title: Atomic and vibrational origins of mechanical toughness in bioactive cement during setting.
abstract: Bioactive glass ionomer cements (GICs) have been in widespread use for ∼40 years in dentistry and medicine. However, these composites fall short of the toughness needed for permanent implants. Significant impediment to improvement has been the requisite use of conventional destructive mechanical testing, which is necessarily retrospective. Here we show quantitatively, through the novel use of calorimetry, terahertz (THz) spectroscopy and neutron scattering, how GIC's developing fracture toughness during setting is related to interfacial THz dynamics, changing atomic cohesion and fluctuating interfacial configurations. Contrary to convention, we find setting is non-monotonic, characterized by abrupt features not previously detected, including a glass-polymer coupling point, an early setting point, where decreasing toughness unexpectedly recovers, followed by stress-induced weakening of interfaces. Subsequently, toughness declines asymptotically to long-term fracture test values. We expect the insight afforded by these in situ non-destructive techniques will assist in raising understanding of the setting mechanisms and associated dynamics of cementitious materials.
authors.affiliation: Department of Oral Diagnostics, Faculty of Dentistry, Semmelweis University, Budapest 1088, Hungary.
authors.forename: Kun V
authors.initials: KV
authors.lastname: Tian
authors.affiliation: Department of Electronic and Electrical Engineering, University of Chester, Thornton Science Park, Chester CH2 4NU, UK.|School of Electronic Engineering and Computer Science, Queen Mary University of London, London E1 4NS, UK.
authors.forename: Bin
authors.initials: B
authors.lastname: Yang
authors.affiliation: Laboratory of Extreme Glassy State, State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China.|Department of Chemistry and Bioscience, Aalborg University, DK-9220 Aalborg, Denmark.
authors.forename: Yuanzheng
authors.initials: Y
authors.lastname: Yue
authors.affiliation: ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK.
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Bowron
authors.affiliation: ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK.
authors.forename: Jerry
authors.initials: J
authors.lastname: Mayers
authors.affiliation: School of Electronic Engineering and Computer Science, Queen Mary University of London, London E1 4NS, UK.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Donnan
authors.affiliation: Department of Oral Diagnostics, Faculty of Dentistry, Semmelweis University, Budapest 1088, Hungary.
authors.forename: Csaba
authors.initials: C
authors.lastname: Dobó-Nagy
authors.affiliation: School of Sport, Health and Applied Science, St Mary's University, London TW1 4SX, UK.
authors.forename: John W
authors.initials: JW
authors.lastname: Nicholson
authors.affiliation: College of Chemistry, Beijing Normal University, Beijing 100875, China.
authors.forename: De-Cai
authors.initials: DC
authors.lastname: Fang
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK.
authors.forename: A Lindsay
authors.initials: AL
authors.lastname: Greer
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Chass
authors.affiliation: Laboratory of Extreme Glassy State, State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China.|Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK.|Department of Physics, Institute of Mathematics, Physics and Computer Science, Aberystwyth University, Aberystwyth SY23 3BZ, UK.
authors.forename: G Neville
authors.initials: GN
authors.lastname: Greaves
mesh_terms: D002151:Calorimetry; D005899:Glass Ionomer Cements; D008422:Materials Testing; D055595:Mechanical Phenomena; D013314:Stress, Mechanical; D055068:Terahertz Spectroscopy; D014732:Vibration
chemical_list: D005899:Glass Ionomer Cements