Search results for " modifica"
showing 10 items of 817 documents
Transition to Reinforced State by Percolating Domains of Intercalated Brush-Modified Cellulose Nanocrystals and Poly(butadiene) in Cross-Linked Compo…
2013
The classic nanocomposite approach aims at percolation of low fraction of exfoliated individual reinforcing nanoscale elements within a polymeric matrix. By contrast, many of the mechanically excellent biological nanocomposites involve self-assembled and space-filled structures of hard reinforcing and soft toughening domains, with high weight fraction of reinforcements. Here we inspect a new concept toward mimicking such structures by studying whether percolation of intercalated domains consisting of alternating rigid and reinforcing, and soft rubbery domains could allow a transition to a reinforced state. Toward that, we present the functionalization of rigid native cellulose nanocrystals …
ePTFE functionalization for medical applications
2021
Abstract Polytetrafluoroethylene (PTFE) is a ubiquitous material used in implants and medical devices in general due to its high biocompatibility and inertness; blood vessels, heart, jawbone, nose, eyes, or abdominal wall can benefit from its properties in the case of disease or injury. Its expanded version, ePTFE, is an improved version of PTFE with better mechanical properties, which extend its medical applications. However, ePTFE implants often lack improvement in properties such as antibacterial, antistenosis, or tissue integration properties. Improvements in these properties by several strategies of functionalization for medical purposes are discussed in this review. Covalent and non-c…
Nonthrombogenic, Biodegradable Elastomeric Polyurethanes with Variable Sulfobetaine Content
2014
For applications where degradable polymers are likely to have extended blood contact, it is often important for these materials to exhibit high levels of thromboresistance. This can be achieved with surface modification approaches, but such modifications may be transient with degradation. Alternatively, polymer design can be altered such that the bulk polymer is thromboresistant and this is maintained with degradation. Toward this end a series of biodegradable, elastic polyurethanes (PESBUUs) containing different zwitterionic sulfobetaine (SB) content were synthesized from a polycaprolactone-diol (PCL-diol):SB-diol mixture (100:0, 75:25, 50:50, 25:75 and 0:100) reacted with diisocyanatobuta…
Fast Polymeric Functionalization Approach for the Covalent Coating of MoS2 Layers
2021
We present the covalent coating of chemically exfoliated molybdenum disulfide (MoS2) based on the polymerization of functional acryl molecules. The method relies on the efficient diazonium anchoring reaction to provoke the in situ radical polymerization and covalent adhesion of functional coatings. In particular, we successfully implement hydrophobicity on the exfoliated MoS2 in a direct, fast, and quantitative synthetic approach. The covalent functionalization is proved by multiple techniques including X-ray photoelectron spectroscopy and TGA-MS. This approach represents a simple and general protocol to reach dense and homogeneous functional coatings on 2D materials.
Synthesis of Au-CdS@CdSe Hybrid Nanoparticles with a Highly Reactive Gold Domain.
2017
We propose a novel route to synthesize semiconductor–gold hybrid nanoparticles directly in water, resulting in much larger gold domains than previous protocols (up to 50 nm) with very reactive surfaces which allow further functionalization. This method advances the possibility of self-assembly into complex structures with catalytic activity toward the reduction of nitro compounds by hydrides. The large size of these gold domains in hybrid particles supports efficient light scattering at the plasmon resonance frequency, making such structures attractive for single-particle studies.
Anti-bacterial activity of graphene oxide as a new weapon nanomaterial to combat multidrug-resistance bacteria.
2016
Antibiotic resistance in microbial pathogens has become a serious health problem in the world. The increasing spread of hospital acquired infections especially in immunocompromised and cancer patients caused by multidrug-resistant (MDR) microbial pathogens is restricting the choices for impressive antibiotic therapy. So many efforts have been made to develop new compounds with antimicrobial activity. In recent years, nanoparticles, particularly graphene oxide (GO) nanoparticles have found many applications in various fields, including antibacterial action, pathogens bio detection, cancer therapy, and drug and gene delivery. The use of graphene oxide as an antibacterial agent for the treatme…
Design of siliceous lignins – Novel organic/inorganic hybrid sorbent materials
2009
Novel nanoporous lignin(lignocellulose)/SiO2 hybrid materials were designed using the sol–gel process. X-ray photoelectronic spectroscopy, Fourier transform infrared spectroscopy and 29Si and 13C nuclear magnetic resonance spectroscopy were applied to characterize the hybrids’ surface and bulk structure. Nitrogen and water vapor sorption were used for assessment of porous structure parameters and hydrophobization of matrices, respectively. The efficiency of the hybrid materials obtained was proved by adsorption tests with potential inorganic (Cu2+) and organic (2,4-dichlorophenoxyacetic acid) pollutants.
Reversible guest-induced gate-opening with multiplex spin crossover responses in two-dimensional Hofmann clathrates.
2021
Spin crossover (SCO) compounds are very attractive types of switchable materials due to their potential applications in memory devices, actuators or chemical sensors. Rational chemical tailoring of these switchable compounds is key for achieving new functionalities in synergy with the spin state change. However, the lack of precise structural information required to understand the chemical principles that control the SCO response with external stimuli may eventually hinder further development of spin switching-based applications. In this work, the functionalization with an amine group in the two-dimensional (2D) SCO compound {Fe(5-NH2Pym)2[MII(CN)4]} (1M, 5-NH2Pym = 5-aminopyrimidine, MII =…
Influence of alkylphosphonic acid grafting on the electronic and magnetic properties of La2/3Sr1/3MnO3 surfaces
2015
Self-assembled monolayers (SAMs) are highly promising materials for molecular engineering of electronic and spintronics devices thanks to their surface functionalization properties. In this direction, alkylphosphonic acids have been used to functionalize the most common ferromagnetic electrode in organic spintronics: La2/3Sr1/3MnO3 (LSMO). However, a study on the influence of SAMs grafting on LSMO electronic and magnetic properties is still missing. In this letter, we probe the influence of alkylphosphonic acids-based SAMs on the electronic and magnetic properties of the LSMO surface using different spectroscopies. We observe by X-ray photoemission and X-ray absorption that the grafting of …
How Electrical Heterogeneity Parameters of Ion-Exchange Membrane Surface Affect the Mass Transfer and Water Splitting Rate in Electrodialysis
2020
Electrodialysis (ED) has been demonstrated as an effective membrane method for desalination, concentration, and separation. Electroconvection (EC) is a phenomenon which can essentially increase the mass transfer rate and reduce the undesirable water splitting effect. Efforts by a number of researchers are ongoing to create conditions for developing EC, in particular, through the formation of electrical heterogeneity on the membrane surface. We attempt, for the first time, to optimize the parameters of surface electrical heterogeneity for ion-exchange membranes used in a laboratory ED cell. Thirteen different patterns on the surface of two Neosepta anion-exchange membranes, AMX and AMX-Sb, w…