ethylene terephthalate) (PET) and nylon substrates modified with air plasma and poly(glycidyl methacrylate) (PGMA) anchoring layer. Polypentafluorostyrene (PPFS) of different molecular weights with an end carboxyl group was used for the grafting. Atomic force microscopy imaging revealed that, in general, the grafted chains evenly covered all substrates. Thickness of the grafted layer increased with temperature and time of grafting. To reach a significant level of grafting and consequently high hydrophobicity temperature above 140°C, 5 min of grafting had to be used. For longer grafting time (1 h) the hydrophobicity could be reached at 120°C. The thickness of the grafted layer should be at least 2–3 nm to attain the high water‐contact angle. The polymer grafting technique developed could be readily applied to surface modification of fibers and textiles leading to generation of hydrophobic fibrous materials. In Commemoration of the Contributions of Professor Valery P. Privalko to Polymer Science.

Extraction of metals from aqueous systems employing capillary-channeled polymer (C-CP) fibers modified with poly(acrylic acid) (PAA)

Polyethylene terephthalate (PET, polyester) capillary-channeled polymer (C-CP) fibers were employed as the base structure for surface modification to provide a sorbent for solid phase extraction (SPE) of aqueous cations. Surface functionalization with polyacrylic acid (PAA) was achieved using a “grafting to” approach, yielding a stable sorbent that has the potential of being employed over a large range of pH values and a variety of sample matrices. PAA was chosen for surface modification because the repeating acrylic acid monomeric unit, which contains a carboxylic acid, has the ability to bind metal ions. In a micropipette-tip SPE format, these PAA-functionalized C-CP fibers showed the ability to efficiently bind several metals (Cu2+, Cu+, Ni2+, Fe3+, UO22+), while elution could be achieved with extremely low concentrations of hydrochloric acid (1 ml of 0.005%), resulting in overall recoveries of greater than 88%. A single tip was carried throughout the entire study as a control, and showed overall recoveries averaging 96% over the course of 19 extraction experiments and a 12-month period, demonstrating the chemical stability of the sorbent material, and suggesting the potential of the C-CP fiber SPE tips to be used multiple times.

Nanocomposite liquids for 193 nm immersion lithography: a progress report

Immersion lithography is a new promising approach capable of further increasing the resolution of semiconductor devices. This technology requires the development of new immersion media that satisfy the following conditions: the media should have high refractive index, be transparent and photochemically stable in DUV spectral range. They should also be inert towards photoresists and optics and be liquid to permit rapid scanning. Here we propose and explore a novel strategy in which high refractive index medium is made of small solid particles suspended in liquid phases (nanocomposite liquids). The dielectric particles have high refractive index and the refractive index of nanocomposite liquids becomes volume weighted average between refractive indices of nanoparticles and the liquid phase. We investigate aluminum oxide (alumina) nanoparticles suspended in water. Alumina is known to have high (1.95) refractive index and low absorption coefficient at 193 nm. Alumina nanoparticles were prepared by chemical methods followed by removal of organic molecules left after hydrolysis reactions. Measurements of optical and reological properties of the nanocomposite liquid demonstrated potential advantage of this approach for 193 nm immersion lithography.

Synthesis of poly(styrene-block-ethylene oxide) copolymers by anionic polymerization and acid cleavage into its constituent homopolymers for the formation of ordered nanoporous thin films

Abstract Well-defined cleavable poly(styrene-block-ethylene oxide) polymers were prepared by living anioinc polymerization, using cumyl potassium as the initiator. These polymers contained an acid cleavable moiety, such as diphenyl methyl or anthracenyl methyl ether linkage, between polystyrene and poly ethylene oxide block. Atomic force microscopy (AFM) studies on the thin films illustrate the formation of nanoporous architecture due to acid cleavage of the polyethylene oxide fraction.