TY - JOUR
T1 - Polystyrene freeze-dried from dilute solution
T2 - Tg depression and residual solvent effects
AU - Zheng, W.
AU - Simon, S. L.
N1 - Funding Information:
The authors gratefully acknowledge funding from the National Science Foundation for support of this work through NIRT grant NSF DMR- 0304640. Useful discussions with Prof D.J. Plazek and Prof G.B. McKenna are also acknowledged.
PY - 2006/5/3
Y1 - 2006/5/3
N2 - The calorimetric glass transition temperature, Tg, was measured for both linear and cyclic polystyrenes freeze-dried from dilute solutions of 0.10, 0.05, and 0.02% of polymer by weight in benzene. Upon freeze-drying, Tg was found to be depressed by 4-15 K depending on the sample, solvent concentration, and freezing conditions. Annealing under vacuum at moderate temperatures, from 40 to 140 °C and 0.05 Torr, resulted in the shift of Tg back towards its bulk value and was accompanied by a decrease in sample weight. The data is consistent with the observed weight loss being due to residual solvent. The amount of residual solvent is a strong function of the annealing temperature and the initial freeze-drying solution concentration; exposure to vacuum at temperatures far below Tg is generally insufficient for residual solvent removal.
AB - The calorimetric glass transition temperature, Tg, was measured for both linear and cyclic polystyrenes freeze-dried from dilute solutions of 0.10, 0.05, and 0.02% of polymer by weight in benzene. Upon freeze-drying, Tg was found to be depressed by 4-15 K depending on the sample, solvent concentration, and freezing conditions. Annealing under vacuum at moderate temperatures, from 40 to 140 °C and 0.05 Torr, resulted in the shift of Tg back towards its bulk value and was accompanied by a decrease in sample weight. The data is consistent with the observed weight loss being due to residual solvent. The amount of residual solvent is a strong function of the annealing temperature and the initial freeze-drying solution concentration; exposure to vacuum at temperatures far below Tg is generally insufficient for residual solvent removal.
KW - Freeze-drying
KW - Glass transition temperature
KW - Polystyrene
UR - http://www.scopus.com/inward/record.url?scp=33646153766&partnerID=8YFLogxK
U2 - 10.1016/j.polymer.2006.03.035
DO - 10.1016/j.polymer.2006.03.035
M3 - Article
AN - SCOPUS:33646153766
SN - 0032-3861
VL - 47
SP - 3520
EP - 3527
JO - Polymer
JF - Polymer
IS - 10
ER -