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Title: Insights into the Thermal Expansion of Amorphous Polymers

Journal Article · · ACS Macro Letters
 [1];  [1];  [1]; ORCiD logo [2];  [3]; ORCiD logo [4]; ORCiD logo [1]
  1. Yonsei Univ., Seoul (Korea, Republic of)
  2. Korea Research Institute of Chemical Technology (KRICT), Daejeon (Korea, Republic of)
  3. Hyundai Motor Group, Uiwang (Korea, Republic of)
  4. Univ. of Massachusetts, Amherst, MA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Here, we investigated the thermal expansion of amorphous polystyrene (PS) and poly(methyl methacrylate) (PMMA) homopolymers using the temperature dependence of spatial electron-density correlations. The strong and broad X-ray interference maxima arising from inter- and intramolecular correlation distances were distinct, maintaining their shape during the heating of the samples to 250 °C. Three maxima characteristic of electron density correlations between the backbones, substituents along the chain, and repeat-units were observed. A remarkable temperature dependence was identified in the largest correlation distances arising from the intermolecular interactions. Based on the temperature dependence of the correlation distances, the coefficients of molecular expansion were very close to the coefficients of thermal expansion. This study provides a simple yet accurate way to correlate macroscopic volume expansions with the molecular expansion obtained from wide-angle X-ray scattering (WAXS) data.

Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
National Research Foundation of Korea (NRF); US Air Force Office of Scientific Research (AFOSR); USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
AC02-05CH11231
OSTI ID:
2475777
Journal Information:
ACS Macro Letters, Journal Name: ACS Macro Letters Journal Issue: 11 Vol. 13; ISSN 2161-1653
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English

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