Electroactive shape memory polyurethane composites reinforced with octadecyl isocyanate-functionalized multi-walled carbon nanotubes

Yadong Sun; Jiachi Teng; Yi Kuang; Shengxiang Yang; Jiquan Yang; Hongli Mao; Zhongwei Gu

doi:10.3389/fbioe.2022.964080

Electroactive shape memory polyurethane composites reinforced with octadecyl isocyanate-functionalized multi-walled carbon nanotubes

Front Bioeng Biotechnol. 2022 Jul 15:10:964080. doi: 10.3389/fbioe.2022.964080. eCollection 2022.

Authors

Yadong Sun¹, Jiachi Teng¹, Yi Kuang², Shengxiang Yang², Jiquan Yang³, Hongli Mao^{1

4}, Zhongwei Gu^{1

4}

Affiliations

¹ Research Institute for Biomaterials, Tech Institute for Advanced Materials, College of Materials Science and Engineering, Nanjing Tech University, Nanjing, China.
² College of Chemical and Materials Engineering, Zhejiang A&F University, Lin'an, China.
³ Nanjing Industry Institute for Advanced Intelligent Equipment, Nanjing, China.
⁴ NJTech-BARTY Joint Research Center for Innovative Medical Technology, Nanjing, China.

Abstract

Shape memory polymers (SMPs) have a wide range of potential applications in many fields. In particular, electrically driven SMPs have attracted increasing attention due to their unique electrical deformation behaviors. Carbon nanotubes (CNTs) are often used as SMP conductive fillers because of their excellent electrical conductivities. However, raw CNTs do not disperse into the polymer matrix well. This strictly limits their use. In this study, to improve their dispersion performance characteristics in the polymer matrix, hydroxylated multi-walled carbon nanotubes (MWCNT-OHs) were functionalized with octadecyl isocyanate (i-MWCNTs). Polyurethane with shape memory properties (SMPU) was synthesized using polycaprolactone diol (PCL-diol), hexamethylene diisocyanate (HDI), and 1,4-butanediol (BDO) at a 1:5:4 ratio. Then, electroactive shape memory composites were developed by blending SMPU with i-MWCNTs to produce SMPU/i-MWCNTs. The functionalized i-MWCNTs exhibited better dispersibility characteristics in organic solvents and SMPU composites than the MWCNT-OHs. The addition of i-MWCNTs reduced the crystallinity of SMPU without affecting the original chemical structure. In addition, the hydrogen bond index and melting temperature of the SMPU soft segment decreased significantly, and the thermal decomposition temperatures of the composites increased. The SMPU/i-MWCNT composites exhibited conductivity when the i-MWCNT content was 0.5 wt%. This conductivity increased with the i-MWCNT content. In addition, when the i-MWCNT content exceeded 1 wt%, the composite temperature could increase beyond 60°C within 140 s and the temporary structure could be restored to its initial state within 120 s using a voltage of 30 eV. Therefore, the functionalized CNTs exhibit excellent potential for use in the development of electroactive shape memory composites, which may be used in flexible electronics and other fields.

Keywords: electroactive; functionalization; multi-walled carbon nanotubes; octadecyl isocyanate; shape memory polyurethane.