Photo-actuating materials based on elastomers and modified carbon nanotubes

Prestrain relaxation in non-covalently modified ethylene-vinyl acetate | PyChol | multiwall carbon nanotube nanocomposites

“…13 We tentatively attribute this shift to π -π interactions, as established between MWCNTs and PyChol, during high frequency sonication. 3 This proposal, however, is in disagreement with Kocharova et al, 18 who correlated π -π interactions in Single wall carbon nanotubes (SWCNTs) with an energy upshift in π * 2 C=C resonances. Albeit, π -π interactions are likely bonding mechanisms between MWCNT and PyChol, and good MWCNT dispersion and PyChol coverage was observed upon fabrication.…”

“…Albeit, π -π interactions are likely bonding mechanisms between MWCNT and PyChol, and good MWCNT dispersion and PyChol coverage was observed upon fabrication. 3 Further, π * 1 C=C showed no shift upon mixing, suggesting cholesteryl groups are not involved in MWCNT-PyChol interactions (Figure 2(a)). Indeed, the desired purpose of cholesteryl groups was to prevent MWCNT bundling by acting as "spacers."…”

“…5,6 Multiwall carbon nanotube (MWCNT) polymer composites are amongst the material systems prone to thermal actuation. 3 However, a major challenge in the fabrication of nanocomposites is achieving a homogeneous dispersion of nanotubes, since van der Waal forces promote nanotube bundling, interrupting a still-to-be-elucidated electronic dialog between fillers and matrix. 7 Although sonication and shear mixing are common dispersing procedures, they often result in nanotube fracture and surface damage.…”

“…1 In this scheme, thermal, optical, or electrical stimulus triggers a reversible change in dimension, that can be tailored to promote folding/unfolding in smart packaging, 2 raise/lower a microstructure for tactile perception, 3 and promote the contraction of an artificial muscle. 4 Albeit, the possibility of scaling the system from the nanometer to the macro-scale, as well as response to multiple stimuli, reversible character, and potential low cost are all attractive properties of smart nanocomposites in a range of fields, from Micro-Opto-Electro-Mechanical Systems (MOEMS) and nanotechnology to neuroscience and tissue engineering.…”

“…9 Photoactuation has recently been observed in ethylene-vinyl acetate | multiwall carbon nanotubes (EVA|MWCNT) composites, where dispersion of MWCNT was achieved by noncovalently bonding cholestryl 1-pyrenecarboxylate (PyChol) to pristine MWCNT walls. 3 In this scenario, the actuation mechanism was modelled as light being absorbed by MWCNTs and quickly being converted to local heat. Heat would then be transferred to surrounding polymeric chains, which would relax and contract, resulting in macroscopic mechanical actuation.…”