Methanol assisted-massive production of surfactant-free ordered honeycomb polycaprolactone film

Abstract

Highly ordered honeycomb films made of biocompatible and biodegradable polymers are in pivotal demand for human-related applications such as tissue engineering and drug delivery. Among several common methods to form these honeycomb-structured films, Breath Figure methods (BFs) are widely used, which usually requires additional surface-active agents and strictly controlled humidity condition. Therefore, it is deficient to utilize BFs for practical applications of intensively used bioresorbable polymers such as polycaprolactone. Herein, we propose a new two-step method to not only surmount the mentioned weakness of BFs but also for the first time produce super-large honeycomb polycaprolactone (hc-PCL) film in the normal indoor environment. In our new method, methanol is exploited to induce a nanoparticle-like layer on the surface of droplets to prevent them from coalescence, which facilitates the formation of the uniformly ordered honeycomb structures. The results showed that the hc-PCL film was successfully fabricated with a large area of up to 5⋅5 cm2 with the pore size tuned in a range of 1÷7 μm. Moreover, by applying the method, the honeycomb structures were successfully imprinted onto non-planar PCL films as well as 3D printed PCL substrate. We believe that the convergence of excellent bio-compatibility and scalable production, as well as ease of turning pattern features would enable new prospects of the hc-PCL to widely be applied in biotechnology with multi-functionality and low-cost production.