Title

Thermally-Activated Phase Transitions in Seven Spiro-Based Crystals

Presenter Information

Olivia AdkinsFollow

Academic Level at Time of Presentation

Freshmen

Major

Chemistry

Minor

Biology

List all Project Mentors & Advisor(s)

Sebastian Jezowski, PhD

Presentation Format

Poster Presentation

Abstract/Description

Mechanical activation of chemical bonds targets early detection of failure and fatigue in polymers. Self-healing functional polymers based on spiropyrans (SP) have already been built. Their mechanism of action is based on the C-to-O bond (spiro bond) being selectively cleaved upon mechanical activation. The cleavage of a covalent bond and thus the failure of the spiro-based material is signaled by a sharp change in color from colorless to purple. This change also occurs upon heating (thermochromism) or illumination with light (photochromism). Since mechanical action as well as heating and illumination are capable of causing the spiro-bond to snap, it is necessary to establish detailed information on the thermal properties of these spiro-based molecules. We have applied Differential Scanning Calorimetry method to establish the thermal properties of seven SP-based crystalline materials. While some of them follow the well-established melting-freezing pattern normally seen for many crystalline substances, some show complex array of peaks with enthalpies that can only be assigned to polymorphic phase transitions within a crystal.

Spring Scholars Week 2019 Event

Sigma Xi Poster Competition (Juried)

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Thermally-Activated Phase Transitions in Seven Spiro-Based Crystals

Mechanical activation of chemical bonds targets early detection of failure and fatigue in polymers. Self-healing functional polymers based on spiropyrans (SP) have already been built. Their mechanism of action is based on the C-to-O bond (spiro bond) being selectively cleaved upon mechanical activation. The cleavage of a covalent bond and thus the failure of the spiro-based material is signaled by a sharp change in color from colorless to purple. This change also occurs upon heating (thermochromism) or illumination with light (photochromism). Since mechanical action as well as heating and illumination are capable of causing the spiro-bond to snap, it is necessary to establish detailed information on the thermal properties of these spiro-based molecules. We have applied Differential Scanning Calorimetry method to establish the thermal properties of seven SP-based crystalline materials. While some of them follow the well-established melting-freezing pattern normally seen for many crystalline substances, some show complex array of peaks with enthalpies that can only be assigned to polymorphic phase transitions within a crystal.