Interfaces and surfaces are where the action happens. Catalysis, molecular recognition, charge transfer, polymerization and many other critical processes take place at the boundary between one medium and another. With the need to integrate new materials into devices, and applications ranging from catalysis to sensors, medicine to self-cleaning surfaces, and displays to lasers, fundamental and applied studies of surface and interface processes and optimization are of critical importance in developing new technology to meet today's challenges. The selection of recent research articles presented below illustrates the vast potential of this field.
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Monitoring the interfacial world: A new in situ imaging technology capable of selectively highlighting interfacial self-assembly in real time was developed by employing the unique photophysical properties of aggregation-induced emission (AIE). Application of this technology enabled direct high-contrast visualization of microemulsion evolution, “coffee-ring” formation, and breath-figure dynamics by fluorescence microscopy.
Spatial correlation of defects: Oxygen vacancies (VO), the dominant surface defects at TiO2(110), are absent in the vicinity of positively charged subsurface point defects. These point defects, in turn, are located only beyond the nearest subsurface region, which is thus void of any charged defects (see figure).
A mild photochemical approach was applied to construct highly coupled metal–semiconductor dyads (example in picture: carbon nitride), which were found to catalyze the hydrogenation of nitrobenzene. Aniline was produced in excellent yield (>99 %, TOF 1183) using formic acid as hydrogen source and water as solvent at room temperature. This process is applicable to a many nitroarenes without the involvement of high-pressure gases or sacrificial additives.
Nuked for control: Silver nanoparticles deposited on CeO2-SBA-15 supports possess tunable particle sizes and metal–support interactions (MSIs) when prepared by microwave (MW) irradiation owing to the strong charge polarization of CeO2 clusters (i.e., MW absorption; see figure). The Ag nanoparticle size and MSIs were responsible for the high turnover frequency numbers in ammonia borane dehydrogenation and 4-nitrophenol reduction.
Gold nanostars: The relationship between the enhancement by surface-enhanced Raman spectroscopy (SERS) and the localized surface plasmon resonance (LSPR) band is investigated (see picture). The competition between the field enhancement and the optical extinction causes the maximum enhancement factor occurring at a blue-shifted LSPR band from the excitation wavelength rather than at the on-resonance position.
More functional: The surface modification of mesoporous silica monoliths through thiol–ene chemistry is reported (see figure). Mesoporous silica monoliths with vinyl, allyl, and thiol groups were synthesized through a sol–gel hydrolysis–polycondensation reaction The different reactivity of the vinyl and allyl groups on the pore wall affects the addition reaction, and hence, the degree of the pore-wall functionalization.
Going far: Long-distance charge transport is synthetically accessible from double-channel systems, but not from ion-gated or from triple- or single-channel photosystems with central perylenediimide stacks. Hole- rather than electron-transporting perylenediimides and maximized charge separation rather than minimized charge recombination give the best activities (see picture).
Taking shape: A Ru3+-mediated synthesis has been developed for unique Pd concave nanostructures which can directly harvest UV-to-visible light for styrene hydrogenation (see figure). The catalytic efficiency under full-spectrum irradiation at room temperature turns out to be comparable to that of the thermally (70 °C) driven reaction. The yields are higher than those obtained using Pd nanocrystals such as nanocubes and octahedrons.
Caught on camera: NaGdF4 nanoparticles coated with ethylenediaminetetraacetic acid (EDTA) chelators functionalized with organic moieties and luminescent dyes were prepared and characterized, and their potential as dual probes for optical/magnetic resonance imaging (MRI) imaging was investigated (see figure).
Sensing Sensibility: A macrocyclic dibenzocoronene tetracarboxdiimide containing two benzo-21-crown-7 groups has been synthesized. It shows liquid-crystalline behavior and selectively binds Pb2+ or K+ to form 1:2 complexes in solution. The complexation leads to a significant increase in fluorescence. The surface organization of discotic columnar structures, in the solid-state, can be controlled by selective ion binding.
Hold the foam: A surface nanobubble-based diffusion mechanism is proposed that accounts for bubble generation during polymeric foaming in the presence of dispersed nanoparticles. Estimated final bubble sizes in foam are compared with experimentally determined foam morphologies. This simple continuum model gives good agreement between theory and experiment, and can also predict the large difference between nucleating efficiencies of nanoparticles in reactive and nonreactive foaming.
Efficient and generic enantioselective discrimination of various chiral alcohols is achieved by surfaced-enhanced Raman scattering (SERS) spectroscopy. This approach is label-free, does not employ any chiral reagents, and may lead to the development of novel enantiosensing strategies.
Cleaner water: Bubble formation at the water–organic solvent interface is dependent on the pH of the medium and the concentration of graphene oxide present. Graphene oxide nanosheets are utilized as carriers for the reactive extraction of methyl green and methyl blue dyes from the aqueous to the organic phase with extraction efficiencies of up to 98.2 and 83.6%, respectively.
The transfer of vibrational energy in collisions of an NO molecule with a gold surface proceeds by electron transfer. Thanks to new optical pumping and orientation methods, all molecular degrees of freedom important to this process can be controlled. The probability of the electron-transfer reaction is enhanced by increased translational and vibrational energy as well as by proper orientation of the reactant.
A hive of activity: Tuning the near-surface composition of Ru and Ir elements in a bimetallic oxide by surface segregation results in the formation of a nanosegregated domain (see picture) that balances the stability and activity of surface atoms. A Ru0.5Ir0.5 alloy prepared by this method exhibited a stability four-times higher than the best Ru-Ir oxygen evolution reaction materials, but the same activity.
Understanding hydrogenation on transition metals: Subsurface hydrogen, Hsub, is shown to significantly influence the stability and the reactivity of the adsorbed hydrogen in two different ways. Calculations on a representative reaction, ethyl hydrogenation, show that it is accelerated on Pd and Pt, but slowed down on Ni and Rh in the presence of Hsub.
Needle in a haystack: A chip-based electrochemical assay using metal nanoparticles (MNPs, see picture) allows simultaneous detection of multiple different biomarkers on the surfaces of cancer cells, enabling discrimination between cancer cells and normal blood cells. As few as two cells captured per electrode can be detected.
Multifunctional CPPs: Robust and biocompatible coordination polymer nanoparticles (CCPs) with enhanced thermal and colloidal stabilities were obtained by incorporation of carboxyl groups on the amorphous structure. The surface carboxyl groups can be subsequently functionalized, generating a multifunctional nanoplatform for theranostic applications such as drug delivery and imaging.
Riding on the surface states highway: First-principles calculations and photoelectrochemical measurements provide a framework for deepened understanding of the oxygen evolution reaction from water splitting on hematite. The reaction takes place on the O-terminated hematite surface via surface states close in energy to the top of the valence band.
Reversible phase transfer: Octadecyltrimethoxysilane (ODTS) has been used to cap the surfaces of hydrophilic magnetic nanoparticles (NPs), thereby allowing their transfer into nonpolar solution. The resulting hydrophobic magnetic nanoparticles were transferred back into aqueous solution by covering them with a lipid monolayer (see figure; Egg-PC=egg yolk phosphatidylcholine).
Capillary foams are a new class of foams, in which particles and a secondary liquid jointly adsorb at the surface of gas bubbles within a bulk liquid. Particles that adsorb preferentially at the interface of the secondary liquid can mediate its spreading around the gas bubbles. The bubbles are further entrapped in a network of excess secondary-liquid-bridged particles in the primary liquid.
On the surface: The thermal decomposition of organometallic complexes with N-heterocyclic carbene ligands affords Pt nanoparticles that are soluble and stable in water for an indefinite period. The 13C–195Pt coupling observed by solid-state NMR spectroscopy confirms carbene coordination to the nanoparticle surface.
Liquid, solid, or gel? High-performance electrolytes are important for the success of advanced energy-storage devices. From the view of battery structures and the electrolyte, this Review not only summarizes and discusses the up-to-date development of various electrolyte materials (liquids, solids, and gels), but also emphasizes a comprehensive understanding of electrolyte properties, which is critical for the design of high-performance electrolytes.
Like oil and water: Superoleophobic surfaces with tunable adhesion were obtained by assembling mixed carboxylic acid on nanostructured aluminum substrates. The surface adhesion can be controlled by simply controlling the surface chemical composition (see figure).
Cu-trimer nodes: Using scanning tunneling microscopy and X-ray photoelectron spectroscopy, tetrahydroxybenzene (THB) is shown to dehydrogenate when adsorbed on a Cu(111) surface and form a highly reactive ligand. Density functional calculations confirm that the ligand stabilizes copper adatom trimers and creates a surface coordination network that is a two-dimensional analogue of metal–organic frameworks.
The ferrocene-terminated Si (Si-Fc) as diodes: The diode nature of Si-Fc samples is attributed to the existence of a potential barrier between the Si substrate and the ferrocene layer. The diode nature of Si-Fc samples can be associated with some of its characteristics, such as the dependence of its cyclic voltammetry response on types of substrate and illumination.
Nanoparticle functionality: Iron oxide nanoparticles are functionalized by protected functional siloxanes. The functional group is deprotected on the nanoparticle itself, solving multiple issues related to the use of siloxanes. This procedure is highly reproducible and not limited to the discussed functionalities.
The long and short of it: A Au surface is modified by in situ reduction of aryldiazonium salts, and single-stranded DNA is covalently linked to the surface. A study of interactions of human Rad51 protein with DNA indicated that the presence of ADP promotes elongation of the Rad51 filament, whereas BRC4-28 peptide inhibits filament assembly.
Fluorescent nanomaterials: A one-step hydrothermal method to synthesize intercrossed carbon nanorings (see picture) with relatively pure hydroxy surface states is reported. The hydroxyl surface states make it possible to overcome aggregation-induced quenching effects and to emit scarce stable yellow-orange luminescence in both colloidal and solid states.
Staying on tip: RGD–Integrin binding in intact cell membranes is detected using controlled plasmonics between a cyclic-RGD peptide functionalized nanoparticle and a TERS tip. The observed TERS signal from the nanoparticles on cells matches the surface enhanced Raman signal for the purified αVβ3 Integrin receptor, demonstrating the selectivity. This enables the characterization of receptor binding in intact cell membranes.
Nanotube-based organic photovoltaics: An easily dispersible multiwalled carbon nanotube (MWCNT) derivative is prepared, and provides a platform for the synthesis of the phenyl butyric acid methyl ester derivative. Subsequently, pristine MWCNTs and the amide and ester derivatives are studied to provide an insight into influence of nanotube morphology on photovoltaic characteristics.
Electrolytic spray deposition was employed for the formation of nanoparticle spots on various substrates in air. These materials are rugged, versatile substrates for surface-enhanced Raman spectroscopy, in which they lead to good enhancements. Lithographic applications of this method of ion deposition were also investigated.
Interfacing: Stabilizing the surface of lithium metal is an important challenge that must be overcome to enable lithium–air or lithium–sulfur batteries to succeed. Controlling the interface between the electrolyte and lithium is thus critical. By attaching vinyl-containing silanes to the hydroxy-terminated surface of lithium metal, a critical functional group is introduced at this interface that can be used to tailor this critical interaction (see figure; scale bars: 500 μm).
Enzymes and electrodes in sync: Modification of carbonaceous electrodes with mediators with the appropriate redox potential, and a fast electron-transfer rate, creates an “electron sink” on the electrode surface. This effect pulls electrons from the cofactor, increasing the electron-transfer rate and generating higher current densities.
Spiky and hollow: By using Ag nanospheres as seeds, hollow Ag–Au nanodendrites can be prepared in 15 s by a combination of a galvanic replacement reaction between Ag and AuCl4−(aq), and a AuCl4−(aq) reduction using hydroquinone in the presence of polyvinylpyrrolidone (PVP) in water. Owing to their sharp tips, the Ag–Au nanodendrites were effective substrates for surface-enhanced Raman scattering (SERS) detection of 4-mercaptopyridine and rhodamine 6G.
Si prefers alcohol: Low-temperature hydrosilylation led to a preferential surface grafting of the Si-O-C linkage instead of the classic Si-C linkage when reacted with an alcohol carrying a short bifunctional alkyne (see figure). Even in the presence of another alkyne competitor (trifluoroalkyne) at equimolar concentration, the Si-O-C bond remained the dominant linkage to the silicon surface through nucleophilic reaction.
Explosive sensing: A structural mechanism that takes into account both the special conformation of oligophenyleneethynylene molecules at a thin-film surface and antenna effects enabled by exciton migration is presented (see figure). This mechanism explains why these crystallized fluorescent films exhibit excellent sensing properties toward nitroaromatic vapors despite the fact that they are nonporous.
To nano or not to nano? Assessment of the mixing thermodynamics and the effect of the particle size on Fe-Ti spinel oxides leads to an intriguing conclusion about the heats of mixing on both macro and nanoscale. The energetics of the nanosized spinel oxides turn out to be predictable based only on knowledge of their macroscale energetics and surface energies, which are consistent regardless of composition. The findings have important implications for designing nanoscale spinel oxides with desirable properties.
Two birds with one stone! Xanthates and peroxides are used as radical precursors to graft various functions at the reduced graphene oxide surface. The developed method allows a double functionalization by both xanthate and peroxide radicals to be performed in one single step. The versatility of the method is highlighted by the grafting of seven xanthates and four peroxides. The resulting material shows no visible structural damage and long-lasting dispersibility.
Sourcing luminescence: Imidazolium–silica-based nanoparticle networks (INNs) have been synthesized and characterized (see picture). A molecular model for the imidazolium–silica network is presented and described. The presence of water near the silica surface and its influence on the position of the counteranions in the INN has been shown.
Less is more: Pt–Pd–graphene stack structures (see picture) are prepared by a new method that allows control of the thickness of the Pt shell. This thickness correlates with performance in the hydrogen evolution reaction (HER). As a result of surface polarization, the HER activity actually increases with decreasing Pt thickness, opening possibilities of using less Pt.
Combined experimental and theoretical approaches resulted in a better understanding of the hydrogenation of CO2 to methanol on copper-based catalysts. These results highlight the important role of the reducible oxide promoter for CO2 activation.
Friction force fluctuation and tribocurrent generation at metal–insulator interfaces show a strong correlation during sliding contacts. The reported results suggest that these two phenomena have a common origin that must be associated with the occurrence of strong electrostatic interactions at the interface.
Making changes with visible light: Recent developments in the direct photocatalysis of plasmonic-metal nanoparticles are described, with a focus on the role of the localized surface plasmon resonance (LSPR) effect in plasmonic metals and their applications in organic transformations (see figure). The role of light irradiation in the catalyzed reactions and the light-excited energetic electron reaction mechanisms will be highlighted.
Pick and choose: A three-step strategy for synthesizing Ag-MS (M=Zn, Cd) nanoheterostructures by following a solution–liquid–solid (SLS; see figure) mechanism with Ag2S nanoparticles as catalysts, followed by conversion of Ag2S sections of the heterostructures into silver nanoparticles by selective extraction of sulfur, is reported.
Sub-monolayer photochemistry: A Tetraphenylporphyrin derivative carrying para-amino-phenyl functional groups is used to obtain extended and highly ordered molecular wires on Ag(110) through a photochemical approach. A low-to-high density approach is used in order to not sterically prevent the conformational adaptation of the molecules during the reaction (see figure).
Rapid and universal coatings were developed from mussel-inspired dendritic polyglycerol that mimics mussel foot proteins with regard to functional groups, molecular weight, and molecular structure. Multiple further modifications can be achieved by either pre- or post-functionalization and control of surface roughness.
The subunit stoichiometry of archaeal RNase P, a multi-subunit ribonucleoprotein complex, was determined by surface-induced dissociation coupled with ion mobility mass spectrometry. Native MS studies with the proteins showed RPP21·RPP29 and (POP5·RPP30)2 complexes, but indicated a 1:1 composition for all subunits when either one or both protein complexes bind the cognate RNA.
It makes sense: Anion transfer for highly hydrophilic phosphate and hydroxide anions into a water-immiscible organic phase is driven with a manganese(II/III) redox system and facilitated with a hydrophobic oil-based boronic acid. It is shown that phosphate transfer is facilitated by boronic acid. Improved boronic acid facilitators and nanotrench electrodes are discussed in terms of future feasibility for phosphate sensing applications.
A strong effect: The controversy over vibrational properties of sulfate adsorption on Pt(111) surface originates from the different adsorption models in use. Ab initio molecular dynamics simulations employing different models yield a unified interpretation for various experimental and simulation results. The model (right side) that best approximates the experimental environments reproduces the experimentally observed Stark effect.
Controllable bioelectrocatalysis: The reversible activation of bioelectrocatalysis by external stimuli at stimuli-responsive supramolecular interfaces integrated with redox enzymes has been established, allowing potential applications in controllable biofuel cells, biosensors, bioelectronic devices, and for energy transduction and information storage. This Minireview outlines the current knowledge and important trends in this area.
Self-reduction: A general route for the direct growth of metal particles on TiO2 nanosheets with (001) exposed facets by an oxygen-vacancy-driven self-redox reaction is reported. Because there is no need for thermal treatment to remove stabilizing agents, the structure of the nanoparticles can also be retained, preserving the active sites associated with the high activity (see scheme).
Atomic cartography: Atom-probe tomography reveals the atomic structure of Au@Ag nanoparticles. The atomic arrangement of the particle is reconstructed with a resolution of ±0.5 nm and shows that the surface coverage of Ag is influenced by the presence of residues from the synthesis. There is also a relationship between the particle's surface curvature and the Ag surface coverage (surface excess, ΓAg).
A core–shell nanostructure with three distinct components enables the efficient production of H2 from water and significant electron harvesting under visible-light irradiation because of enhanced hot-electron injection, the formation of a Schottky junction, and high-performance electron filtering. The electron transfer pathway is elucidated through steady-state and time-resolved photoluminescence spectroscopy.
Supercharged capacity: For the first time, a facile and efficient method for the preparation of a 3D graphene/carbon composite is described with a superhigh surface area of 2034 m2 g−1 and a hierarchical pore texture, resulting in excellent capacitive performance (see figure).
Choosing a position: The controlled formation of hydrophobic fibers by careful choice of the position of the hydrophobic substituent has been achieved. The 3-position of 3,4-propylenedioxythiophene is the best to preserve the presence of nanofibers when a voluminous substituent is introduced, owing to longer polymer chains and higher hydrophobicity (see figure).
Bacterial imprinting at interfaces: Using bacteria as both emulsion stabilizers and microbial templates, bacteria-imprinted sites are produced on polymer beads, which can facilitate microbial assembly on the surface. During the imprinting, the pre-polymers that match the target cell surface can be preferentially selected.
The ratio of NMR relaxation times, T1/T2, can provide a unique probe of adsorbate–adsorbent interactions in liquid-saturated porous materials (see figure). This method has been used to study the interaction of water with a range of oxide surfaces (TiO2 anatase, TiO2 rutile, γ-Al2O3, SiO2, &thgr;-Al2O3 and ZrO2).
Solar power: Silver-decorated porous TiO2 nanofibers (NFs) with high surface area, enhanced light scattering, enlarged interpore connections between the NFs in a photoanode film, and localized surface plasmon resonance (see figure) result in an improved power conversion efficiency in dye-sensitized solar cells from 6.2 to 8.8 % (42 % enhancement) relative to pure TiO2 NFs.
Tunnel vision: Recent progress in applying scanning tunneling microscopy (STM) manipulations to regulate the inter-adsorbate and adsorbate–substrate interactions on solid surfaces is reviewed (see figure). This technique has demonstrated a versatile and general method to not only differentiate intermolecular interactions but also construct molecular nanostructures by regulating the adsorbate interactions.
Co-condensation between benzene-1,3,5-tricarbaldehyde and p-phenylenediamine on a graphene surface leads to a surface covalent organic framework (COF) with single-layer thickness. Strong coupling between the surface COF and graphene was confirmed by the significant mixing of states and the relatively large interaction energy revealed by STM and DFT simulation.
Nanoparticles and macrocycles: Recent literature regarding the combination of supramolecular macrocycles and metal nanoparticles is reviewed, with particular emphasis on the synthesis, surface modification and assembly, as well as the potential applications of the obtained nanocomposites (SERS = surface-enhanced Raman spectroscopy).
Nanoparticles and reactive surfaces: This Minireview provides an overview of selected CO-induced nanostructuring (see scheme). Recent examples of metal-surface and nanoparticle restructuring as a consequence of exposure to CO are discussed and show that nanoscale structures can be obtained under fairly mild conditions. Several cases of mono- and bimetallic compounds are described that show a range of behaviours in relation with the metal–CO interaction strength.
Shine a light on your chemistry! This paper gives an overview of the reactive transient species that are produced in surface waters by sunlight irradiation of photoactive molecules (photosensitizers), such as nitrate, nitrite, and chromophoric dissolved organic matter (CDOM) (see scheme). The main transient species (.OH, CO3−., 1O2, and CDOM triplet states) are involved in the indirect phototransformation of a very wide range of organic pollutants in surface waters.
Down to the last detail: Nanostructured solid catalysts were already known in the early 20th century, but their exact structure was unclear. Nowadays, the arrangement of atoms and particles in solids can be manipulated and analyzed down to the atomic scale (see image). The use of specific highly active catalysts enables industrially relevant reactions to be performed at room temperature.
Diffraction at hard work: Modern heterogeneous catalysis would benefit from a multiscale science approach bridging the molecular world with the macroscopic world. Because of recent breakthroughs in X-ray diffraction methods, including the surface X-ray diffraction of atomically flat model catalysts, X-ray diffraction tomography of catalyst bodies, and X-ray profiling of an active catalyst in a chemical reactor, such an approach is now within reach.
Stick or twist: Recent progress in biointerfaces based on smart-responsive molecules or surface topographies has led to efficient approaches for controlling the adhesive behavior of bacteria.
Polishing up the crystal glasses: An overview of the preparation and characterization of ordered silica films on metal supports is reported. In particular, the specific case of a silica bilayer, which exists in a crystalline and a vitreous variety, is discussed and a model of the vitreous silica structure proposed by William Zachariasen in 1932 is verified. Beyond this, the possibility to prepare the crystalline and the glassy structure on the same support leads to the study of the crystal–glass phase transition in real space (see figure).
The importance of the chemical history of the electrode surface before electrochemical cycling as well as the correlation between interface phenomena, the formation/evolution of an interphase, and the electrochemical behavior of LiFePO4 and LiNi1/2Mn1/2O2 electrodes are investigated by magic-angle-spinning nuclear magnetic resonance, electron energy loss spectroscopy, and X-ray photoelectron spectroscopy. These techniques allow the study of interface aging and failure mechanisms.
Not just scratching the surface: Covalently attached monolayers on oxide surfaces are reviewed with an eye to improved robustness, increased functionalization, understanding structural details, and the resulting potential for applications. Such monolayers, provided they are robust enough, provide a way of improving the properties of the bulk oxide material.
Expanding vibrational spectroscopy: Since its first observation in 1973, surface-enhanced Raman scattering (SERS) has developed into a mature vibrational spectroscopic technique. The number of applications in chemistry as well as the material and life sciences is increasing rapidly. This Review summarizes the key concepts behind SERS and provides an overview of current applications in chemistry.
Porefection: Electrochemical transducers based on single stimuli-responsive polymeric nanopores can support a complete set of logic functions. Thermal, chemical, electrical, and optical stimuli are the input signals required to externally tune the pore conductance (i.e. the logical output).
Core of the matter: Key processes in nanostructured dye-sensitized solar cells (DSC) occur at material interfaces containing, for example, oxides, dye molecules, and hole conductors (see picture). The implementation of X-ray-based spectroscopic methods for atomic-level understanding of such properties is reviewed. Examples include energy matching, binding configurations, and molecular orbital composition.
Revealing electrochemistry: Key issues related to the electrochemistry of nanoparticles are being uncovered through innovative techniques capable of relating activity and structure, ultimately at the level of a single nanoparticle. Recent advances in experimental approaches are discussed and assessed, with particular emphasis on those that enhance the fundamental understanding of electrocatalysis and nanoscale electrochemistry.
High in fiber: Carbon fibers (CFs), which are widely utilized in fields ranging from fundamental research to industry, can be functionalized by both thin-layer coating and nanoparticle immobilization (see scheme). In this Minireview, these techniques and some practical applications of functionalized CFs, such as carbon fiber reinforced plastic (CFRP), are overviewed after briefly describing the basic properties of CFs.
Rational design at the nanoscale: Covalent assembly of molecular building blocks is a promising strategy to obtain functional nanostructures in one and two dimensions. This Concept article discusses how computational modeling could be used to obtain design rules that will advance this field towards the predictive design of specific functionalities on specific surfaces (see figure).
To expand the utilization of cellulose beyond its traditional uses, it is necessary to modify the surface of the fibers. This paper summarizes the modification of cellulose by controlled polymerization methods such as ATRP, RAFT, ROP, and ROMP. The combination of the excellent properties of cellulose with functional polymers creates new materials of great potential in advanced material applications.
In this review, a brief introduction to surface modification using poly(N-vinylpyrrolidone) and its copolymers and their potential biomedical applications is presented. Some perspectives on future research in the areas are also discussed.