Size dependent nanomechanics of coil spring shaped polymer nanowires

Abstract

Direct laser writing (DLW) via two-photon polymerization (TPP) has been established as a powerful technique for fabrication and integration of nanoscale components, as it enables the production of three dimensional (3D) micro/nano objects. This technique has indeed led to numerous applications, including micro- and nanoelectromechanical systems (MEMS/NEMS), metamaterials, mechanical metamaterials, and photonic crystals. However, as the feature sizes decrease, an urgent demand has emerged to uncover the mechanics of nanosized polymer materials. Here, we fabricate coil spring shaped polymer nanowires using DLW via two-photon polymerization. We find that even the nanocoil springs follow a linear-response against applied forces, following Hooke’s law, as revealed by compression tests using an atomic force microscope. Further, the elasticity of the polymer material is found to become significantly greater as the wire radius is decreased from 550 to 350 nm. Polarized Raman spectroscopy measurements show that polymer chains are aligned in nanowires along the axis, which may be responsible for the size dependence. Our findings provide insight into the nanomechanics of polymer materials fabricated by DLW, which leads to further applications based on nanosized polymer materials.

Stress relaxation in polymeric microlattice materials

“…We find E ∞ = 2.22 ± 0.67GPa for the relaxed modulus of the photoresist IP-Dip™, used in the lattices fabrication. The predicted relaxed modulus agrees also well with previous works [42,47,48]. The linear factor C can be also used to extrapolate the microlattice viscoelastic properties if the base material is changed.…”

Dynamic Actuation of Soft 3D Micromechanical Structures Using Micro‐Electromechanical Systems (MEMS)

“…Methods to deform DLW microstructures such as atomic force microscopy (AFM), nanoindentation, parallel plate compression, swelling (for hydrogel structures), and probe station manipulation have all been reported . The more popular methods of AFM and nanoindentation can provide accurate force‐displacement information, which has been used to study mechanical behavior of the structures . With growing interest in using DLW across many different disciplines, additional methods for dynamic control of these structures are needed.…”

Optical Micromachines for Biological Studies

“…Optical microrobotics has been demonstrated to have applications in optical scanning-force microscopy [20], cell manipulation [21][22][23] and cell analysis [24]. The behaviour of optical micromachines has also been used to validate the use of classical mechanical models at the microscale [25,26] as well as providing insight into how material properties may be affected by scale [27]. However, optical micromachines have been under-utilised thus far in biological studies, making this area one with tremendous potential for researchers.…”