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Title: Synthesis of polycaprolactone-polyimide-polycaprolactone triblock copolymers via a 2-step sequential copolymerization and their application as carbon nanotube dispersants
Authors: Liu, Chengyin
Liu, Bo
Chan-Park, Mary B.
Keywords: Carbon Nanotube Dispersants
Triblock Copolymers
Issue Date: 2017
Source: Liu, C., Liu, B., & Chan-Park, M. B. (2017). Synthesis of polycaprolactone-polyimide-polycaprolactone triblock copolymers via a 2-step sequential copolymerization and their application as carbon nanotube dispersants. Polymer Chemistry, 8(4), 674-681.
Series/Report no.: Polymer Chemistry
Abstract: Polyimides have attractive properties such as a strong interaction with 1D/2D carbon nanomaterials but their solubilities in common organic solvents are limited. We report a new synthesis route for triblock copolymers of polycaprolactone-polyimide-polycaprolactone (PCL-PI-PCL) via polycondensation followed by ring-opening polymerization. The prepared OH-PI-OH homopolymer precursors were reacted with two equivalents of stannous(II) octoate (Sn(Oct)2) to afford α,ω-dihydroxyl-terminated polyimide macroinitiators which can polymerize with ε-caprolactone to obtain the final triblock copolymers (PCL-PI-PCL). Four different molecular weights of PCL-PI-PCL triblock copolymers with different lengths of PCL and PI blocks were synthesized to assess the best composition for carbon nanotube dispersion in a low boiling organic solvent (tetrahydrofuran, THF). The polyimide block interacts strongly with single walled carbon nanotubes (SWNTs) through charge transfer, as shown by Raman spectroscopy, while the polycaprolactone block has a good solubility in THF. An optimised triblock copolymer disperses the carbon nanotubes in THF well even after standing for 1 h, while the PI homopolymer-dispersed SWNTs settled completely under the same conditions. We applied the new PCL-PI-PCL in SWNT-reinforced epoxy composites with the use of THF as the casting solvent. The optimised triblock copolymer-dispersed SWNTs (2 wt%) increased the tensile strength, modulus, and elongation at maximum stress by 74%, 35%, and 62% respectively compared to the neat resin blend. The new synthesis route of the triblock copolymer is amenable to the synthesis of diverse PI-based triblock copolymers with various desired functionalities for myriad applications, such as for carbon nanotube-reinforced epoxy-based composites, water-based antibacterial dispersions, etc.
ISSN: 1759-9954
DOI: 10.1039/C6PY01933A
Schools: School of Chemical and Biomedical Engineering 
Lee Kong Chian School of Medicine (LKCMedicine) 
Rights: © 2017 The Royal Society of Chemistry. This is the author created version of a work that has been peer reviewed and accepted for publication by Polymer Chemistry, The Royal Society of Chemistry. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [].
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:SCBE Journal Articles

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