TY - JOUR
T1 - Major roles of blend partner fragility and dye placement on component glass transition temperatures
T2 - Fluorescence study of near-infinitely dilute species in binary blends
AU - Evans, Christopher M.
AU - Torkelson, John M.
PY - 2012/10/23
Y1 - 2012/10/23
N2 - We measure the glass transition temperatures (T gs) of near-infinitely dilute (0.1 wt %), well-dispersed polystyrene (PS) components in seven blend partners using intrinsic and extrinsic fluorescence. The PS T gs span a 150 °C range when PS is dispersed in partners with T gs of -6 to 150 °C. We calculate self-concentrations for PS (β self PS) of ∼0 to 0.72 via the Lodge-McLeish model, the largest range ever reported for a blend component. Our study reveals that perturbations to PS T g, which may be quantified by β self PS calculations, correlate with partner fragility rather than partner T g, with higher fragility partners resulting in higher β self PS values. In particular, for 0.1 wt % PS in poly(vinyl chloride) (PVC), the partner with the highest reported fragility but an intermediate T g, the PS T g is only weakly perturbed with β self PS = 0.72. These results indicate that partner fragility plays a key role in determining the strength of T g perturbations to a blend component. Also noteworthy is 0.1 wt % PS in poly(4-vinylpyridine) (P4VP) where the PS T g is slaved to that of P4VP (β self PS ∼ 0). Fluorescent label location on the backbone does not significantly influence the measured T g. However, the distance separating a label from the backbone is crucial in determining T g and thereby β self PS. In PVC, β self PS decreases from 0.72 to ∼0 when a dye is attached to the PS backbone by a methyl ester or butyl ester group, respectively, indicating a highly heterogeneous environment within ∼0.45 nm of the backbone.
AB - We measure the glass transition temperatures (T gs) of near-infinitely dilute (0.1 wt %), well-dispersed polystyrene (PS) components in seven blend partners using intrinsic and extrinsic fluorescence. The PS T gs span a 150 °C range when PS is dispersed in partners with T gs of -6 to 150 °C. We calculate self-concentrations for PS (β self PS) of ∼0 to 0.72 via the Lodge-McLeish model, the largest range ever reported for a blend component. Our study reveals that perturbations to PS T g, which may be quantified by β self PS calculations, correlate with partner fragility rather than partner T g, with higher fragility partners resulting in higher β self PS values. In particular, for 0.1 wt % PS in poly(vinyl chloride) (PVC), the partner with the highest reported fragility but an intermediate T g, the PS T g is only weakly perturbed with β self PS = 0.72. These results indicate that partner fragility plays a key role in determining the strength of T g perturbations to a blend component. Also noteworthy is 0.1 wt % PS in poly(4-vinylpyridine) (P4VP) where the PS T g is slaved to that of P4VP (β self PS ∼ 0). Fluorescent label location on the backbone does not significantly influence the measured T g. However, the distance separating a label from the backbone is crucial in determining T g and thereby β self PS. In PVC, β self PS decreases from 0.72 to ∼0 when a dye is attached to the PS backbone by a methyl ester or butyl ester group, respectively, indicating a highly heterogeneous environment within ∼0.45 nm of the backbone.
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U2 - 10.1021/ma3014614
DO - 10.1021/ma3014614
M3 - Article
AN - SCOPUS:84867758326
SN - 0024-9297
VL - 45
SP - 8319
EP - 8327
JO - Macromolecules
JF - Macromolecules
IS - 20
ER -