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Abstract Optoelectronics are crucial for developing energy‐efficient chip technology, with phase‐change materials (PCMs) emerging as promising candidates for reconfigurable components in photonic integrated circuits, such as nonvolatile phase shifters. Antimony sulfide (Sb2S3) stands out due to its low optical loss and considerable phase‐shifting properties, along with the non‐volatility of both phases. This study demonstrates that the crystallization kinetics of Sb2S3can be switched from growth‐driven to nucleation‐driven by altering the sample dimension from bulk to film. This tuning of the crystallization process is critical for optical switching applications requiring control over partial crystallization. Calorimetric measurements with heating rates spanning over six orders of magnitude, reveal that, unlike conventional PCMs that crystallize below the glass transition, Sb2S3exhibits a measurable glass transition prior to crystallization from the undercooled liquid (UCL) phase. The investigation of isothermal crystallization kinetics provides insights into nucleation rates and crystal growth velocities while confirming the shift to nucleation‐driven behavior at reduced film thicknesses—an essential aspect for effective device engineering. A fundamental difference in chemical bonding mechanisms was identified between Sb2S3, which exhibits covalent bonding in both material phases, and other PCMs, such as GeTe and Ge2Sb2Te5, which demonstrate pronounced bonding alterations upon crystallization.
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This content will become publicly available on November 23, 2025
Swelling‐Shrinking Behavior of a Hydrogel with a CO 2 ‐Switchable Volume Phase Transition Temperature
Abstract Macromolecules exhibit rich phase behavior that may be exploited for advanced material design. In particular, the volume phase transition in certain crosslinked hydrogels is a key property controlling the transition between a collapsed/dehydrated and a swollen/hydrated state, thereby regulating the release and absorption of water via a temperature change. In this work, a simple and tunable system exhibiting a carbon dioxide (CO2)‐switchable volume phase transition is introduced, which displays isothermal swelling‐shrinking behavior that is activated by addition and removal of CO2,respectively. Through systematic compositional studies, shifts in phase transition temperatures of up to 8.6 °C are measured upon CO2exposure, which enables pronounced isothermal swelling in response to CO2, reaching up to a fivefold increase in mass. The shift in transition temperature and the extent of swelling are controlled by the hydrogel composition, thus enabling the transition temperature and swelling degree to be tuned a priori for a particular application. Controlled release experiments from these gels upon a CO2‐induced phase transition suggest viability for drug delivery applications. It is anticipated that this work will motivate and expand efforts to exploit phase behavior for smart material development.
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- Award ID(s):
- 2143146
- PAR ID:
- 10556401
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Macromolecular Rapid Communications
- ISSN:
- 1022-1336
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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