Laser-Induced Microstructuring of Polymers in Gaseous, Liquid and Supercritical Media.

Alexey Rybaltovskii,Nikita Minaev,Svetlana Minaeva,Svetlana Tsypina,Vladimir Yusupov

doi:10.3390/polym13203525

Alexey Rybaltovskii, Nikita Minaev + Show 3 more

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https://doi.org/10.3390/polym13203525

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Abstract

New results are presented for laser formation—in particular, the “drawing” of microstructures in polymer films using continuous-wave (CW) laser radiation λ = 405 nm with an intensity of 0.8–3.7 kW/cm2. The laser drawing was carried out in the polymer system poly-2,2′-p-oxydiphenylene-5,5′-bis-benzimidazole (OPBI), which consists of two phases: a solid polymer matrix with formic acid (HCOOH) dissolved in it. The formation of microstructures, including the stage of foaming, was carried out in three media: air, water and a supercritical carbon dioxide medium containing dissolved molecules of the silver precursor Ag(hfac)COD. The morphological features of foam-like track structures formed in the near-surface layer of the polymer films by laser “drawing” are considered. A model of processes is presented that explains the appearance of periodic structures. The key point of this model is that it considers the participation of the photoinduced mechanism of explosive boiling of formic acid molecules dissolved in the polymer matrix. Using Raman spectroscopy, spectra were obtained and interpreted, which relate to different stages in the formation of microstructures in OPBI films. The effects associated with the peculiarities of luminescent microstructures on the surfaces of glasses in close contact with polymer films during laser “painting” in the air have been studied.

Highlights

Over the past three decades, the formation of various microstructures in polymeric materials has been one of the most demanding problems, since its solution largely dictates the progressive development of such areas as biomedical and chemical technologies, polymer microphotonics and nanoplasmonics [1,2,3,4,5,6,7,8]
Femtosecond laser radiation was used on the surfaces of polymers containing dye impurities [5] to obtain linear luminescent structures, which can be used to address problems associated with polymer microphotonics
We reported, for the first time, the presence of an intense luminescent glow arising on the surfaces of drying OPBI films [10], as well as in the regions of the films previously irradiated with focused continuous laser radiation with λ = 405 nm [9]

Summary

Introduction

Over the past three decades, the formation of various microstructures in polymeric materials has been one of the most demanding problems, since its solution largely dictates the progressive development of such areas as biomedical and chemical technologies, polymer microphotonics and nanoplasmonics [1,2,3,4,5,6,7,8]. In our works [9,10], the possibility of the formation of luminescent surface microstructures in polymeric materials based on polybenzimidazoles, namely in films of poly-2,2 p-oxydiphenylene-5,5 -bis-benzimidazole (OPBI), was considered for the first time. They had a unique combination of properties: high thermal and chemical resistance, as well as good mechanical strength [11]. It was shown that the thermal destruction of OPBI films occurs at temperatures above 500 ◦C [12], making it possible to use this material to create a wide range of products for mechanical engineering

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