TY - JOUR
T1 - Ultrastable Glassy Polymer Films with an Ultradense Brush Morphology
AU - Zuo, Biao
AU - Li, Cheng
AU - Xu, Quanyin
AU - Randazzo, Katelyn
AU - Jiang, Naisheng
AU - Wang, Xinping
AU - Priestley, Rodney D.
N1 - Funding Information:
B.Z. and X.W. thank the support from the National Natural Science Foundation of China (21973083, 22011530456, and 21674100). R.D.P. gratefully acknowledges the National Science Foundation (NSF) Materials Research Science and Engineering Center Program through the Princeton Center for Complex Materials (DMR-1420541 and 2011750) and through CBET-1706012. The authors also thank Ruipeng Li and Masafumi Fukuto for assisting the synchrotron X-ray scattering measurements. This research used the Complex Materials Scattering (CMS/11-BM) beamline, operated by the National Synchrotron Light Source II at Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-SC0012704.
Publisher Copyright:
©
PY - 2021/6/22
Y1 - 2021/6/22
N2 - Glassy polymer films with extreme stability could enable major advancements in a range of fields that require the use of polymers in confined environments. Yet, from a materials design perspective, we now know that the glass transition temperature (Tg) and thermal expansion of polymer thin films can be dramatically different from those characteristics of the bulk, i.e., exhibiting confinement-induced diminished thermal stability. Here, we demonstrate that polymer brushes with an ultrahigh grafting density, i.e., an ultradense brush morphology, exhibit a significant enhancement in thermal stability, as manifested by an exceptionally high Tg and low expansivity. For instance, a 5 nm thick polystyrene brush film exhibits an ∼75 K increase in Tg and ∼90% reduction in expansivity compared to a spin-cast film of similar thickness. Our results establish how morphology can overcome confinement and interfacial effects in controlling thin-film material properties and how this can be achieved by the dense packing and molecular ordering in the amorphous state of ultradense brushes prepared by surface-initiated atom transfer radical polymerization in combination with a self-assembled monolayer of initiators.
AB - Glassy polymer films with extreme stability could enable major advancements in a range of fields that require the use of polymers in confined environments. Yet, from a materials design perspective, we now know that the glass transition temperature (Tg) and thermal expansion of polymer thin films can be dramatically different from those characteristics of the bulk, i.e., exhibiting confinement-induced diminished thermal stability. Here, we demonstrate that polymer brushes with an ultrahigh grafting density, i.e., an ultradense brush morphology, exhibit a significant enhancement in thermal stability, as manifested by an exceptionally high Tg and low expansivity. For instance, a 5 nm thick polystyrene brush film exhibits an ∼75 K increase in Tg and ∼90% reduction in expansivity compared to a spin-cast film of similar thickness. Our results establish how morphology can overcome confinement and interfacial effects in controlling thin-film material properties and how this can be achieved by the dense packing and molecular ordering in the amorphous state of ultradense brushes prepared by surface-initiated atom transfer radical polymerization in combination with a self-assembled monolayer of initiators.
KW - glass transition
KW - polymer brushes
KW - thermal expansion
KW - thin polymer films
KW - ultrastable polymer glasses
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U2 - 10.1021/acsnano.0c09631
DO - 10.1021/acsnano.0c09631
M3 - Article
C2 - 34032418
AN - SCOPUS:85108403608
SN - 1936-0851
VL - 15
SP - 9568
EP - 9576
JO - ACS Nano
JF - ACS Nano
IS - 6
ER -