Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nanoscale factories built to order

03.11.2016

Performing chemical reactions inside tiny droplets can help manufacturers develop greener processes for coating drugs.

A discovery led by Singapore's Agency for Science, Technology and Research (A*STAR) could lead to improvements in the way drugs are delivered to the right parts of the body by uncovering the mechanisms that help oil, water, and free radicals mix in tiny droplets [1][2].


Understanding how radical fragments (red spheres) react with surrounding water molecules to create hydroxyl radicals, while leaving behind hydrophobic residues (black), can help green chemistry researchers. © 2016 A*STAR Institute of Chemical and Engineering Sciences

Emulsion polymerization is an emerging technology used to produce enormous chain-like molecules called polymers inside oil-filled drops suspended in water. This approach enables producers of goods such as latex paints to do away with traditional oil-based solvents, which helps them meet stricter environmental controls. Recently, researchers have discovered that ‘mini-emulsions’, in which droplets are shrunk to nanoscale sizes using powerful blenders and stabilized with fatty molecules, can produce nanoparticles for applications including controlled drug release.

Alex van Herk from the A*STAR Institute of Chemical and Engineering Sciences explains that in mini-emulsions, each droplet can be regarded as a ‘nanoreactor’ — a segregated system where all the ingredients for polymerization are present in one spot. Once a highly reactive free radical enters the drop, the small molecules inside link into chains. “The nanoreactors grow completely independently, and we can achieve very high reaction rates,” he says.

This polymerization only works when one free radical enters a nanoreactor. However, the molecules that generate free radicals, known as initiators, generally produce them in pairs. To better understand these radical movements, van Herk and colleagues from the Netherlands and the United Kingdom investigated the effects of using initiators that either repelled or attracted water molecules.

Typical initiators are water-soluble and researchers propose that they create pairs of free radicals in water where one of the free radicals enters the nanoreactor and starts the polymerization. However, when the initiator is a water-repelling molecule, such as lauroyl peroxide, theory predicts the chemical reaction will be hindered because the two radicals in a confined space would easily recombine and the polymerization process would not start.

Surprisingly, the A*STAR-led team found mini-emulsion polymerization proceeded rapidly and completely using lauroyl peroxide initiators. To explain this discrepancy, the team deduced that a free radical must leave by an alternative mechanism, known as chain transfer, which transforms one of the water molecules surrounding the nanoreactor into a hydroxyl radical compound. The remaining radical produces latex nanoparticles that correspond one-to-one with the initial droplet size — a benefit for manufacturers seeking to predict morphologies with exact specifications.

“Industry is only modestly adopting mini-emulsion polymerization, partly because its mechanism is not fully understood and controllable yet,” says van Herk. “These findings give us a better edge to design and produce special nanoparticle morphologies such as low-cost nanocapsules.”

The A*STAR-affiliated researchers contributing to this research are from the Institute of Chemical and Engineering Sciences. For more information about the team’s research, please visit the Polymer Engineering & Characterisation group webpage.

Associated links

Journal information

[1] Jansen, T. G. T., Meuldijk, J., Lovell, P. A. & van Herk, A. M. On the miniemulsion polymerization of very hydrophobic monomers initiated by a completely water-insoluble initiator: thermodynamics, kinetics, and mechanism. Journal of Polymer Science Part A: Polymer Chemistry 54, 2731–2745 (2016).
[2] Jansen, T. G. T., Meuldijk, J., Lovell, P. A. & van Herk, A. M. On the reaction characteristics of miniemulsion polymerization with aqueous phase initiation — Experiments and modeling. Macromolecular Reaction Engineering 9, 19–31 (2015).

A*STAR Research | Research SEA

Further reports about: A*STAR Nanoparticles Polymer free radicals polymerization water molecules

More articles from Life Sciences:

nachricht Novel methods for analyzing neural circuits for innate behaviors in insects
15.03.2019 | Kanazawa University

nachricht Converting biomass by applying mechanical force
15.03.2019 | University of Münster

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Revealing the secret of the vacuum for the first time

New research group at the University of Jena combines theory and experiment to demonstrate for the first time certain physical processes in a quantum vacuum

For most people, a vacuum is an empty space. Quantum physics, on the other hand, assumes that even in this lowest-energy state, particles and antiparticles...

Im Focus: Sussex scientists one step closer to a clock that could replace GPS and Galileo

Physicists in the EPic Lab at University of Sussex make crucial development in global race to develop a portable atomic clock

Scientists in the Emergent Photonics Lab (EPic Lab) at the University of Sussex have made a breakthrough to a crucial element of an atomic clock - devices...

Im Focus: Sensing shakes

A new way to sense earthquakes could help improve early warning systems

Every year earthquakes worldwide claim hundreds or even thousands of lives. Forewarning allows people to head for safety and a matter of seconds could spell...

Im Focus: A thermo-sensor for magnetic bits

New concept for energy-efficient data processing technology

Scientists of the Department of Physics at the University of Hamburg, Germany, detected the magnetic states of atoms on a surface using only heat. The...

Im Focus: The moiré patterns of three layers change the electronic properties of graphene

Combining an atomically thin graphene and a boron nitride layer at a slightly rotated angle changes their electrical properties. Physicists at the University of Basel have now shown for the first time the combination with a third layer can result in new material properties also in a three-layer sandwich of carbon and boron nitride. This significantly increases the number of potential synthetic materials, report the researchers in the scientific journal Nano Letters.

Last year, researchers in the US caused a big stir when they showed that rotating two stacked graphene layers by a “magical” angle of 1.1 degrees turns...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

A peek into lymph nodes

15.03.2019 | Medical Engineering

Novel methods for analyzing neural circuits for innate behaviors in insects

15.03.2019 | Life Sciences

Converting biomass by applying mechanical force

15.03.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>