Synthesis of trimethoxysilyl-terminated poly(12-hydroxy-stearic acid) and the subsequent grafting onto charged silica particles

A versatile method for grafting polymers on nanoparticles

We report a simple and versatile method for grafting polymers on nanoparticles. A procedure was developed for the synthesis and subsequent functionalization of silica nanoparticles with a perfluorophenylazide. Polymers were then grafted by the photochemically induced insertion reactions of the perfluorophenylnitrene. Polystyrene, poly(4-vinylpyridine), and poly(2-ethyl-2-oxazoline) were successfully grafted on silica nanoparticles. Grafting density was studied with regard to polymer concentration and molecular weight.

Polymer-in-a-silica-crust membranes: macroporous materials with tunable surface functionality

We report on alkaline hydrolysis of tetraethoxysilane (Stöber synthesis) inside a macroporous polymer matrix resulting in a homogeneous coverage of silica onto the polymer surface. The encapsulation of the polymer struts by a continuous silica crust allows further functionalization with hydrophilic and hydrophobic silylating agents. The porous silica polymeric hybrid material combines the morphological control and mechanical flexibility of the polymeric matrix with the convenient surface modifications developed for glass and amorphous silica. This concept is applied to macroporous membranes where alteration in surface functionality allows tuning of hydrophobicity (contact angle and liquid entry pressure), streaming potential, and adsorption capacity of double-stranded DNA.

Synthesis of SiO2/polystyrene nanocomposite particles via miniemulsion polymerization

The SiO(2)/polystyrene nanocomposite particles were synthesized through miniemulsion polymerization by using sodium lauryl sulfate surfactant (SLS), hexadecane costabilizer in the presence of silica particles coated with methacryloxy(propyl)trimethoxysilane. Core-shell or other interesting morphology composite particles were obtained depending on the size of the silica particles and the surfactant concentration employed. By adjusting these parameters, it was possible to control the size and morphology of the composite particles.

Grafting of PEO to glass, nitinol, and pyrolytic carbon surfaces by gamma irradiation

Glass, nitinol, and pyrolytic carbon surfaces were grafted with poly (ethylene oxide) (PEO) and PEO-containing Pluronic surfactants by gamma irradiation. These substrates were coated with a primer layer of trichlorovinylsilane (TCVS), which allows grafting of organic polymers. The TCVS-coated substrates were adsorbed with PEO or Pluronics and exposed to 0.3 Mrad of gamma radiation to graft the polymer to the surface. PEO-grafted substrates were characterized by contact angle measurement, X-ray photoelectron spectroscopy, fibrinogen adsorption, and platelet adhesion and activation. Surface modification with PEO reduced fibrinogen adsorption by as much as 99%. Platelet adhesion was significnatly reduced or prevented on the modified surfaces. Protein- and platelet-resistance effects were independent of hydrophilicity of the PEO-grafted surfaces. Polymer grafting by gamma radiation to TCVS-coated substrates provides a facile process to improve thromboresistance of inorganic biomaterials.