Direct Laser Writing to Generate Molds for Polymer Nanopillar Replication

Abstract

Herein we exploit direct laser writing as a means to fabricate negative masters for the generation of polymeric nanopillars, via replica molding. Through optimization of design parameters, fabrication configuration, and polymerization protocols, we demonstrate for the first time, the fabrication of large-area negative templates which can be used to repeatedly produce some of the tallest (>1.5 µm) and thinnest (<300 nm) pillars ever achieved in biocompatible photocurable polymers, such as polyethylene glycol diacrylate, polypropylene glycol diacrylate, and polycaprolactone dimethacrylate. This combination serves to add value to two photon polymerization, and to extend its potential to the facile production of millimeter-sized arrays of submicron pillars, of infinite combinations of height, diameter and pitch in a wide variety of compliant, biocompatible, and biodegradable materials.

Controlled degradation of polycaprolactone-based micropillar arrays

“…53 The viscosity of the blend prior to replication was an important consideration for NIL. 49,54 As the ratio of HDDA increased and PCLDMA decreased in the liquid monomer, the viscosities were reduced (15.5 cP and 10.8 cP for 20%PH and 10%PH, respectively). After photopolymerisation under white light, FTIR analysis was performed to confirm complete polymerisation (Figures S3-5), where for all 3 samples, as the curing progressed over 0-120 mins, an incremental increase in transmission for the peaks at 1620 cm -1 and 1638 cm -1 was observed, which related to a reduction in C=C acrylate bond stretching as the polymerisation occurred.…”

“…Open Herein, we extend on our previous work, which combined direct laser writing using 2 photon polymerisation (2PP) with nanoimprint lithography (NIL) to generate 3D microstructures. 49 Our previous work studied the writing parameters which we needed to generate stable pore templates from which high aspect ratio micropillar arrays could be molded using photocurable polymers. We have advanced on this by producing large array templates, as well as dual height pore templates in this work.…”

Biomimetic Polymer Surfaces by High Resolution Molding of the Wings of Different Cicadas

“…Longer chain length, difference in moduli, surface free energy and polar fractions of PPGDA compared to PEGDA were all anticipated to aid in mold separation [ 37 , 58 , 59 ]. In other work carried out in our group, there was a difference in Young’s moduli exhibited after AFM force mapping when comparing PPG (374 ± 41 MPa) to PEG (765 ± 73 MPa) [ 60 ]. Surface free energy (SFE) measurements on planar gels confirmed the SFE of planar PPG was lower than that of planar PEG using our method (47 ± 3 mN·m −1 vs. 62 ± 2 mN·m −1 ); see Supplementary Materials Table S1 .…”

Light‐Powered Microrobots: Challenges and Opportunities for Hard and Soft Responsive Microswimmers

“…Biocompatibility is an underlying stringent requirement for all the envisioned applications mentioned herein, and the need for biocompatible materials is becoming more and more evident nowadays. [180,207] While some noncytotoxic photoresists for 2PP are already available, such as IP-Visio and Ormosil, more commercial and in-house biocompatible formulations are being developed. Environmental applications should be extremely interesting for swarms of sun-powered microrobots.…”