Abstract
Relaxation calorimetry experiments were used to measure the temperature dependence of the heat capacity near the order-disorder phase transition (ODT) in a low molecular weight volumetrically symmetric, lamellae-forming, poly(1,4-isoprene-b-dl-lactide) diblock copolymer with Mn = 2750 g/mol (dispersity cross sign D = 1.10) and composition fPLA = 0.51. This enabled accurate determination of the latent heat of the ODT, yielding a value ΔHODT = 0.26 ± 0.02 J/g, consistent with previous measurements using differential scanning calorimetry. The relatively small magnitude of the latent heat supports the results of recent molecular simulations and reinforces the importance of composition fluctuations on the thermodynamics of block polymers near the ODT. These thermal measurements reveal no signature of the fluctuation effects in the disordered state as T → TODT, consistent with previous experimental and theoretical work, which supports the notion that composition fluctuations develop over a relatively wide range of temperatures for T > TODT. The finite width of the heat capacity peak, ΔTODT ≈ 1 °C, is shown to be consistent with molecular dispersity. These measurements demonstrate the utility of relaxation calorimetry as a quantitative semistatic thermal characterization tool for block polymers in the vicinity of phase transitions. (Graph Presented).
| Original language | English (US) |
|---|---|
| Pages (from-to) | 4733-4741 |
| Number of pages | 9 |
| Journal | Macromolecules |
| Volume | 48 |
| Issue number | 13 |
| DOIs | |
| State | Published - Jul 14 2015 |
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Determination of the Lamellae-to-Disorder Heat of Transition in a Short Diblock Copolymer by Relaxation Calorimetry. / Gillard, Timothy M.; Phelan, Daniel; Leighton, Chris; Bates, Frank S.
In: Macromolecules, Vol. 48, No. 13, 14.07.2015, p. 4733-4741.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Determination of the Lamellae-to-Disorder Heat of Transition in a Short Diblock Copolymer by Relaxation Calorimetry
AU - Gillard, Timothy M.
AU - Phelan, Daniel
AU - Leighton, Chris
AU - Bates, Frank S.
PY - 2015/7/14
Y1 - 2015/7/14
N2 - Relaxation calorimetry experiments were used to measure the temperature dependence of the heat capacity near the order-disorder phase transition (ODT) in a low molecular weight volumetrically symmetric, lamellae-forming, poly(1,4-isoprene-b-dl-lactide) diblock copolymer with Mn = 2750 g/mol (dispersity cross sign D = 1.10) and composition fPLA = 0.51. This enabled accurate determination of the latent heat of the ODT, yielding a value ΔHODT = 0.26 ± 0.02 J/g, consistent with previous measurements using differential scanning calorimetry. The relatively small magnitude of the latent heat supports the results of recent molecular simulations and reinforces the importance of composition fluctuations on the thermodynamics of block polymers near the ODT. These thermal measurements reveal no signature of the fluctuation effects in the disordered state as T → TODT, consistent with previous experimental and theoretical work, which supports the notion that composition fluctuations develop over a relatively wide range of temperatures for T > TODT. The finite width of the heat capacity peak, ΔTODT ≈ 1 °C, is shown to be consistent with molecular dispersity. These measurements demonstrate the utility of relaxation calorimetry as a quantitative semistatic thermal characterization tool for block polymers in the vicinity of phase transitions. (Graph Presented).
AB - Relaxation calorimetry experiments were used to measure the temperature dependence of the heat capacity near the order-disorder phase transition (ODT) in a low molecular weight volumetrically symmetric, lamellae-forming, poly(1,4-isoprene-b-dl-lactide) diblock copolymer with Mn = 2750 g/mol (dispersity cross sign D = 1.10) and composition fPLA = 0.51. This enabled accurate determination of the latent heat of the ODT, yielding a value ΔHODT = 0.26 ± 0.02 J/g, consistent with previous measurements using differential scanning calorimetry. The relatively small magnitude of the latent heat supports the results of recent molecular simulations and reinforces the importance of composition fluctuations on the thermodynamics of block polymers near the ODT. These thermal measurements reveal no signature of the fluctuation effects in the disordered state as T → TODT, consistent with previous experimental and theoretical work, which supports the notion that composition fluctuations develop over a relatively wide range of temperatures for T > TODT. The finite width of the heat capacity peak, ΔTODT ≈ 1 °C, is shown to be consistent with molecular dispersity. These measurements demonstrate the utility of relaxation calorimetry as a quantitative semistatic thermal characterization tool for block polymers in the vicinity of phase transitions. (Graph Presented).
UR - http://www.scopus.com/inward/record.url?scp=84937046376&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84937046376&partnerID=8YFLogxK
U2 - 10.1021/acs.macromol.5b00881
DO - 10.1021/acs.macromol.5b00881
M3 - Article
AN - SCOPUS:84937046376
VL - 48
SP - 4733
EP - 4741
JO - Macromolecules
JF - Macromolecules
SN - 0024-9297
IS - 13
ER -