{"id":2983,"date":"2019-03-29T17:31:02","date_gmt":"2019-03-29T08:31:02","guid":{"rendered":"http:\/\/163.180.4.222\/lab\/?p=2983"},"modified":"2019-03-29T17:31:02","modified_gmt":"2019-03-29T08:31:02","slug":"refrigeration-based-on-plastic-crystals","status":"publish","type":"post","link":"https:\/\/biochemistry.khu.ac.kr\/lab\/?p=2983","title":{"rendered":"Refrigeration based on plastic crystals"},"content":{"rendered":"<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<h5>Materials called plastic crystals have been found to undergo huge temperature changes when subjected to small pressures near room temperature. Such materials could form the basis of future refrigeration technologies.<\/h5>\n<p>&nbsp;<\/p>\n<div class=\"article__body serif cleared\">\n<p>Materials known as plastic crystals are composed of molecules that interact through weak long-range forces. As a result, these materials are highly compressible and can be deformed in a reversible manner \u2014 hence the adjective \u2018plastic\u2019. Under certain pressure and temperature conditions, molecules in plastic crystals can start rotating almost freely around their centres of mass. The centres of mass remain localized at well-defined and ordered positions in the crystal lattice, but the rotation leads to orientational disorder. In a paper in\u00a0<i>Nature<\/i>,\u00a0<a href=\"https:\/\/doi.org\/10.1038\/s41586-019-1042-5\" data-track=\"click\" data-label=\"https:\/\/doi.org\/10.1038\/s41586-019-1042-5\" data-track-category=\"body text link\">Li\u00a0<i>et al.<\/i><\/a><sup><a href=\"https:\/\/www.nature.com\/articles\/d41586-019-00974-5?utm_source=feedburner&amp;utm_medium=feed&amp;utm_campaign=Feed%3A+nature%2Frss%2Fcurrent+%28Nature+-+Issue%29#ref-CR1\">1<\/a><\/sup>report that the phase transition between molecular order and disorder in plastic crystals can be used for cooling purposes through the application of small pressures.<\/p>\n<p>&nbsp;<\/p>\n<aside class=\"recommended pull pull--left sans-serif\" data-label=\"Related\"><a href=\"https:\/\/doi.org\/10.1038\/s41586-019-1042-5\" data-track=\"click\" data-track-label=\"recommended article\"><img decoding=\"async\" class=\"recommended__image\" src=\"https:\/\/media.nature.com\/w400\/magazine-assets\/d41586-019-00974-5\/d41586-019-00974-5_16574050.jpg\" \/><\/a><\/p>\n<p class=\"recommended__title serif\">Read the paper: Colossal barocaloric effects in plastic crystals<\/p>\n<\/aside>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>Conventional refrigeration technologies are based on cycles in which greenhouse gases are alternately compressed and expanded. One kilogram of a typical refrigerant gas contributes as much to the greenhouse effect in our planet\u2019s atmosphere as two tonnes of carbon dioxide, which is the equivalent of running a car uninterruptedly for six months (see\u00a0<a href=\"https:\/\/go.nature.com\/2ffbqvt\" data-track=\"click\" data-label=\"https:\/\/go.nature.com\/2ffbqvt\" data-track-category=\"body text link\">go.nature.com\/2ffbqvt<\/a>). In addition, current cooling technologies cannot be scaled down to the dimensions of microchips, which hinders the development of faster and more-compact computers and portable electronic devices. There is therefore a pressing need to find eco-friendly and highly scalable cooling methods for improving many crucial technologies, as well as for protecting the environment.<\/p>\n<p>Solid-state cooling is an environmentally friendly, energy-efficient and highly scalable technology that could solve most of the problems associated with current refrigeration methods. It relies on applying cycles of external magnetic, electric or mechanical fields to compounds called caloric materials. These compounds undergo temperature variations as a result of field-induced phase transitions that involve large changes in entropy \u2014 a measure of disorder.<\/p>\n<p>Examples of caloric materials include ferroelectrics<sup><a href=\"https:\/\/www.nature.com\/articles\/d41586-019-00974-5?utm_source=feedburner&amp;utm_medium=feed&amp;utm_campaign=Feed%3A+nature%2Frss%2Fcurrent+%28Nature+-+Issue%29#ref-CR2\">2<\/a><\/sup>, organic\u2013inorganic hybrid perovskites<sup><a href=\"https:\/\/www.nature.com\/articles\/d41586-019-00974-5?utm_source=feedburner&amp;utm_medium=feed&amp;utm_campaign=Feed%3A+nature%2Frss%2Fcurrent+%28Nature+-+Issue%29#ref-CR3\">3<\/a><\/sup>\u00a0and fast-ion conductors<sup><a href=\"https:\/\/www.nature.com\/articles\/d41586-019-00974-5?utm_source=feedburner&amp;utm_medium=feed&amp;utm_campaign=Feed%3A+nature%2Frss%2Fcurrent+%28Nature+-+Issue%29#ref-CR4\">4<\/a><\/sup>. However, most known caloric materials are not ideal. Some have only modest refrigeration performances, for example, or operate at temperatures different from ambient conditions. And for others, durability and cycling rate can be affected by material fatigue and phase-transition hysteresis \u2014 in which the conditions required for completing a phase transition depend on the direction of the transition. Consequently, progress in solid-state cooling has been limited.<\/p>\n<p>Li and colleagues\u2019 work offers exciting prospects for the field of solid-state cooling. The researchers discovered extremely large entropy changes associated with the molecular order\u2013disorder phase transitions that occur in plastic crystals (Fig. 1a). Moreover, they found that these transitions could be triggered near room temperature by applying small pressures (about 10\u2013100 megapascals), and so could be used for refrigeration purposes (Fig. 1b).<\/p>\n<p>&nbsp;<\/p>\n<figure class=\"figure\">\n<div class=\"embed intensity--high\">\n<div class=\"embed intensity--high\"><img decoding=\"async\" class=\"figure__image\" src=\"https:\/\/media.nature.com\/w800\/magazine-assets\/d41586-019-00974-5\/d41586-019-00974-5_16573296.jpg\" alt=\"\" data-src=\"\/\/media.nature.com\/w800\/magazine-assets\/d41586-019-00974-5\/d41586-019-00974-5_16573296.jpg\" \/><\/div>\n<\/div><figcaption>\n<p class=\"figure__caption sans-serif\"><span class=\"mr10\"><b>Figure 1 | Phases and potential cooling application of plastic crystals.<\/b>\u2002<b>a<\/b>, In materials known as plastic crystals, the orientations of the molecules can be either ordered or disordered.\u00a0<b>b<\/b>, Li\u00a0<i>et al.<\/i><sup><a href=\"https:\/\/www.nature.com\/articles\/d41586-019-00974-5?utm_source=feedburner&amp;utm_medium=feed&amp;utm_campaign=Feed%3A+nature%2Frss%2Fcurrent+%28Nature+-+Issue%29#ref-CR1\">1<\/a><\/sup>\u00a0demonstrate that these materials could be used for refrigeration. In this simple, four-step refrigeration cycle, a plastic crystal is initially in the disordered phase at a temperature\u00a0<i>T<\/i><sub>1<\/sub>. First, pressure is applied to the crystal, which causes the ordered phase to be stabilized and the crystal\u2019s temperature to increase to a value\u00a0<i>T<\/i><sub>2<\/sub>. Second, a heat sink absorbs heat from the crystal and the crystal\u2019s temperature returns to its initial value. Third, pressure is removed from the crystal such that the disordered phase is recovered and the crystal\u2019s temperature decreases to a value\u00a0<i>T<\/i><sub>3<\/sub>. Fourth, the crystal absorbs heat from a heat source and returns to its initial temperature, thereby cooling the heat source.<\/span><\/p>\n<\/figcaption><\/figure>\n<p>The typical field-induced entropy changes measured in archetypal caloric materials are of the order of 10 joules per kilogram per kelvin. By comparison, those found by Li\u00a0<i>et al.<\/i>\u00a0in plastic crystals are of the order of 100\u2009J\u2009kg<sup>\u22121<\/sup>\u2009K<sup>\u22121<\/sup>. For instance, the entropy change reported for the representative plastic crystal neopentylglycol near room temperature is about 390\u2009J\u2009kg<sup>\u22121<\/sup>\u2009K<sup>\u22121<\/sup>, which leads to a large temperature change (roughly 50\u2009K).<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>The molecular mechanisms that underlie the colossal pressure-induced entropy changes in plastic crystals can be understood intuitively. When pressure is applied to the disordered (high-entropy) phase, the molecular rotations are geometrically frustrated; that is, competing interactions between the molecules limit their possible orientations. As a result, the ordered (low-entropy) phase is stabilized. The accompanying reduction in entropy is huge \u2014 similar in magnitude to the entropies typically associated with the melting of a crystal. Conversely, when pressure is removed, the molecules resume their rotations and the disordered phase is re-established, causing an equally large increase in entropy.<\/p>\n<p>Previous studies have already reported giant temperature changes associated with pressure-driven order\u2013disorder phase transitions in caloric materials. For example, in fast-ion conductors, such effects accompany the transition from a normal phase to a superionic phase, in which the conductivity of ions is extremely high<sup><a href=\"https:\/\/www.nature.com\/articles\/d41586-019-00974-5?utm_source=feedburner&amp;utm_medium=feed&amp;utm_campaign=Feed%3A+nature%2Frss%2Fcurrent+%28Nature+-+Issue%29#ref-CR5\">5<\/a><\/sup><sup>\u2013<\/sup><sup><a href=\"https:\/\/www.nature.com\/articles\/d41586-019-00974-5?utm_source=feedburner&amp;utm_medium=feed&amp;utm_campaign=Feed%3A+nature%2Frss%2Fcurrent+%28Nature+-+Issue%29#ref-CR7\">7<\/a><\/sup>. However, plastic crystals are quite different from other caloric materials, and not just because of their huge entropy changes near room temperature: they are cheap and easy to produce, lightweight, non-toxic and flexible. They therefore seem to be especially well suited for the integration of solid-state cooling in electronic devices and mobile applications.<\/p>\n<p>Nevertheless, plastic crystals are not perfect caloric materials. For instance, given their organic nature, they have relatively low melting points (typically about 300\u2013400\u2009K)<sup><a href=\"https:\/\/www.nature.com\/articles\/d41586-019-00974-5?utm_source=feedburner&amp;utm_medium=feed&amp;utm_campaign=Feed%3A+nature%2Frss%2Fcurrent+%28Nature+-+Issue%29#ref-CR8\">8<\/a><\/sup>, which is not desirable for refrigeration applications. In addition, the properties that make plastic crystals highly deformable mean that these materials lack the mechanical resilience to endure many refrigeration cycles. Perhaps most importantly, hysteresis and phase-coexistence effects are likely to weaken the cooling performance of plastic crystals. These technical issues will need to be analysed, and solutions found, if we are to pursue the use of plastic crystals in commercial refrigeration.<\/p>\n<p>Li and colleagues propose combining external pressure and electric fields as a way of avoiding the hysteresis problems associated with plastic crystals. A similar strategy has been demonstrated to work well for compounds called magnetocaloric materials, in which mechanical and magnetic fields have been combined to remove unwanted hysteresis effects<sup><a href=\"https:\/\/www.nature.com\/articles\/d41586-019-00974-5?utm_source=feedburner&amp;utm_medium=feed&amp;utm_campaign=Feed%3A+nature%2Frss%2Fcurrent+%28Nature+-+Issue%29#ref-CR9\">9<\/a><\/sup>.<\/p>\n<p>However, the fact that most molecules in plastic crystals are polar does not guarantee that applying electric fields to these materials will eliminate the effects of hysteresis. The reason is that incredibly large electric fields (about 1,000 kilovolts per centimetre) might be needed to induce any effect on the molecular rotations, as has been shown theoretically for organic\u2013inorganic hybrid perovskites<sup><a href=\"https:\/\/www.nature.com\/articles\/d41586-019-00974-5?utm_source=feedburner&amp;utm_medium=feed&amp;utm_campaign=Feed%3A+nature%2Frss%2Fcurrent+%28Nature+-+Issue%29#ref-CR10\">10<\/a><\/sup>. A possible solution to this problem might be to find or engineer ferroelectric plastic crystals, in which the ordered phase already exhibits collective polar order<sup><a href=\"https:\/\/www.nature.com\/articles\/d41586-019-00974-5?utm_source=feedburner&amp;utm_medium=feed&amp;utm_campaign=Feed%3A+nature%2Frss%2Fcurrent+%28Nature+-+Issue%29#ref-CR11\">11<\/a><\/sup>. Despite these challenges, Li and colleagues\u2019 work represents a step towards finding other caloric materials that have advantageous properties.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<\/div>\n<p><span class=\"emphasis\">Nature<\/span>\u00a0<strong>567<\/strong>, 470-471 (2019)<\/p>\n<p>&nbsp;<\/p>\n<div class=\"emphasis\">doi: 10.1038\/d41586-019-00974-5<\/div>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>(\uc6d0\ubb38: <a href=\"https:\/\/www.nature.com\/articles\/d41586-019-00974-5?utm_source=feedburner&amp;utm_medium=feed&amp;utm_campaign=Feed%3A+nature%2Frss%2Fcurrent+%28Nature+-+Issue%29\">\uc5ec\uae30<\/a>\ub97c \ud074\ub9ad\ud558\uc138\uc694~)<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>&nbsp; &nbsp; Materials called plastic crystals have been found to undergo huge temperature changes when subjected to small pressures near room temperature. Such materials could<a href=\"https:\/\/biochemistry.khu.ac.kr\/lab\/?p=2983\" class=\"more-link\">(more&#8230;)<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[34,36,29,30],"tags":[],"class_list":["post-2983","post","type-post","status-publish","format-standard","hentry","category-lets-do-chemistry","category-lets-do-physics","category-lets-do-science","category-recent-science-news"],"aioseo_notices":[],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack-related-posts":[{"id":951,"url":"https:\/\/biochemistry.khu.ac.kr\/lab\/?p=951","url_meta":{"origin":2983,"position":0},"title":"To make plastic, just add blood","author":"biochemistry","date":"June 25, 2018","format":false,"excerpt":"\u00a0 \u00a0 (\uc6d0\ubb38) \u00a0 \u00a0 \u00a0 Red blood cells contain the iron-based molecule haemoglobin, which has now been harnessed to synthesize plastic. Credit: David Gregory & Debbie Marshall\/CC BY 4.0 To make plastic, just add blood Red blood cells harbour key ingredients for polymerization. \u00a0 \u00a0 Red blood cells normally\u2026","rel":"","context":"In &quot;Let's Do Biology!&quot;","block_context":{"text":"Let's Do Biology!","link":"https:\/\/biochemistry.khu.ac.kr\/lab\/?cat=33"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":3805,"url":"https:\/\/biochemistry.khu.ac.kr\/lab\/?p=3805","url_meta":{"origin":2983,"position":1},"title":"The changing phase of data storage","author":"biochemistry","date":"June 19, 2019","format":false,"excerpt":"\u00a0 \u00a0 The combination of ferroelectrics and phase-change materials provides a route towards phase-change data storage at room temperature, without heating. \u00a0 \u00a0 The current pace of data creation is truly staggering; in 2018 alone, it amounted to 33 zettabytes1. The relentless growth of data generation is likely to continue\u2026","rel":"","context":"In &quot;Let's Do Chemistry!&quot;","block_context":{"text":"Let's Do Chemistry!","link":"https:\/\/biochemistry.khu.ac.kr\/lab\/?cat=34"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":3304,"url":"https:\/\/biochemistry.khu.ac.kr\/lab\/?p=3304","url_meta":{"origin":2983,"position":2},"title":"Structure and functional reselection of the Mango-III fluorogenic RNA aptamer","author":"biochemistry","date":"April 16, 2019","format":false,"excerpt":"\u00a0 \u00a0 Abstract \u00a0 Several turn-on RNA aptamers that activate small-molecule fluorophores have been selected in vitro. Among these, the ~30 nucleotide Mango-III is notable because it binds the thiazole orange derivative TO1-Biotin with high affinity and fluoresces brightly (quantum yield 0.55). Uniquely among related aptamers, Mango-III exhibits biphasic thermal\u2026","rel":"","context":"In &quot;Let's Do Chemistry!&quot;","block_context":{"text":"Let's Do Chemistry!","link":"https:\/\/biochemistry.khu.ac.kr\/lab\/?cat=34"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":2613,"url":"https:\/\/biochemistry.khu.ac.kr\/lab\/?p=2613","url_meta":{"origin":2983,"position":3},"title":"Forget everything you know about 3D printing \u2014 the \u2018replicator\u2019 is here","author":"biochemistry","date":"February 1, 2019","format":false,"excerpt":"\u00a0 \u00a0 Rather than building objects layer by layer, the printer creates whole structures by projecting light into a resin that solidifies. \u00a0 \u00a0 \u00a0 They nicknamed it \u2018the replicator\u2019 \u2014 in homage to the machines in the\u00a0Star Trek\u00a0saga that can materialize virtually any inanimate object. Researchers have unveiled a\u00a03D\u2026","rel":"","context":"In &quot;Let's Do Chemistry!&quot;","block_context":{"text":"Let's Do Chemistry!","link":"https:\/\/biochemistry.khu.ac.kr\/lab\/?cat=34"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":3415,"url":"https:\/\/biochemistry.khu.ac.kr\/lab\/?p=3415","url_meta":{"origin":2983,"position":4},"title":"Plastics are forever","author":"biochemistry","date":"April 25, 2019","format":false,"excerpt":"\u00a0 \u00a0 Bruce C. Gibb explains why plastic isn\u2019t always fantastic. \u00a0 \u00a0 Plastics are marvellous. There is no getting away from them. Through their intrinsic properties, plastic materials have found ubiquitous application in building and construction, electronics, automotive design, a myriad of health applications, packaging, paints and coatings, adhesives\u2026","rel":"","context":"In &quot;Essays on Science&quot;","block_context":{"text":"Essays on Science","link":"https:\/\/biochemistry.khu.ac.kr\/lab\/?cat=32"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":4883,"url":"https:\/\/biochemistry.khu.ac.kr\/lab\/?p=4883","url_meta":{"origin":2983,"position":5},"title":"Heat transferred in a previously unknown way","author":"biochemistry","date":"December 14, 2019","format":false,"excerpt":"\u00a0 \u00a0 Experiments show that quantum fluctuations can allow heat to be transported between two objects separated by a vacuum gap. This effect could be harnessed to exploit and control heat transfer in nanoscale devices. \u00a0 \u00a0 Acoustic waves and electromagnetic waves can transport heat between objects through their respective\u2026","rel":"","context":"In &quot;'06. \uc5d0\ub108\uc9c0\uc640 \uc5d4\ud2b8\ub85c\ud53c'\uc640 '07. \uacfc\ud559\uacfc \ubb38\uba85' \uad00\ub828&quot;","block_context":{"text":"'06. \uc5d0\ub108\uc9c0\uc640 \uc5d4\ud2b8\ub85c\ud53c'\uc640 '07. \uacfc\ud559\uacfc \ubb38\uba85' \uad00\ub828","link":"https:\/\/biochemistry.khu.ac.kr\/lab\/?cat=42"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]}],"jetpack_sharing_enabled":false,"jetpack_shortlink":"https:\/\/wp.me\/p9Xo1j-M7","_links":{"self":[{"href":"https:\/\/biochemistry.khu.ac.kr\/lab\/index.php?rest_route=\/wp\/v2\/posts\/2983","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/biochemistry.khu.ac.kr\/lab\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/biochemistry.khu.ac.kr\/lab\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/biochemistry.khu.ac.kr\/lab\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/biochemistry.khu.ac.kr\/lab\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2983"}],"version-history":[{"count":1,"href":"https:\/\/biochemistry.khu.ac.kr\/lab\/index.php?rest_route=\/wp\/v2\/posts\/2983\/revisions"}],"predecessor-version":[{"id":2984,"href":"https:\/\/biochemistry.khu.ac.kr\/lab\/index.php?rest_route=\/wp\/v2\/posts\/2983\/revisions\/2984"}],"wp:attachment":[{"href":"https:\/\/biochemistry.khu.ac.kr\/lab\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2983"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/biochemistry.khu.ac.kr\/lab\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2983"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/biochemistry.khu.ac.kr\/lab\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2983"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}