Shape-stabilized phase change materials (ss-PCMs) offer excellent thermal energy storage/release capabilities through phase transition without deformation of the part shape. However, the development of ss-PCMs faces limitations from both material availability and processing techniques. Most of the ss-PCMs are stiff materials with compromised mechanical properties. Additive manufacturing (AM) outstands conventional manufacturing by enabling fabrication of complex geometries with improved heat transfer and energy efficiency. Here, we present a vat photopolymerization (VP) AM of a rubber-based ss-PCMs. In this process an acrylic scaffold is photo-crosslinked around suspended latex particles, which subsequently coalesce and form a semi-interpenetrating network via a thermal post process. Through this approach, we demonstrate successful fabrication of intricate geometries of ss-PCMs based on styrene-isoprene-styrene block copolymers encapsulating polyethylene glycol (SIS-ss-PCM). The SIS-ss-PCMs exhibit high latent heat of 8.4 to 38.14 J/g. Furthermore, the SIS-ss-PCMs demonstrate excellent mechanical properties as elastomer with elongation of 251% to 716% and tensile strength of 1.23 to 3.16 MPa. Corresponding simulations showed that SIS-ss-PCM provides cooling effects and provide a uniform temperature distribution comparable to commercially available phase change material. This VP-printable elastomeric ss-PCM technology not only holds promise for efficient thermal management in electronics but also offers protection as a shock absorber

Schematic of the fabrication of elastomeric ss-PCM through vat photopolymerization.

Thermal performance (left) and tensile properties (right) of SIS-ss-PCMs with differnt polyethylene glycol (PEG) contents.

Timothy Long

Arizona State University

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