TY - JOUR
T1 - Understanding the influence of carbon nanotubes on the flow behavior of liquid crystalline hydroxypropylcellulose: A Rheo-NMR study
AU - Echeverria, Coro
AU - Almeida, Pedro L.
AU - Figueirinhas, João L.
AU - Godinho, Maria H.
N1 - info:eu-repo/grantAgreement/FCT/5876/147333/PT#
info:eu-repo/grantAgreement/FCT/SFRH/SFRH%2FBPD%2F88779%2F2012/PT#
M-ERA-NET2/0007/2016 (CellColor). P.L.A. acknowledges financial support from Portuguese Foundation for Science and Technology through the project PTDC/FIS-NAN/0117/2014.
J.L.F acknowledges financial support from Portuguese Foundation for Science and Technology through CeFEMA strategic project UID/CTM/04540/2019.
Spanish Ministry of Science, Innovation, and Universities for IJCI-2015-26432 contract.
PY - 2019/10/10
Y1 - 2019/10/10
N2 - Hydroxypropylcellulose (HPC) is an important cellulose derivative that has been widely studied due to its water-solubility, biocompatibility and biodegradability, but even more significant due to its ability to form liquid crystalline phases. HPC is able to form, under certain conditions, chiral nematic (cholesteric) structures in water solutions. Previous work confirmed that films prepared from liquid crystalline HPC/water solutions (LC-HPC) gave rise to anisotropic networks, with similar mechanical and optical characteristics of Liquid Crystalline Elastomers (LCE), capable to respond to humidity. It was also demonstrated that the incorporation of carbon nanotubes (CNTs) significantly improved the actuator responsiveness. In the work presented herein, we investigate how the incorporation of carbon nanotubes affects the flow behavior of LC-HPC solutions, and thus the structure-properties relationship, through a detailed Rheo-NMR study. As observed from the results, when shearing the samples, the degree of order reached (maximum quadrupolar peak splitting) by LC-HPC solutions increases with CNT content. Regarding the subsequent relaxation process, only the incorporation of 0.01 wt% of CNTs (lowest content) contributes to a faster recovery of cholesteric structure.
AB - Hydroxypropylcellulose (HPC) is an important cellulose derivative that has been widely studied due to its water-solubility, biocompatibility and biodegradability, but even more significant due to its ability to form liquid crystalline phases. HPC is able to form, under certain conditions, chiral nematic (cholesteric) structures in water solutions. Previous work confirmed that films prepared from liquid crystalline HPC/water solutions (LC-HPC) gave rise to anisotropic networks, with similar mechanical and optical characteristics of Liquid Crystalline Elastomers (LCE), capable to respond to humidity. It was also demonstrated that the incorporation of carbon nanotubes (CNTs) significantly improved the actuator responsiveness. In the work presented herein, we investigate how the incorporation of carbon nanotubes affects the flow behavior of LC-HPC solutions, and thus the structure-properties relationship, through a detailed Rheo-NMR study. As observed from the results, when shearing the samples, the degree of order reached (maximum quadrupolar peak splitting) by LC-HPC solutions increases with CNT content. Regarding the subsequent relaxation process, only the incorporation of 0.01 wt% of CNTs (lowest content) contributes to a faster recovery of cholesteric structure.
KW - Carbon nanotubes
KW - Cellulose
KW - LC-HPC
KW - Rheo-NMR
KW - Rheology
UR - http://www.scopus.com/inward/record.url?scp=85069833911&partnerID=8YFLogxK
U2 - 10.1016/j.polymer.2019.121675
DO - 10.1016/j.polymer.2019.121675
M3 - Article
AN - SCOPUS:85069833911
SN - 0032-3861
VL - 180
JO - Polymer
JF - Polymer
M1 - 121675
ER -