Single-component optically transparent film of a star-shaped cage silsesquioxane derivative and its phase change behavior

• Published in: Polymer journal 2022-10, Vol.54 (10), p.1179-1190
• Main Authors: Suzuki, Rina, Li, Lina, Imoto, Hiroaki, Takagi, Hideaki, Sakurai, Shinichi, Naka, Kensuke
• Format: Article
• Language: English
• Subjects: 639/638/455/960; 639/925/357; Biomaterials; Bioorganic Chemistry; Cages; Chemical synthesis; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Crystal structure; Crystallinity; Crystals; Macromolecules; Melt temperature; Melting; Molecular clusters; Original Article; Phase transitions; Polyhedral oligomeric silsesquioxane; Polymer Sciences; Recrystallization; Room temperature; Substitutes; Surfaces and Interfaces; Thin Films; X-ray scattering
• ISSN: 0032-3896; 1349-0540
• DOI: 10.1038/s41428-022-00674-4

Modularly synthesized giant molecular clusters containing rigid spherical molecules as element-blocks are a new class of unconventional macromolecules. Among various candidates for rigid spherical molecules, cage octasilsesquioxane (T 8 ) frameworks have been demonstrated to be an efficient building block for designing well-defined 3D solid materials due to the flexible designability of their organic substituents. Here, we studied the crystalline phase and phase transition behavior of an optically transparent film of star-shaped (heptaisobutyl-T 8 -silsesquioxy)propyl-substituted octadimethylsiloxy-Q 8 -silsesquioxane ( star-POSS ) by DSC and wide-angle X-ray scattering (WAXS) measurements. This star-POSS exhibited a crystalline phase with a hexagonal system at room temperature and underwent melting above the melting temperature ( T m ). Furthermore, the specimens underwent recrystallization even at temperature above T m , resulting in the same hexagonal system with slightly larger a - and c -axis lengths. The amorphous state of the surrounding isobutyl substituents on the T 8 -cage framework provides an optically transparent film of star-POSS . The crystalline phase and phase transition behavior of an optically transparent film of star-shaped (heptaisobutyl-T 8 -silsesquioxy)propyl-substituted octadimethylsiloxy-Q 8 -silsesquioxane ( star-POSS ) were studied by DSC and WAXS measurements. This star-POSS exhibited a crystalline phase with a hexagonal system at room temperature and underwent melting above the melting temperature ( T m ). The specimens underwent recrystallization even at temperature above T m , resulting in the same hexagonal system with slightly larger a - and c -axis lengths. The amorphous state of the surrounding isobutyl substituents on the T 8 -cage framework provides an optically transparent film.