{"title":"有机玻璃形成液体和易碎性的概念","authors":"Christiane Alba-Simionesco","doi":"10.5802/crphys.148","DOIUrl":null,"url":null,"abstract":"An important category of glass-forming materials is organic; it includes molecular liquids, polymers, solutions, proteins that can be vitrified by cooling the liquid under standard conditions or after special thermal treatments. The range of applications is large from materials to life sciences and recently to electronics. To distinguish them from other systems described in this issue, some specific properties such as the range of their glass transition temperature (T g ), their ability to vitrify and some rules of thumb to locate T g are presented. The most remarkable property of these liquids is how fast in temperature their viscosity or structural relaxation time increases as approaching T g . To characterize this behavior and rank the liquids of different strength, C.A. Angell introduced the concept of Fragility nearly 40 years ago. He proposed to classify liquids as fragile or strong in an Arrhenius plot with T g scaling (the strongest ones have never being observed in organic glasses, except for water under specific conditions). The T g value and the fragility index of a given liquid can be changed by applying pressure, i.e. changing the density. One can then explore the properties of the supercooled/overcompressed liquid and the glass in a P-T phase diagram. The T g line corresponds to an isochronic line, i.e. a line at constant relaxation time for different pairs of density-temperature. We observe that all data can be placed on master-curves that depend only on a single density- and species-dependent and T-independent effective interaction energy, E ∞ (ρ). An isochoric fragility index is defined as an intrinsic property of a given liquid, that can help in rationalizing all the correlations between the glass properties below T g and the viscous slowing down just above T g from which they are made. Geometrical confinement of liquids is also a way to modify the dynamics of a liquid and the properties of a glass; it corresponds to a large number of situations encountered in nature. Another phase diagram T-d (d defining pore size) can be defined with a non-trivial pore size dependence of the glass transition, which is also strongly affected by surface interactions.","PeriodicalId":50650,"journal":{"name":"Comptes Rendus Physique","volume":"82 1","pages":"0"},"PeriodicalIF":1.3000,"publicationDate":"2023-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Organic Glass-Forming Liquids and the Concept of Fragility\",\"authors\":\"Christiane Alba-Simionesco\",\"doi\":\"10.5802/crphys.148\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"An important category of glass-forming materials is organic; it includes molecular liquids, polymers, solutions, proteins that can be vitrified by cooling the liquid under standard conditions or after special thermal treatments. The range of applications is large from materials to life sciences and recently to electronics. To distinguish them from other systems described in this issue, some specific properties such as the range of their glass transition temperature (T g ), their ability to vitrify and some rules of thumb to locate T g are presented. The most remarkable property of these liquids is how fast in temperature their viscosity or structural relaxation time increases as approaching T g . To characterize this behavior and rank the liquids of different strength, C.A. Angell introduced the concept of Fragility nearly 40 years ago. He proposed to classify liquids as fragile or strong in an Arrhenius plot with T g scaling (the strongest ones have never being observed in organic glasses, except for water under specific conditions). The T g value and the fragility index of a given liquid can be changed by applying pressure, i.e. changing the density. One can then explore the properties of the supercooled/overcompressed liquid and the glass in a P-T phase diagram. The T g line corresponds to an isochronic line, i.e. a line at constant relaxation time for different pairs of density-temperature. We observe that all data can be placed on master-curves that depend only on a single density- and species-dependent and T-independent effective interaction energy, E ∞ (ρ). An isochoric fragility index is defined as an intrinsic property of a given liquid, that can help in rationalizing all the correlations between the glass properties below T g and the viscous slowing down just above T g from which they are made. Geometrical confinement of liquids is also a way to modify the dynamics of a liquid and the properties of a glass; it corresponds to a large number of situations encountered in nature. Another phase diagram T-d (d defining pore size) can be defined with a non-trivial pore size dependence of the glass transition, which is also strongly affected by surface interactions.\",\"PeriodicalId\":50650,\"journal\":{\"name\":\"Comptes Rendus Physique\",\"volume\":\"82 1\",\"pages\":\"0\"},\"PeriodicalIF\":1.3000,\"publicationDate\":\"2023-08-03\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Comptes Rendus Physique\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.5802/crphys.148\",\"RegionNum\":4,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"ASTRONOMY & ASTROPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Comptes Rendus Physique","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.5802/crphys.148","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
Organic Glass-Forming Liquids and the Concept of Fragility
An important category of glass-forming materials is organic; it includes molecular liquids, polymers, solutions, proteins that can be vitrified by cooling the liquid under standard conditions or after special thermal treatments. The range of applications is large from materials to life sciences and recently to electronics. To distinguish them from other systems described in this issue, some specific properties such as the range of their glass transition temperature (T g ), their ability to vitrify and some rules of thumb to locate T g are presented. The most remarkable property of these liquids is how fast in temperature their viscosity or structural relaxation time increases as approaching T g . To characterize this behavior and rank the liquids of different strength, C.A. Angell introduced the concept of Fragility nearly 40 years ago. He proposed to classify liquids as fragile or strong in an Arrhenius plot with T g scaling (the strongest ones have never being observed in organic glasses, except for water under specific conditions). The T g value and the fragility index of a given liquid can be changed by applying pressure, i.e. changing the density. One can then explore the properties of the supercooled/overcompressed liquid and the glass in a P-T phase diagram. The T g line corresponds to an isochronic line, i.e. a line at constant relaxation time for different pairs of density-temperature. We observe that all data can be placed on master-curves that depend only on a single density- and species-dependent and T-independent effective interaction energy, E ∞ (ρ). An isochoric fragility index is defined as an intrinsic property of a given liquid, that can help in rationalizing all the correlations between the glass properties below T g and the viscous slowing down just above T g from which they are made. Geometrical confinement of liquids is also a way to modify the dynamics of a liquid and the properties of a glass; it corresponds to a large number of situations encountered in nature. Another phase diagram T-d (d defining pore size) can be defined with a non-trivial pore size dependence of the glass transition, which is also strongly affected by surface interactions.
期刊介绍:
The Comptes Rendus - Physique are an open acess and peer-reviewed electronic scientific journal publishing original research article. It is one of seven journals published by the Académie des sciences.
Its objective is to enable researchers to quickly share their work with the international scientific community.
The Comptes Rendus - Physique also publish journal articles, thematic issues and articles on the history of the Académie des sciences and its current scientific activity.
From 2020 onwards, the journal''s policy is based on a diamond open access model: no fees are charged to authors to publish or to readers to access articles. Thus, articles are accessible immediately, free of charge and permanently after publication.
The Comptes Rendus - Physique (8 issues per year) cover all fields of physics and astrophysics and propose dossiers. Thanks to this formula, readers of physics and astrophysics will find, in each issue, the presentation of a subject in particularly rapid development. The authors are chosen from among the most active researchers in the field and each file is coordinated by a guest editor, ensuring that the most recent and significant results are taken into account. In order to preserve the historical purpose of the Comptes Rendus, these issues also leave room for the usual notes and clarifications. The articles are written mainly in English.