BEGIN:VCALENDAR VERSION:2.0 PRODID:icalendar-ruby CALSCALE:GREGORIAN X-WR-CALNAME:DMSE Doctoral Thesis Defense - Sungjin Kim X-WR-TIMEZONE:Eastern Time (US & Canada) BEGIN:VEVENT DTSTAMP:20260721T103349Z UID:tag:localist.com\,2008:EventInstance_33362189607365 DTSTART:20200506T180000Z DTEND:20200506T190000Z DESCRIPTION:DMSE Doctoral Thesis Defense \n\n \n\nUtilizing Bioinspired Met al-Coordinate Bonding in the Solidification of Soft gels via Crosslinking\ , Dehydration and Mineralization\n\n \n\nSungjin Kim\n\nWednesday\, May 6\ , 2020 \n\n2:00 – 3:00 PM EDT \n\nContact dmse-gradoffice@mit.edu for gu est link.\n\nIn nature\, most organisms embark on the journey of life in a predominantly soft and compliant state and go through a series of materia l solidification processes to serve a multitude of complex functions at va rious life stages. Many of these material transitions occur via an organic -inorganic processing pathway that involves a genetically programmed hiera rchy of spatiotemporally orchestrated macromolecular crosslinking\, dehydr ation\, and mineralization events. With the growing need for sustainable m aterial processing\, the interest has increased in understanding the under lying physical-chemical mechanisms that control the change in properties d uring such biological material transitions. Hence\, in this thesis\, we ut ilized polymers in combination with metal-coordinating ligands to form var ious types of metal-crosslinked networks as a platform to explore the poss ibly synergistic roles of crosslinking\, dehydration\, and mineralization in building solid materials out of soft gels. First\, we explored how meta l-coordinate crosslinking contributes to macromolecular material mechanics upon dehydration-induced solidification\, using mussel-inspired metal-cat echol or metal-histidine crosslinked polymer hydrogels. We found evidence to suggest that a small amount of locally bound water by metal-coordinate complexes maintains their dynamic nature as mechanically dissipative cross links even in a dehydrated polymer network. In addition\, a scaling relati onship between the timescale of macroscopic network relaxation time and th e amount of bound microscopic water was elucidated by demonstrating contro l over the fractions of dynamic and permanent crosslinks within the networ k. Second\, we investigated the relationship between macromolecular crossl inking and mineralization. Inspired by the self-assembling metal-reinforce d mussel holdfast threads\, we tested if metal-coordinate polymer networks can be utilized as simple composite scaffolds for direct in situ crosslin k mineralization. Starting with aqueous solutions of well-dispersed metal- binding polymers\, we found that inter-molecular metal-ion coordination co mplexes can serve as mineral nucleation sites\, whereby significant mechan ical reinforcement is achieved upon nanoparticle growth localized at the m etal-coordinate network crosslink sites. Finally\, we studied the control over mineralization of biominerals using catecholic metal-binding additive s. We found that a common edible polyphenol\, tannic acid (TA)\, ubiquitou s in natural plants and foods could work as an effective binder for Ca to stabilize amorphous calcium carbonate (ACC). Furthermore\, we demonstrated that the TA-induced ACC can readily transition to hydroxyapatites\, or bo ne mineral\, in simulated body fluid at human body temperature.\n\nThesis Supervisor \n\nNiels Holten-Andersen\, Associate Professor\, Materials Sci ence and Engineering\, Massachusetts Institute of Technology \n\nThesis Co mmittee \n\nJulia Ortony\, Finmeccanica Assistant Professor\, Materials Sc ience and Engineering\, Massachusetts Institute of Technology \n\nKrystyn J. Van Vliet\, Michael (1949) and Sonja Koerner Professor\, Materials Scie nce and Engineering\, Massachusetts Institute of Technology LOCATION: SUMMARY:DMSE Doctoral Thesis Defense - Sungjin Kim URL;VALUE=URI:https://calendar.mit.edu/event/dmse_doctoral_thesis_defense_- _sungjin_kim CATEGORIES:Thesis defense END:VEVENT END:VCALENDAR