Showing papers by "Igor Luzinov published in 2003"

Synthesis and Surface Morphology of High-Density Poly(ethylene glycol) Grafted Layers

Abstract: The present study was focused on permanent grafting of poly(ethylene glycol) (PEG) layers (brushes) from the melt to adsorbed reactive macromolecules. A poly(glycidyl methacrylate) (PGMA) was used to form the reactive primary adsorbed layer. It was found that a thin (1.5 nm) PGMA layer had a high grafting efficiency, and elevated temperatures considerably accelerated the grafting process. The grafting extent was eventually limited by concentration and accessibility of functional reactive groups in the primary adsorbed layer. Several distinct types of brush morphologies were observed depending on the grafted layer height. Isolated crystals were detected for brushes possessing lower grafting density. At higher levels of PEG attachment, the crystalline formations uniformly covered the entire surface of the substrate. The development of highly extended crystalline formations on the surface and marked expansion of the PEG brushes in water indicated that an extremely high grafting density was attained. The deve...

Polystyrene Layers Grafted to Macromolecular Anchoring Layer

Abstract: Dense and homogeneous grafted polymer layers were anchored from the melt onto a silicon wafer modified with a macromolecular anchoring layer rich in epoxy functional groups. A monolayer of poly(gly...

Bidisperse Mixed Brushes: Synthesis and Study of Segregation in Selective Solvent

Abstract: We prepare a series of mixed brushes of two incompatible polymers, polystyrene (PS) and poly(2-vinylpyridine) (P2VP) grafted by end groups to Si wafers from carboxyl-terminated P2VP (MW(P2VP) 42 kg/mol) and carboxyl-terminated PS. The molecular mass of PS ranged from 2.98 to 75 kg/mol. The mixed brushes are bidisperse (asymmetric) with respect to the difference of molecular mass of P2VP and PS while the polydispersity of PS and P2VP is narrow. We expose the mixed brushes to selective solvents (toluene for PS and ethanol for P2VP). The morphology and surface chemical composition are investigated using scanning probe microscopy and contact angle measurements. For small chain length asymmetry, the brushes exhibit lateral and perpendicular segregation, and the structure depends on the solvent quality. Upon increasing the molecular weight asymmetry, we encounter the transition from a morphology of laterally segregated domains to a layered (sandwich-like) structure. The location of this transition can be tuned ...

Surface Morphology of Mechanically Heterogeneous Ultrathin Polymer Films

Abstract: We studied the formation and morphology of mechanically heterogeneous ultrathin film consisting of a rubbery matrix and stiff domains deposited on silicon surface. Polystyrene (PS) was used for the...

Gradient polymer brushes

Abstract: Introduction Substrates with gradient surface properties are interesting objects for investigation from both theoretical and practical points of view. The gradient surfaces have been successfully utilized in combinatorial methods of data collection in multiparameter space, substantially decreasing time and labor requirements. They have shown great advantages in the investigation of biological interactions along their length in one single experiment, allowing minimizing biological variations. The gradient surfaces also offer a plenty of opportunities to design responsive materials. On the other hand ultrathin end-grafted polymer layers are well known to affect dramatically the surface properties of substrates such as adhesion, lubrication, wettability, friction, and biocompatibility and, definitely, can be used to generate the gradient of properties on a substrate surface. In the present work, we report the results of synthesis and characterization of gradient polymer brushes prepared from polymers covalently attached to the surface. The brushes were grafted to the surface through reactive poly(glycidyl methacrylate) (PGMA) layers.