TY - JOUR
T1 - Comparison of surface mechanical properties among linear and star polystyrenes
T2 - Surface softening and stiffening at different temperatures
AU - Karim, Taskin B.
AU - McKenna, Gregory B.
N1 - Funding Information:
The authors acknowledge the National Science Foundation under grant CMMI-0928453 and the John R. Bradford Endowment at Texas Tech , each for significant funding of this work. We thank Prof. S.L. Simon and Dr. Y. P. Koh for DSC measurements and Yanfei Li for help in the rheometry.
PY - 2013/10/4
Y1 - 2013/10/4
N2 - In a previous study, we reported both surface softening and stiffening for poly(α-methylstyrene) (PαMS) over a temperature range from room temperature to 21 C above the glass transition temperature (Tg) using the spontaneous particle embedment technique. In the present study, we have explored the surface mechanical responses of a linear polystyrene (PS), a 3-arm star PS, and an 8-arm star PS emphasizing the range of temperature from T g -10 C to Tg +10 C, similar to that in which the prior study had shown a transition from surface softening (increased mobility) to stiffening (decreased mobility). We used atomic force microscopy for particle embedment depth estimation and the isochronal form of the Lee and Radok (LR) model for surface compliance determination. We observed both surface softening and stiffening for the linear PS and 3-arm star PS for the studied temperature range. However, surface softening was observed at all temperatures in this study for the 8-arm star PS. The surface compliance results for the different PS molecular architectures are compared with those for the linear PαMS from the previous study.
AB - In a previous study, we reported both surface softening and stiffening for poly(α-methylstyrene) (PαMS) over a temperature range from room temperature to 21 C above the glass transition temperature (Tg) using the spontaneous particle embedment technique. In the present study, we have explored the surface mechanical responses of a linear polystyrene (PS), a 3-arm star PS, and an 8-arm star PS emphasizing the range of temperature from T g -10 C to Tg +10 C, similar to that in which the prior study had shown a transition from surface softening (increased mobility) to stiffening (decreased mobility). We used atomic force microscopy for particle embedment depth estimation and the isochronal form of the Lee and Radok (LR) model for surface compliance determination. We observed both surface softening and stiffening for the linear PS and 3-arm star PS for the studied temperature range. However, surface softening was observed at all temperatures in this study for the 8-arm star PS. The surface compliance results for the different PS molecular architectures are compared with those for the linear PαMS from the previous study.
KW - Polystyrene
KW - Star branched polymers
KW - Surface mechanics
UR - http://www.scopus.com/inward/record.url?scp=84885019034&partnerID=8YFLogxK
U2 - 10.1016/j.polymer.2013.07.067
DO - 10.1016/j.polymer.2013.07.067
M3 - Article
AN - SCOPUS:84885019034
VL - 54
SP - 5928
EP - 5935
JO - Polymer
JF - Polymer
SN - 0032-3861
IS - 21
ER -