Topologically controlled phase transitions and nanoscale film self-assemblies of cage poly(-caprolactone) and its counterparts

• Published in: Polymer chemistry 2021-02, Vol.12 (5), p.744-758
• Main Authors: Ree, Brian J, Mato, Yoshinobu, Xiang, Li, Kim, Jehan, Isono, Takuya, Satoh, Toshifumi
• Format: Article
• Language: English
• Subjects: Cages; Crystal lattices; Crystal structure; Crystallinity; Crystallization; Data analysis; Grazing incidence; Heat of fusion; Lamellar structure; Mathematical morphology; Melt temperature; Melting; Orthorhombic lattice; Phase transitions; Polymer chemistry; Synchrotrons; Thermal stability; Thickness; Topology; X-ray scattering
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/d0py01567a

Here we report the first quantitative investigation of nanoscale film morphologies of a cage-shaped poly( -caprolactone) ( cg -PCL 9k ) and its counterparts in star, cyclic, and linear topologies ( st -PCL 9k , cy -PCL 6k , and l -PCL 6k ) with consideration of topological influence through synchrotron grazing incidence X-ray scattering analysis. The folded crystalline layer thickness l c is found to be in the increasing order of: st -PCL 9k < l -PCL 6k < cy -PCL 6k < cg -PCL 9k . Additional structural parameters, such as lamellar orientation, crystallinity, and orientation of orthorhombic lattice in nanoscale film, exhibit intricate dependencies on their molecular topologies and steric influences from the molecular joints and end groups. Nevertheless, all topological PCLs form lamellar structures based on the orthorhombic crystal lattice in nanoscale films. In addition, crystallization temperature T c and crystal melting temperature T m of all PCLs in bulk are highly dependent on the molecular topology; both T c and T m follow the same increasing trend of: st -PCL 9k < l -PCL 6k < cy -PCL 6k < cg -PCL 9k . Phase transition characteristics such as heat of fusion and crystallinity in bulk state, and thermal stability also depend upon the topological and steric influences. Here we report the first quantitative investigation of nanoscale film morphologies of a cage-shaped poly( -caprolactone) and its counterparts in star, cyclic, and linear topologies through synchrotron grazing incidence X-ray scattering analysis.