Polymer-based microreactors turn inorganic to beat organic solvent attacks and reduce prices.

Dong-Pyo Kim from the Chungnam National University, Daejeon, Korea, and colleagues used inorganic polymers to make microreactors that are resistant to attack by organic solvents and should be cheap to manufacture.

 

Microreactors can now be made from inorganic polymers which are resistant to attack by organic solvents

 

Microreactors are miniaturised devices where reactions take place within a confined space typically in the form of microchannels on a chip. They have a number of advantages over conventional reaction systems including yield, energy efficiency, reaction control and safety.

A variety of materials have been used to make microreactors, including metal, silicon, glass and polymers. However, while metallic and silicon-based devices are durable they are expensive to make. Conversely, polymer reactors are cheap to manufacture but prone to attack by organic solvents limiting their use. Now Kim's group has developed inorganic polymer microreactors which offer the best of both worlds.

The team made microreactors using two commercially available inorganic polymers - polyvinylsilazane and allylhydropolycarbosilane - and a well established micro-imprinting lithography technique. Kim believes this low-cost method could be used for mass production. Tests showed the microreactors are resistant to attack by a variety of organic solvents.

To create the microreactor, Kim dropped liquid inorganic polymer onto a glass slide under a nitrogen atmosphere. He then placed a stamp - with the microchannel in relief on its surface - into the polymer and cured it using UV light. The polymer solidified, and the stamp was removed leaving the impression of the microchannel. The polymer was then heat-cured before a second glass slide coated with the polymer was placed on top, enclosing the channel.

To demonstrate the performance of their new microreactors the team showed that they could be used to carry out three synthetic organic reactions - synthesis of 3,5-dimethylpyrazole, a Diels-Alder cycloaddition and a Knoevenagel condensation.

Kim is currently exploring ways to improve the fabrication process as well as looking at applying these microreactors in other fields such as biotechnology and biomedical engineering.

Nicola Burton