‘Liquid marbles’ are a peculiar new substance made by rolling water droplets into powders incapable of dissolving in water. The resulting micro- and nanoscale-particles act like soft solids, and can speed along surfaces without leaving water marks.
Such non-stick, hydrophobic behaviour has potential application in drug-delivery and microfluidic technology. However, liquid marbles suffer from erratic structures prone to collapse. Jia Min Chin, Jianwei Xu and co-workers from A*STAR’s Institute of Materials Research and Engineering, and Institute of Bioengineering and Nanotechnology, have now developed a scheme to stabilise liquid marbles quickly and safely using vapours from ordinary superglue.
Many powders used to make liquid marbles are based on metal–organic frameworks (MOFs), a type of crystal in which metal ions are interspersed with rigid organic molecules. Chin, Xu and co-workers investigated whether MOFs known as NH2-MIL-53(Al), a combination of aluminium atoms and amino-phenyl compounds, could grow directly on the surfaces of alumina micro-particles.
This approach, the team theorised, might provide extra structural control over liquid marble stability. After confirming MOF growth with x-ray measurements, the team modified the micro-particles with either hydrocarbon or fluorocarbon chains, converting them into ‘superhydrophobic’ powders. Then, they produced alumina-supported liquid marbles by adding micro-sized water droplets.
The researchers found that their new liquid marbles had greater stability than usual, thanks to its reactive amino groups and high surface roughness. Yet, they sought to further boost its resilience. When they spotted small gaps between the MOF–alumina micro-particles with scanning electron microscopy, they inferred that certain gas molecules might enter these pores and create a cross-linked network through a process called air–liquid interfacial polymerisation.
Forensic scientists often use superglue vapours to uncover fingerprints at crime scenes; the trace water in finger smudges reacts rapidly with adhesive fumes and generates visible polymer structures. Taking a cue from this method, the team exposed their MOF–alumina liquid marble to superglue vapours in a Petri dish and saw a rigid polymer casing form within a few minutes. Chin notes that this procedure requires no heat, UV radiation, or chemical initiators — an unprecedented finding for liquid marble encapsulation. “Furthermore, the only solvent required was water, qualifying this as a ‘green’ reaction,” she adds.
The liquid marble retained its unique non-wetting behaviour on surfaces, even with the protective polymer coating. These stabilising attributes promise big dividends in areas such as gas purification and personal care products: two patents have already been filed this year in efforts to commercialise this technology.
The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering and the Institute of Bioengineering and Nanotechnology
 http://dx.doi.org/10.1039/c2cc37081fAssociated links
Nagoya University researchers break down plastic waste
29.05.2017 | Nagoya University
A new tool for discovering nanoporous materials
23.05.2017 | Ecole Polytechnique Fédérale de Lausanne
The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.
The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
29.05.2017 | Earth Sciences
29.05.2017 | Life Sciences
29.05.2017 | Physics and Astronomy