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Comparison of the enthalpic relaxation of poly(lactide– co ‐glycolide) 50:50 nanospheres and raw polymer
Author(s) -
Bailey N. A.,
Sandor M.,
Kreitz M.,
Mathiowitz E.
Publication year - 2002
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.11109
Subject(s) - glass transition , relaxation (psychology) , polymer , materials science , polymer chemistry , raw material , chemical engineering , kinetics , lactide , thermodynamics , chemistry , composite material , polymerization , organic chemistry , psychology , social psychology , physics , quantum mechanics , engineering
The phenomenon of enthalpic relaxation was evaluated for poly(lactide‐ co ‐glycolide) (PLGA, 50:50), in terms of storage of nanospheres for use as a controlled drug delivery system. Samples were stored for different times and temperatures below the glass transition temperature ( T g ). Relaxation occurred at a significant rate up to 15 degrees below the T g of 39.2°C. The effect of polymer morphology was considered by comparing the relaxation kinetics of the raw polymer with that of nanospheres formed using a novel technique. The nanospheres were shown to have a larger change in heat capacity at the glass transition and a longer average relaxation time than that of the raw polymer, and the relationship between these two parameters was discussed. For both the raw polymer and the nanospheres, relaxation was found to occur at a significant rate at room temperature. The storage of this system at subambient temperatures was therefore deemed important for maintaining the physicochemical properties of the system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1868–1872, 2002