Preprogramming Floating Time of Liquid Marble

Non-sticking droplets wrapped with fine hydrophobic particles, namely liquid marbles, can be transported both on solid and water pool without an undesired spill of the inner encapsulated liquid. While the stimuli-responsive release of the inner liquid in the target area is proposed, the time-programmed release is not yet achieved. Herein, the hydrophobicity of nanoclay is modulated via a catalyst-free 1,4-conjugate addition reaction to form liquid marbles. This nanoclay liquid marble is robust and stable in air but collapses on the liquid pool with a specific lifetime. The lifetime of the liquid marble can be modulated over seconds to hours scale depending on the selection of chemically modulated wettability of the nanoclay. The critical mechanism of lifetime modulation is responsible for controlling the coalescence kinetics between the water pool and inner liquid by nanoclays’ high diffusion length and chemically varied water spreading potential. The NC liquid marble's programmable lifetime to ‘time-bomb’ type drug release and cascade chemical reaction is applied—without requiring any external intervention.     

Injectable polyethylene glycol-laponite composite hydrogels as articular cartilage scaffolds with superior mechanical and rheological properties

In this study, injectable PEG-based hydrogels containing Laponite particles with mechanical and structural properties close to the natural articular cartilage are introduced. The nanocomposites are fabricated by imide ring opening reactions utilizing synthesized copolymers containing PEG blocks and nanoclay through a two-step thermal poly-(amic acid) process. Butane diamine is used as nucleophilic reagent and hydrogels with interconnected pores with sizes in the range of 100–250?µm are prepared. Improved viscoelastic properties compared with the conventional PEG hydrogels are shown. Evaluation of cell viability utilizing human mesenchymal stem cells determines cytocompatibility of the nanocomposite hydrogels.     

The synergistic performance of multiwalled carbon nanotubes and sepiolite nanoclays as flame retardants for unsaturated polyester

The synergistic effect on the thermal decomposition and heat release rate (HRR) in particular the peak heat release rate (PHRR) of unsaturated polyester (UP) resin blended with multiwalled carbon nanotubes (MWNTs) and sepiolite nanoclay was investigated using thermal gravimetric analysis (TGA), pyrolysis combustion flow calorimetery (PCFC) and the cone calorimetery. Initial microcalorimeter findings established a synergistic effect for ternary system comprising a 10:0.5 wt% mixture of sepiolite:MWNT, respectively, which resulted in a 40% reduction in heat release capacity (HRC). This result was also confirmed within the well‐established cone calorimeter by a 50% reduction in PHRR in contrast to unfilled UP. The mechanism behind this reduction is thought to be due to the bridging of the MWNTs between the sepiolite clay needles, creating a tight protective surface layer that reduces the MLR. TGA also confirmed the advantage of such a ternary system through a 36^°C shift in the onset decomposition temperature and an 11% increase in residual char. Copyright © 2010 John Wiley & Sons, Ltd.     

Influence of maleated elastomer on filler dispersion,mechanical and antimicrobial properties of hybrid HDPE/clay/silver nanocomposites

This work analyses the effect of using ethylene-propylene-diene-monomer-grafted maleic anhydride (EPDM-g-MA) as compatibilizer to improve the interfacial properties and toughness of high-density polyethylene–organoclay–silver (HDPE/clay/silver) nanocomposites. EPDM-g-MA was reacted using ultrasound with a solution of AgNO₃ 0.04 M and ethylene glycol using ammonium hydroxide to obtain the silver ammonium complex. This silver-coated maleated EPDM was then melt mixed with HDPE and organoclay (Nanomer I28E) using a twin-screw extruder. Transmission electron microscopy (STEM) and X-ray diffraction (XRD) results confirmed the filler dispersion of both organoclay and silver nanoparticles into HDPE matrix when maleated EPDM was used. Both fillers were better dispersed and exfoliated by using this compatibilizer. The thermal stability enhancement of nanocomposites was confirmed using thermogravimetric analysis. Mechanical and antimicrobial properties demonstrated that better dispersed filler obtained with maleated EPDM enhanced the toughness and antimicrobial behaviour of HDPE/clay/silver hybrid nanocomposites. This confirmed that maleated EPDM was an efficient compatibilizer to obtain hybrid nanocomposites with enhanced properties to be used for several HDPE applications.     

The effect of nanoclay and MWNT on fire‐retardency and mechanical properties of unsaturated polyester resins

The influence of nanomaterials such as Multi‐Walled Carbon NanoTubes (MWNT) and organoclay (Cloisite 30B) on the physical and mechanical properties of thermoset matrix such as Unsaturated Polyester (UP) resins is investigated. Although styrene containing UP resins have a wide spread application in industry, lack of information exists regarding the behavior of MWNT/organoclay/polyester ternary nanocomposite systems. The main aim of this research was first to evaluate the effect of nanofiller on the flammability of UP resins and, second, to characterize their mechanical properties such as toughness and their tensile strength. The rheological studies showed shear thinning for samples of UP resins containing MWNT and Cloisite 30B. The cone calorimetry measurement was used to evaluate the flame‐retardency, the gas emission of the nanocomposite and whether or not this system can be designated as a nanocomposite. This was understood in the test by the peak heat release rate being lowered and shifted to shorter times. Furthermore, the tensile and impact properties of samples were evaluated. The obtained results indicated that nanofiller particles caused both increase and decrease in the impact and tensile strength. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Development of epoxy-cyanate ester-clay nanocomposites offering enhanced thermally stability

The preparation and characterization of blends of a series of dicyanate monomers such as 2,2′-bis(4-cyanatophenyl) propane (DCDPP), bis-4-cyanato-biphenyl (DCBP), bis-4-cyanatonaphthalene (DCN), 3,3′-bis(4-cyanatophenyl)sulphide (DCTDP), 3,3′-bis(4-cyanatophenyl)sulphone (DCDPS), and the diglycidyl ether of bisphenol A are reported. These copolymers are combined with a montmorillionite nanoclay and both epoxy-cyanate blends and epoxy-cyanate blends-nanoclay composites are all analyzed for thermal stability, thermal degradation kinetics, flame retardancy, and impact strength. The nanocomposites are further characterized by X-ray diffraction and SEM to determine morphological features, from which structure–property relationships are determined. Dispersion of the nanoclay is of paramount importance, but its inclusion serves to improve char yield and impact strength, when this is achieved. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47754.     

Capped inhibitor-loaded halloysite nanoclay-based self-healing silica coatings for corrosion protection of mild steel

The effect of polymeric nanocapsule capping in benzotriazole encapsulated into halloysite nanoclay (HNTs) dispersed into hybrid silica coatings was investigated for corrosion protection of mild steel. Optimization of the amount of inhibitor-loaded halloysite nanotubes with and without capping in the coating sol was carried out. The prepared formulations were dip-coated on mild steel substrates using dip-coater and then cured at 130 °C for 1 h. Surface morphology and elemental analysis of the nanoclay were studied using scanning electron microscopy and energy dispersive X-ray spectroscopy. X-ray diffraction and Fourier Transform Infrared spectroscopy analyses were carried out to confirm the encapsulation and capping of the halloysite nanoclay. The anti-corrosion and autonomic-healing properties of bare and coated substrates in 3.5 wt% NaCl solution were studied using electrochemical impedance spectroscopy, potentiodynamic polarization measurements and scanning vibrating electrode technique for varying exposure times. The coatings generated from the capped inhibitor-loaded HNTs dispersed sol-gel matrix was seen to provide higher corrosion resistance when compared to uncapped HNT based silica coatings. Electrochemical studies carried out for capped inhibitor-loaded HNT based coatings have shown an increase in charge transfer resistance to 10⁸ Ω cm² from 10⁶ Ω cm² of uncapped inhibitor-loaded HNT based coatings.     

Nanorobots Constructed from Nanoclay: Using Nature to Create Self‐Propelled Autonomous Nanomachines

Self‐propelled, autonomous micro and nanomachines are at the forefront of current nanotechnology. These micro and nanodevices move actively to perform desired tasks, usually using chemical energy from their surrounding environment. Typically, these structures are fabricated via clean room or template‐based electrodeposition methodologies, which yield relatively low numbers of these devices. To utilize these machines in industrial‐scale operations, one would need an inexpensive fabrication route for mass production of nanomachines. The use of naturally occurring nanotubes, Halloysite nanoclay, to fabricate functional nanomotors in great quantities is demonstrated. These nanotubes can be mined in ton quantities and used as base for the fabrication of nanomachines. In addition, it is well known that the surface groups of Halloysite nanoclay bind strongly with heavy metals, which makes it potentially useful in environmental remediation.     

House of Cards Nanostructuring of Graphene Oxide and Montmorillonite Clay for Oil–Water Separation

Noncovalent interactions are ubiquitous in our daily living. Nature employs hydrophobic effects, π–π interactions, hydrogen bonding, van der Waals forces, and electrostatic interactions in many biological processes such as protein folding. In the same manner, scientists exploit this plethora of inherently reversible noncovalent interactions as dials to design robust and smart materials. Electrostatic interaction is particularly interesting due to the simplicity of its concept, i.e., opposite charges attract. However, to our knowledge, the electrostatic interaction between two different 2D nanomaterials has not been investigated in literature. A myriad of natural and synthetic 2D nanomaterials should be explored for what may be an exciting cocktail of synergistic and tunable properties brought about by their charges and physical properties. This contribution highlights an interesting phenomena when organic, negatively charged graphene oxide and inorganic, positively charged montmorillonite (MMT) clay edges are brought into contact.