Change in Crystal Structure and Polymerization Reactivity for the Solid-State Polymerization of Muconic Esters

• Published in: Crystal growth & design 2007-06, Vol.7 (6), p.1078-1085
• Main Authors: Matsumoto, Akikazu, Furukawa, Daisuke, Mori, Yutaka, Tanaka, Toshihiro, Oka, Kunio
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Organic compounds; Organic polymers; Physicochemistry of polymers; Physics; Properties and characterization; Single-crystal and powder diffraction; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; X-ray diffraction and scattering
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/cg0606444

We report the polymerization mechanism and kinetics of muconic esters as the 1,3-diene monomers during solid-state polymerization via a crystal-to-crystal transformation. We have revealed a change in the structure of the muconate crystals accompanying the shrinking and expanding of the lattice lengths, on the basis of the X-ray single-crystal structure analysis of the monomers and polymers as well as a change in the transient structure monitored by powder X-ray diffraction during the continuous X-ray radiation. The polymerization rate is closely related to the molecular stacking distance in the monomer crystals because the polymer chain skeletons have the same conformational structure in the crystals. A lattice length in the direction along which a polymer chain is produced decreases during the transformation from monomer to polymer crystals when monomer molecules are arranged in a columnar assembly with a stacking distance greater than the fiber period of the resulting polymer, and vice versa. A strain in the crystals is formed by a mismatch between the monomer and polymer crystal lattices accumulated and then finally released during the polymerization.