Abstract
Complex crystal induced gelation of poly(l-lactic acid) (PLLA) solutions was studied for a series of solvents, including N,N-dimethylformamide (DMF). By cooling the solutions prepared at elevated temperatures, PLLA gels were produced in solvents that induced complex crystals (ε-crystals) with PLLA. Fibrous structure of PLLA in the gel with DMF was observed by polarizing optical microscopy, field emission electron microscopy, and atomic force microscopy. Upon heating, the crystal form of PLLA in the DMF gel changed from ε-crystal to α-crystal, the major crystal form in common untreated PLLA films, but the morphology and high elastic modulus of the gel remained until the α-crystal dissolved at higher temperature. In addition, a solvent exchanging method was developed, which allowed PLLA gels to be prepared in other useful solvents that do not induce ε-crystals without losing the morphology and mechanical properties.
Original language | English |
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Pages (from-to) | 4369-4378 |
Number of pages | 10 |
Journal | Polymer |
Volume | 55 |
Issue number | 16 |
DOIs | |
State | Published - Aug 5 2014 |
Funding
YYW and JWM acknowledge the financial support by the US Department of Energy, Basic Energy Sciences, Division of Materials Sciences and Engineering ( ERKCC02 ). This work is partially supported by a Grant-in Aid for Young Scientists (B) ( 26870245 ) from the Ministry of Education, Culture, Science, Sports and Technology of Japan .
Keywords
- Complex crystal
- Gelation
- Poly(l-lactic acid)