Abstract
Polylactide (PLA) crystallizes to form extended-chain crystals in a Langmuir monolayer because crystallization is accelerated on the water surface. This is a unique situation where chain packing can be analyzed by simply measuring the lamellar thickness. Herein, star-shaped poly(l-lactide)s (PLLAs) with 2–12 arms were synthesized through the polymerization of l-lactide with various polyols as initiators, and their crystallization behavior in a monolayer was studied via atomic force microscopy. The PLLAs comprising 2–4 arms crystallized with all arms aligned in the same direction and being folded at the central polyol unit. Meanwhile, the PLLAs comprising 6 and 12 arms crystallized with both halves of the arms extended from the center to the opposite directions, most likely due to the steric hindrance of the crowded arms. Considering that the PLLAs crystallized from a once-formed condensed amorphous state during compression, they have a strong tendency to crystallize with the arms aligned in the same direction. The crystallization rate of star-shaped PLAs is known to reduce compared with that of a linear PLA even if the number of arms is as few as 2. This should be closely related to the unique crystallization behavior of the star-shaped PLLAs with the arms aligned in the same direction.
Original language | English |
---|---|
Pages (from-to) | 5486–5494 |
Number of pages | 9 |
Journal | Langmuir |
Volume | 39 |
Issue number | 15 |
Early online date | 7 Apr 2023 |
DOIs | |
Publication status | Published - 18 Apr 2023 |
Bibliographical note
Acknowledgments:J.K. appreciates the financial support by JSPS KAKENHI Grant Numbers JP15H03861, JP17K19147, JP18H02025, JP20H05201, JP21H01993, and JP21K18993. K.F. and T.K. appreciate the financial support by JSPS KAKENHI grant numbers JP19H05716 and JP19H05715, respectively. J.K. also appreciates the financial support by the Ogasawara Foundation for the Promotion of Science and Engineering.