TY - JOUR
T1 - Self and collective dynamics of ordered star polymer solutions
AU - Stellbrink, J.
AU - Allgaier, J.
AU - Monkenbusch, M.
AU - Richter, D.
AU - Ehlers, G.
AU - Schleger, P.
PY - 2002/12
Y1 - 2002/12
N2 - We investigated the dynamics of 18-arm poly-isoprene star polymer solutions well above their overlap concentration c*. Combining neutron spin echo spectroscopy (NSE) and selective H/D labelling, we were able to separate inter- (collective) and intra-star (self) dynamics. Only at low Q-vectors do self and collective dynamics become discernible. Here, collective dynamics are found to be consistent with a colloidal approach resulting from star-star interactions. The collective short time diffusion coefficient Deff is well described by the term D0/S(Q), with D0 the diffusion coefficient at infinite dilution. At Qm, the peak position in the structure factor S(Q), no difference is observable between collective and self dynamics. For covering the slowed-down dynamics at Qm the time range of NSE was extended for the first time up to 350 nms using long wavelengths, λ = 19 Å, at IN15 (ILL, Grenoble). We found that S(Q, t)/S (Q, 0) relaxes into a concentration-dependent plateau. The plateau height gives the mean-square displacement < r2 >1/2 of star cores, which is related to the blob size ξ of the surrounding star polymer solution obtained by dynamic light scattering.
AB - We investigated the dynamics of 18-arm poly-isoprene star polymer solutions well above their overlap concentration c*. Combining neutron spin echo spectroscopy (NSE) and selective H/D labelling, we were able to separate inter- (collective) and intra-star (self) dynamics. Only at low Q-vectors do self and collective dynamics become discernible. Here, collective dynamics are found to be consistent with a colloidal approach resulting from star-star interactions. The collective short time diffusion coefficient Deff is well described by the term D0/S(Q), with D0 the diffusion coefficient at infinite dilution. At Qm, the peak position in the structure factor S(Q), no difference is observable between collective and self dynamics. For covering the slowed-down dynamics at Qm the time range of NSE was extended for the first time up to 350 nms using long wavelengths, λ = 19 Å, at IN15 (ILL, Grenoble). We found that S(Q, t)/S (Q, 0) relaxes into a concentration-dependent plateau. The plateau height gives the mean-square displacement < r2 >1/2 of star cores, which is related to the blob size ξ of the surrounding star polymer solution obtained by dynamic light scattering.
UR - http://www.scopus.com/inward/record.url?scp=0037003496&partnerID=8YFLogxK
U2 - 10.1007/s003390201627
DO - 10.1007/s003390201627
M3 - Article
AN - SCOPUS:0037003496
SN - 0947-8396
VL - 74
SP - S361-S363
JO - Applied Physics A: Materials Science and Processing
JF - Applied Physics A: Materials Science and Processing
IS - SUPPL.I
ER -