We converse to Professor of Polymer Physics Eugene Terentjev, at the College of Cambridge, about the long term of plastic
Professor Terentjev is also included with Cambridge Smart Plastics, a start-up that makes an attempt to funnel leading polymer skills into revolutionising commodity plastics, accelerating innovation and engineering translation.
1. Which possible investigation application for polymer physics are you most psyched about, with Cambridge Clever Plastics?
“At the minute, we are most centered on what we feel is a real looking goal of ‘reversible adhesive tape’, designed jointly with Lohmann GmbH – the Europe’s greatest producer of adhesive and damping tapes. The ‘Holy Grail’ of adhesive know-how is a reversible adhesive that leaves no residue on the surface: a procedure that could have its ‘stickiness’ switched on and off on need.
“It turns out that liquid crystalline elastomers (LCEs) give just this features, switching its floor adhesiveness off on gentle heating, and reversibly recovering it on return to ambient temperature. Our present travel is to maximise the toughness of adhesiveness in the ‘on’ state, master how to incorporate the LCE into the Lohmann output line of roll-to-roll tape bonding. We hope that in executing this we would also have an understanding of the market place better, and ideally obtain other niches where by reversible adhesion is desired.
“The precise purpose why this reversible adhesion is a residence of LCEs is the anomalously enhanced damping of mechanical strength in these elements. Counter to intuition, it is much less the chemical nature of the surface that potential customers to ‘stickiness’, but extra the sturdy vibration damping of the bulk: e.g. the supplies that have higher vibration acoustic damping are constantly sticky, and the types that are not damping (like glass or strong plastic) are not sticky, even although the surface area chemistry may be the exact.
“Vibration damping qualified prospects to a second raft of apps that Cambridge Sensible Plastics develops (whilst we have to prioritise the effort and hard work, becoming a micro-size business). Now our major emphasis in this area (apart from introducing the damping characteristic to the adhesive tapes talked about above) is a small-volume substantial-value methods like hand-held vibrating ability applications, these types of as dental drills, or high-finish sporting activities devices these types of as gold golf equipment. We get the job done with the Cambridge University i-Teams Company Programme to create contacts with the end-user industry and much better healthy their demands.
“The lengthier-phrase application that we are pretty thrilled about, but which is presently on keep since the available funding pushes us in other instructions, is the thought of converting the mixed recycled plastic into a new material that we phone ‘Plastic 2.0’ which would have as good attributes as the originally created pure plastics – therefore would get rid of the need to have to develop additional (and would motivate the recyclers change their squander streams into worthwhile structural materials as a substitute of incinerating it).
“The principle relies on the similar core engineering of Cambridge Clever Plastics, which is the dynamic exchange of covalent bonds concerning polymer chains, which makes it possible for the crosslinked polymer networks (which would usually be regarded as non-recyclable insoluble thermosets) to change to a plastic circulation regime, hence allowing (re)processing – extrusion, injection of blow moulding, 3D printing, and critically: warmth welding.
“Especially the welding, which generally has quite minor good results in plastics – but is a essential function of Plastic 2., would enable lots of industrial processes of ‘additive manufacturing’ to come into play for this plastic.”
2. With the liquid crystal elastomers you are doing work on, you say that there is potential to label them as a new point out of make a difference. Can you explain to us more about this?
“Our early critique report, with Mark Warner, was called just that: “Nematic elastomers – a new state of matter”. The position is that everybody understands the “states of matter” as: gasoline – when the content expands uniformly to fill all offered quantity, liquid – when the product keeps the continuous density (i.e. incompressible, not like the gas), but is totally free to stream with no resistance to variations of its condition, and good – when the material (of a frequent density similar to liquid) resists elastically to any alter of its form, by what is referred to as the ’shear modulus’. So a block of strong will sit on the desk keeping its shape versus gravity, but when molten into a liquid – it will yield to gravity absolutely and circulation into the cheapest out there cavity, and when evaporated into a gas – will fill the total home with uniform low density.
“Liquid crystal elastomers occupy a ‘niche’ concerning solids and liquids. They are certainly ‘solid’ since an LCE would hold its condition as any piece of rubber we are familiar with. But specific geometries of shear deformation experience no resistance – a little something we have termed the “soft elasticity”, and the material appears (behaves) as liquid for these unique deformation modes.
“Soft elasticity is truly the origin of huge mechanical damping of LCEs – for the reason that deformations in these modes are only resisted by inside viscous dissipation, and direct to the reduction of elastic power travelling through these types of a medium. And, of training course, the adhesion that is the consequence of enhanced damping, is also the consequence of this gentle elasticity, or the ‘new condition of matter’ characteristic.”
3. Next on from that, what long run do you see for photograph-actuation in particular? I know artificial muscular tissues are in their early levels, but the sci-fi-esque options for healthcare are truly fascinating.
“Reversible mechanical actuation is a very impressive feature of LCEs it’s typically induced by heating/cooling cycles, but LCEs could also be manufactured delicate to mild and e.g. uniaxially deal on illumination (and increase again in the dim). We have dreamed of artificial muscles for more than 20 years, but so significantly this is not a reasonable prospect for muscle mass motion, for many reasons – for instance, it is tough to present area stimulus of higher enough depth, the mechanical response is generally gradual (very good for adaptation, but a lot less useful for quickly muscle action), and until just lately it was hard to produce LCE in related styles and in enough power to make a handy large-scale application.
“For these motives, Cambridge Intelligent Plastics is not pursuing commercialization of LCE actuation, even while we have numerous lengthy-distant tips. This exploration is continue to in the tutorial exploration stage and is completed in our Cambridge College laboratory. Right here we produce tremendous-potent LCE double networks, study to 3D print and extrude skinny aligned LCE filaments and weave textile from them, or check out huge-scale equipment these kinds of as our modern do the job on Heliotracker.
“For instance, we hope that the artificial muscle mass could be assembled from a bundle of LCE filaments, significantly like the genuine muscle mass construct of fibres, due to the fact it is considerably more quickly to supply the stimulus to a extremely skinny LCE item (the Heliotracker normally takes numerous minutes to answer to the change of light-weight problems mainly because its LCE actuators are thick and solid).”