Diverse nature of femtosecond laser ablation of poly(L-lactide) and the influence of filamentation on the polymer crystallization behaviour

• Published in: Scientific reports Vol. 9; no. 1; p. 3069
• Main Authors: Stępak, Bogusz, Gazińska, Małgorzata, Nejbauer, Michał, Stepanenko, Yuriy, Antończak, Arkadiusz
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 28-02-2019; Nature Publishing Group
• Subjects: 639/301/54/990; 639/624/1075; 639/766/25; Crystallization; Fabrication; Filamentation; Humanities and Social Sciences; Laser ablation; Lasers; Low temperature; multidisciplinary; Poly(L-lactide); Polylactic acid; Polymers; Science; Science (multidisciplinary); Wavelength
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-39640-1

Over the past few years we have witnessed growing interest in ultrafast laser micromachining of bioresorbable polymers for fabrication of medical implants and surface modification. In this paper we show that surface structuring of poly(L-lactide) with 300 fs laser pulses at 515 and 1030 nm wavelength leads to formation of defects inside the polymer as a result of laser beam filamentation. Filament-induced channels have diameter around 1 μm and length of hundreds of micrometers. SEM images of microchannels cross-sections are presented. The influence of wavelength and pulse spacing on bulk modification extent was investigated and parameters limiting filamentation were determined. We show that filamentation can be used for controlling properties of PLLA. The presence of filament-induced modifications such as empty microchannels and pressure wave-induced stress lead to increased ability of polymer to crystallize at lower temperature. Crystallization behaviour and crystal morphology after laser treatment was investigated in details using different analytical techniques such as WAXD, DSC and FTIR/ATR. Hydrolytic degradation experiment was performed. Presented method can be applied for controllable, spatially distributed modification of polymer crystallinity, crystalline phase structure and hydrolytic degradation profile.