Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 6 de 6
Filter
Add more filters










Database
Language
Publication year range
1.
ACS Appl Mater Interfaces ; 13(5): 6767-6777, 2021 Feb 10.
Article in English | MEDLINE | ID: mdl-33523621

ABSTRACT

The vast majority of light-emitting diode and liquid-crystal displays, solar panels, and windows in residential and industrial buildings use glass panels owing to their high mechanical stability, chemical resistance, and optical properties. Glass surfaces reflect about 4-5% of incident light if no antireflective coating is applied. In addition to energy losses in displays, surface reflections diminish picture quality. Engineering of antireflective coatings can be beneficial for all types of glass screens, specifically for large screens and touch-screen devices when scratch-resistance and self-cleaning properties of the glass surface are also desired. A scalable and robust approach to produce antireflective coatings for glass surfaces with desired optical and mechanical properties is introduced in this work. The developed coating mimics the structure of a moth-eye cornea. The coating is a subwavelength-microstructured thin layer on the glass surface made of a monolayer of hemispherical silica nanoparticles obtained by hydrothermal fusion of spherical particles to the glass substrate. The sequence of the particle deposition in the layer-by-layer process is adjusted to balance attractive-repulsive interactions among nanoparticles and between the nanoparticles and the glass surface to generate coatings with a high surface coverage of up to 70%, which exceeds the 54.7% limit of the random sequential addition model. This level of surface coverage allows for a combination of properties beneficial for the described applications: (i) an average reflectance of 0.5 ± 0.2% for a visible and near-infrared optical spectrum, (ii) an improved mechanical stability and scratch resistance, and (iii) non-wetting behavior.

2.
ACS Appl Mater Interfaces ; 11(20): 18268-18275, 2019 May 22.
Article in English | MEDLINE | ID: mdl-31033277

ABSTRACT

A facile route to biofouling-resistant porous thin-film membranes that can be fine-tuned for specific needs in diverse bioseparation, mass flow control, sensors, and drug delivery applications is reported. The proposed approach is based on combining two distinct macromolecular systems-a cross-linked poly(2-vinyl pyridine) network and a 3D-grafted polyethylene oxide (PEO) layer-in one robust porous material whose porosity can be adjusted within a wide range, covering the macroporous and mesoporous size regimes. Notably, this reconfigurable material maintains its antifouling properties throughout the entire range of pore size configurations because of a dense surface carpet of PEO chains with self-healing properties that are immobilized both onto the surface and inside the polymer network through what was termed 3D grafting. Experimental results are supplemented by computer simulations of a coarse-grained model of a porous membrane that shows qualitatively similar pore swelling behavior.


Subject(s)
Biofouling/prevention & control , Computer Simulation , Drug Delivery Systems , Membranes, Artificial , Polymers/chemistry , Porosity
3.
ACS Appl Mater Interfaces ; 7(19): 10401-6, 2015 May 20.
Article in English | MEDLINE | ID: mdl-25912512

ABSTRACT

The concept of a responsive nanoporous thin-film gel membranes whose pores could be tuned to a desired size by a specific "molecular signal" and whose pore geometry becomes "memorized" by the gel is reported. The ∼100 nm thick membranes were prepared by dip-coating from a solution mixture of a random copolymer comprising responsive and photo-cross-linkable units and monodisperse latex nanoparticles used as a sacrificial colloidal template. After stabilization of the films by photo-cross-linking the latex template was removed, yielding nanoporous structures with a narrow pore size distribution and a high porosity. The thin-film membranes could be transferred onto porous supports to serve as tunable size-selective barriers in various colloids separation applications. The pore dimensions and hence the membrane's colloidal-particle-size cutoff were reversibly regulated by swelling-shrinking of the polymer network with a specially selected low-molar-mass compound. The attained pore shape was "memorized" in aqueous media and "erased" by treatment in special solvents reverting the membrane to the original state.


Subject(s)
Membranes, Artificial , Nanopores/ultrastructure , Nanostructures/chemistry , Nanostructures/ultrastructure , Polymers/chemistry , Ultrafiltration/methods , Materials Testing , Porosity
4.
ACS Appl Mater Interfaces ; 7(23): 12463-9, 2015 Jun 17.
Article in English | MEDLINE | ID: mdl-25612328

ABSTRACT

The article describes a novel polymer blend system that yields thin films with unique porous nanoscale morphologies and environmentally responsive properties. The blend consists of sodium alginate and amine end-terminated PEG, which undergoes phase separation during film deposition. The blend films can be readily converted into highly porous membranes using facile treatment with a solution containing divalent ions. The resulting membranes are primarily comprised of alginate hydrogel, whereas the PEG phase is removed from the films during exposure to the saline solution, yielding nanometer-sized pores. The alginate gel phase forms a three-dimensional nanostructure which can be best described as a filament or fibrous network. Because such network geometry is untypical of polymer blends in thin films, possible reasons for the observed phase morphology are discussed. Because of ionizable carboxyl groups, the hydrogel membranes demonstrate responsive behavior, in particular a drastic change in their porosity between a highly porous state and a state with completely closed pores in response to changes in the solution pH. The pore-size tunability can be explored in multiple applications where the regulation of material's permeability is needed.


Subject(s)
Biopolymers/chemistry , Nanostructures/chemistry , Alginates/chemistry , Glucuronic Acid/chemistry , Hexuronic Acids/chemistry , Membranes, Artificial , Porosity , Surface Properties
5.
Langmuir ; 20(10): 4064-75, 2004 May 11.
Article in English | MEDLINE | ID: mdl-15969399

ABSTRACT

Smart surfaces can be described as surfaces that have the ability to respond in a controllable fashion to specific environmental stimuli. A heterogeneous (mixed) polymer brush (HPB) can provide a synthetic route to designing smart polymer surfaces. In this research we study HPB comprised of end-grafted polystyrene (PS) and poly(2-vinyl pyridine) (P2VP). The synthesis of the HPB involves the use of an "intermolecular glue" acting as a binding/anchoring interlayer between the polymer brush and the substrate, a silicon wafer. We compare anchoring layers of epoxysilane (GPS), which forms a self-assembled monolayer with epoxy functionality, to poly(glycidyl methacrylate) (PGMA), which forms a macromolecular monolayer with epoxy functionality. The PS and P2VP were deposited onto the wafers in a sequential fashion to chemically graft PS in a first step and subsequently graft P2VP. Rinsing the HPB in selective solvents and observing the change in water contact angle as a function of the HPB composition studied the switching nature of the HPB. Scanning probe microscopy was used to probe the topography and phase imagery of the HPB. The nature of the anchoring layer significantly affected the wettability and morphology of the mixed brushes.

6.
J Am Chem Soc ; 125(40): 12211-6, 2003 Oct 08.
Article in English | MEDLINE | ID: mdl-14519006

ABSTRACT

We report on a unique, very simple method of preparation of reactive membranes and nanotemplates with nanoscopic cylindrical channels on the surface of various inorganic and polymeric substrates. Well-ordered nanostructured thin polymer films have been fabricated from the supramolecular assembly of poly(styrene-block-4-vinylpyridine) (PS-PVP) and 2-(4'-hydroxybenzeneazo)benzoic acid (HABA), consisting of cylindrical nanodomains formed by PVP-HABA associates surrounded by PS. Alignment of the domains has been shown to be switched upon exposure to vapors of different solvents from the parallel to perpendicular orientation to the confining surface and vice versa. The alignment of the cylindrical nanodomains is insensitive to the composition of the confining surface due to the self-adaptive behavior of the supramolecular PVP-HABA assembly. Extraction of HABA with selective solvent results in nanomembranes with a hexagonal lattice (24 nm in the period) of hollow channels of 8 nm in the diameter crossing the membrane from the top to the bottom. The walls of the channels are constituted from reactive PVP chains. The channels were filled with Ni clusters via the electrodeposition method to fabricate the ordered array of metallic nanodots of 1.2 tera per cm(2).

SELECTION OF CITATIONS
SEARCH DETAIL
...