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Surface modification
About: Surface modification is a research topic. Over the lifetime, 35544 publications have been published within this topic receiving 859567 citations.
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TL;DR: Sorption data are consistent with the idea that incorporated surface oxides create polar regions that reduce the surface area available for naphthalene sorption, and highlight the important role of surface chemistry in controlling the environmental properties of CNTs.
Abstract: As greater quantities of carbon nanotubes (CNTs) enter the environment, they will have an increasingly important effect on the availability and transport of aqueous contaminants. As a consequence of purification, deliberate surface functionalization, and/or exposure to oxidizing agents after release to the environment, CNTs often contain surface oxides (i.e., oxygen containing functional groups). To probe the influence that surface oxides exert on CNT sorption properties, multiwalled CNTs (MWCNTs) with varying oxygen concentrations were studied with respect to their sorption properties toward naphthalene. For pristine (as-received) MWCNTs, the sorption capacity was intermediate between that of a natural char and a granular activated carbon. Sorption data also reveal that a linear relationship exists between the oxygen content of MWCNTs and their maximum adsorption capacity for naphthalene, with 10% surface oxygen concentration resulting in a roughly 70% decrease in maximum adsorption capacity. The relative distribution of sorption energies, as characterized by Freundlich isotherm exponents was, however, unaffected by oxidation. Thus, the data are consistent with the idea that incorporated surface oxides create polar regions that reduce the surface area available for naphthalene sorption. These results highlight the important role of surface chemistry in controlling the environmental properties of CNTs.
288 citations
TL;DR: Tuning the surface chemistry and design of magnetic nanoparticles are described in relation to their applicability in advanced medical technologies and biotechnologies including magnetic resonance imaging (MRI) contrast agents, targeted drug delivery, magnetic separations and immobilizations of proteins, enzymes, antibodies, targeting agents and other biosubstances.
288 citations
TL;DR: In this article, the surface properties of nanocrystalline zeolites and hollow zeolite structures were tailored through functionalization of surface silanol groups, which can be used as building blocks to construct larger, hollow structures with encapsulated metal or organic species.
Abstract: Nanocrystalline zeolites are porous nanomaterials with crystal sizes of less than 100 nm that possess unique external and internal surface reactivity. Nanocrystalline zeolites, such as silicalite, ZSM-5 and Y, were synthesized and extensively characterized by powder X-ray diffraction, nitrogen adsorption isotherms, dynamic light scattering, and electron microscopy. Spectroscopic characterization of the nanocrystalline zeolites by FTIR and solid-state NMR provided detailed structural information about internal and external surface sites. The nanocrystalline zeolites were also used as building blocks to form larger, hollow zeolite structures with encapsulated metal or organic species. The surface properties of nanocrystalline zeolites and hollow zeolite structures were tailored through functionalization of surface silanol groups. Applications of nanocrystalline zeolites and zeolite structures in the selective catalytic reduction of NOx and the photoreduction of Cr(VI) to Cr(III) in aqueous solution were inv...
288 citations
TL;DR: Findings indicate that poly(alpha-hydroxy ester) materials can be readily mineralized using a biomimetic process, and that the impetus for mineral nucleation in this system appears more complicated than the simple electrostatic interactions proposed in previous biomineralization theory.
Abstract: Mineralization in biological systems is a widespread, yet incompletely understood phenomenon involving complex interactions at the biomacromolecule−mineral nucleus interface. This study was aimed at understanding and controlling mineral formation in a poly(α-hydroxy ester) model system, to gain insight into biological mineralization processes and to develop biomaterials for orthopaedic tissue regeneration. We specifically hypothesized that providing a high surface density of anionic functional groups would enhance nucleation and growth of bonelike mineral following exposure to simulated body fluids (SBF). Polymer surface functionalization was achieved via hydrolysis of 85:15 poly(lactide-co-glycolide) (PLG) films. This treatment led to an increase in surface carboxylic acid and hydroxyl groups, resulting in a substantial increase in polymer surface energy from 42 to 49 dynes/cm2. Treated polymers exhibited a 3-fold increase in heterogeneous mineral grown and growth of a continuous mineral film on the poly...
286 citations
TL;DR: The micellar shells of these particles were functionalized using covalent chemistry that would not ordinarily be possible on the magnetic particle surface, providing a new route to technological applications of hydrophobic magnetic nanomaterials that lack appropriate conjugate surface chemistry.
Abstract: We report the synthesis, characterization, and covalent surface chemistry of “magnetomicelles”, cross-linked, amphiphilic block-copolymer micelles that encapsulate superparamagnetic iron oxide nanoparticles. Because these composite nanostructures assemble spontaneously from solution by simultaneous desolvation of nanoparticle and amphiphilic poly(styrene250-block-acrylic acid13) components, explicit surface functionalization of the particles is not required, and the encapsulation method was applied to different magnetic nanoparticle sizes and compositions. TEM images of the magnetomicelles illustrated that the number of encapsulated particles could be dictated rationally by synthetic conditions. The magnetic properties of the particles were characterized by SQUID magnetometry and followed the general Langevin magnetic model for superparamagnetic materials. The micellar shells of these particles were functionalized using covalent chemistry that would not ordinarily be possible on the magnetic particle surf...
285 citations