THESIS
2021
1 online resource (xxv, 183 pages) : illustrations (some color)
Abstract
This project was aimed to investigate the confinement of micelle-forming triblock
copolymer of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO)
in high-strength ultrahigh molecular weight polyethylene membrane (UHMWPE), and the
resultant composite membrane of PEO-PPO-PEO/UHMWPE. Poor mechanical strength of PEO-PPO-PEO was improved by impregnating the copolymer into the UHMWPE membrane. At the
same time, the inherent hydrophobicity of UHMWPE membrane was altered to become
amphiphilic membrane rendering broader applications particularly in biomedical area. The
change in hydrophobicity was evidenced by the contact angle which significantly reduced from
129.0° to 31.8° in the presence of PEO-PPO-PEO. The composite membrane of UHMWPE/PEO-PPO-PEO showed intriguing...[
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This project was aimed to investigate the confinement of micelle-forming triblock
copolymer of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO)
in high-strength ultrahigh molecular weight polyethylene membrane (UHMWPE), and the
resultant composite membrane of PEO-PPO-PEO/UHMWPE. Poor mechanical strength of PEO-PPO-PEO was improved by impregnating the copolymer into the UHMWPE membrane. At the
same time, the inherent hydrophobicity of UHMWPE membrane was altered to become
amphiphilic membrane rendering broader applications particularly in biomedical area. The
change in hydrophobicity was evidenced by the contact angle which significantly reduced from
129.0° to 31.8° in the presence of PEO-PPO-PEO. The composite membrane of UHMWPE/PEO-PPO-PEO showed intriguing confinement crystallization behavior where PEO under confinement
in UHMWPE membrane changes from crystalline to amorphous as evidenced by the presence of
the absorption band at 1349 cm
-1 as well as the broad peak in the FTIR spectra, and the lack of
the melting and crystallization transitions in DSC thermograms above room temperature. The
confinement led to a significant shift of the crystallization temperature of PEO from 32.8 °C to a
significantly lower temperature at around -19 °C because the crystallization mechanism changed
from heterogeneous nucleation to homogeneous nucleation‒similar to those reported in anodic
aluminum oxide (AAO) nano-templates. In addition, a substantial reduction in crystallinity was
observed when the copolymer was under confinement of the membrane. The disordered PEO or
amorphization of PEO under confinement of porous UHMWPE membrane has potential application in solid-state battery application as a membrane separator. The confinement of PEO
in UHMWPE membrane distinguishes itself from that in the AAO system in a way that the
system reported in this study allows accurate crystallinity determination which leads to better
understanding in crystallization process under confinement. In addition, the membrane provides
cleaner specimen leaving no trace of non-confined PEO, larger DSC signal, and it can be directly
applied as a separator in the solid-state battery application.
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