Batman’s Memory Cloth Cape: too good but almost true

In Cbatman moviehristopher Nolan’s movie Batman Begins (2005), the caped crusader “Batman” used his cape that transforms into a glider to enter and exit several scenes.

In the story, Lucius Fox of the Applied Sciences division of Wayne Enterprises introduced the “memory fabric technology”. This fabric is a flexible material that stiffens when Batman batman movie exceptpasses an electric current through it from microcircuits in his right-hand glove turning it into bat wings like glider.

The general concept of Batman’s cape was not far cry from reality. It was in fact a visualization of one of the future potential applications of “Electroactive Shape Memory Polymers (SMP)” [1], [2]. However; the current developments in SMP will not be sufficient for Batman’s purposes. In my opinion, if Batman hypothetically used today’s SMP technology, he’ll be jumping straight to his coffin. Another related material worth mentioning includes Shape Memory Alloys. Thought, these alloys were not the same as the fabric material concept of the cape, it does alter it’s shape under specific conditions e.g. heat.

EASMP

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Figure 2.  Pictures illustrating the electro-active shape recovery of carbon nanotube-reinforced hyperbranched polyurethane composites [2]

Recent vintages of SMP’s are composites containing conductive fillers[1] that alter properties such as mechanical, modulus, thermal, magnetic and etc. According to Liu et’al [1], common fillers that causes ‘electroactivity’, or responsiveness to electricity, includes carbon nanotubes, electromagnetic fillers, Nickel chains, and Hybrid fibers. Samples of the latest SMP’s are shown on figures 1 and 2, both are multiwalled carbon nanotube fillers (MWCNT) in polyurethane, exhibiting their ability to return to their original shape by application of 40V of electricity in ca. 10s.

SMP’s with electromagnetic fillers are polymer-magnetite composites that responds to inductive heating. This is quite different from batman’s cape since inductive heating is more of a contactless electromagnetic phenomenon where heat is the main reason for the polymer’s reversion to its original permanent shape. Figure 3 shows the activity of SMP with electromagnetic filler.

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 Fig. 3. Photo series demonstrating the shape-memory transition induced by the impact of an HF electromagnetic field, measured from the top side of the induction coil. The shape of the sample is changed from helical (temporary shape) to a rectangular strip (permanent shape).

 

 

Innovations were made to other SMP’s by implanting nickel chains. These nickel chains are produced by adding nickel nanoparticles to the polymer matrix and curing under magnetic field. These nickel chains reduce electrical resistivity throughout the polymer thus increases shape recovery.

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Figure 4. Plot of Carbon Black (CB)-SMP  with and without Ni chain VS resistivity.

 

ASRGFigure 5. Sample (a) 10 volume fraction percent of CB, 0.5 volume fraction percent of chained Ni; sample (b) 10 volume fraction percent of CB, 0.5 volume fraction percent of randomly distributed Ni; and sample (c) 10 volume fraction percent of CB only.

 

Figure 4 reveals the relationship between CB content and electrical resistivity of SMP/CB/Ni(chained), SMP/CB/Ni random) and SMP/CB. It is clear that the additional 0.5 volume fraction percent of Ni, if distributed randomly, only slightly reduces the resistivity of the composites. However, at the same amount of Ni particles, if well-aligned to form chains, can significantly reduce the electrical resistivity by more than 10 times. Obviously, the remarkable reduction in the electrical resistivity is the result of the conductive chains, which serve as conductive channels to bridge those small isolated CB aggregations. This bridging effect is more significant in composites loaded with a low amount of CB in which the CB aggregates are relatively small in size and more isolated. As shown in Fig. 5, almost full recovery is observed in 120s.

Surely, given all these developments, we still can’t have a cape suitable for our 2005’s ‘Dark Knight’. On another note, other movie enthusiast critics how the wing span of the cape/glider is too small, it’s more like a wingsuit. Creating enough lift to make ‘batsy’ fly without hard impact is impossible. In addition, current SMP studies does not include tensile strength and hardness that makes an ideal glider. Disregarding the landing impact, the cape itself may not even be possible for years. Having such futuristic equipment those days are sure fit to be called Sci-Fi.

References:

[1] Liu, Y., Lv, H., Lan, X., Leng, J., & Du, S. (2009). Review of electro-active shape-memory polymer composite. Composites Science And Technology, 69(Smart Composites and Nanocomposites Special Issue with Regular Papaers), 2064-2068. doi:10.1016/j.compscitech.2008.08.016

[2] Mahapatra, S. S., Yadav, S. K., Yoo, H. J., Ramasamy, M. S., & Cho, J. W. (2014). Tailored and strong electro-responsive shape memory actuation in carbon nanotube-reinforced hyperbranched polyurethane composites. Sensors & Actuators: B. Chemical, 193384-390. doi:10.1016/j.snb.2013.12.006

[3] Batman begins [Motion picture]. (2005). Warner Home Video.