Nanocomposites of Poly(hydroxyurethane)s with Multiwalled Carbon Nanotubes: Synthesis, Shape Memory, and Reprocessing Properties

Abstract

Poly­(hydroxyurethane)­s (PHUs) are synthesized via non-isocyanate approaches and could be the potential alternatives of conventional polyurethanes. It is of importance to investigate the structure–property relationship of PHUs. In this work, we investigated the PHU nanocomposites containing multiwalled carbon nanotubes (CNTs). First, CNTs were functionalized with poly­(acryloyl carbonate), a polymer bearing 6-membered cyclic carbonate groups (denoted PA6CC) via the surface reversible addition–fragmentation chain transfer polymerization approach. Thereafter, the PA6CC-grafted CNTs were dispersed in the mixtures of 6-membered bicyclic carbonate (6BCC) and tris­(2-aminoethyl)­amine. By initiating the curing reaction, the nanocomposites were successfully obtained with the content of CNTs up to 11 wt %. The morphological investigation showed that CNTs were well dispersed in the PHU matrix; the CNTs preserved good integrity. The PHU nanocomposites displayed a series of improved thermomechanical properties in terms of glass transition temperatures (T g’s), tensile mechanical properties, and thermal conductivity. Compared to plain PHU thermoset, the PHU nanocomposites possessed enhanced dielectric constants and low dielectric loss. Owing to the introduction of CNTs, the nanocomposites displayed improved shape memory properties. It was found that the nanocomposites preserved reprocessing properties at elevated temperatures as plain PHU. The reprocessing properties bestowed the shape memory materials with reprograming ability of original shapes.

Nanocomposites of Polyhydroxyurethane with POSS Microdomains: Synthesis via Non-Isocyanate Approach, Morphologies and Reprocessing Properties

“…The incorporation of inorganics in organic polymers is an important technique to develop materials with excellent comprehensive properties. Recently, organic-inorganic nanocomposites of PHU with various inorganic nanoparticles have been also reported; the nanocomposites possess enhanced thermal, mechanical properties, and other specific properties [ 37 , 38 , 39 , 40 ]. For instance, Zheng et al [ 37 ] reported PHU/carbon nanotubes (CNTs) nanocomposites.…”

“…Recently, organic-inorganic nanocomposites of PHU with various inorganic nanoparticles have been also reported; the nanocomposites possess enhanced thermal, mechanical properties, and other specific properties [ 37 , 38 , 39 , 40 ]. For instance, Zheng et al [ 37 ] reported PHU/carbon nanotubes (CNTs) nanocomposites. Notably, the incorporation of CNTs significantly improved the mechanical and dielectric properties of PHU.…”

Polythiourethanes Crosslinked with Dynamic Disulfide Bonds: Synthesis via Nonisocyanate Approach, Thermomechanical and Reprocessing Properties

“…This crosslinking strategy is in marked contrast to those to crosslink PTUs (or PHUs) with multifunctional amines or cyclic carbonates as the crosslinkers. [ 21–27 ] Shown in Figure are the Fourier transform infrared (FTIR) spectra of 1 , PMTU‐PPO430, c ‐PTU‐PPO430, and the recovered PTMU‐PPO430 with sodium l ‐ascorbate. For 1 , the stretching vibration of SC< bond was detected at 1736 cm −1 and that of the S–C–S linkage occurred at 1674 cm −1 .…”

“…In recent years, the chemistries, structures, and properties of PHUs have been extensively investigated. [ 10–27 ] Of cyclic carbonates that are used to obtain PHUs, five‐membered cyclic monomers are readily synthesized via the reaction of epoxides with carbon dioxide (CO 2 ) with high yields. [ 6–8 ] Similarly, carbon sulfide (CS 2 ) can be used to synthesize five‐membered cyclic carbonates with its reaction with epoxide groups.…”

Glycerol carbonate methacrylate: A cross-linking agent for hydroxyurethane-acrylate coatings

“…[76]Moreover, the reversibility of the hydroxyurethane linkage formed by TAEA is even easier compare to other amines and may occur at relatively low temperatures. [77,78] Additionally, a small amount of unreacted TAEA may be present in the material. On the other hand, the cross-linked copolymers with higher BA ratios exhibited higher 5% weight loss temperature values, following the same behavior that the uncured copolymers and previously observed by Kumar Konaganti et al [74] for BA/MMA copolymers.…”