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

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.

Особенности Фокусировки Лазерного Излучения В Сверхкритическом Со-=sub=-2-=/Sub=-

“…54286.19362 В последнее время в качестве среды для лазерной абляции и микроструктурирования различных мишеней все шире используется сверхкритический диоксид углерода (sc-CO 2 ) [1][2][3]. Среда sc-CO 2 , уникальные свойства которой заключаются в высокой степени экологической чистоты, очень низкой вязкости, большой молекулярной подвижности и возможности оперативно изменять плотность в широких пределах, показала себя перспективной при получении гетерогенных катализаторов [4,5], синтезе наночастиц [6,7], получении уникальных полимерных материалов [3], микронизации лекарственных растений [8,9]. Еще одно неоспоримое преимущество sc-CO 2 заключается в том, что диоксид углерода переходит в сверхкритическое состояние при довольно низких значениях давления (7.38 MPa) и температуры (31.1 • C).…”

Features of focusing of a laser beam of laser ablation in supercritical carbo dioxidem

“…Supercritical carbon dioxide (sc-CO 2 ) is currently being used more and more often as a medium for laser ablation and microstructuring of various targets [1][2][3]. The sc-CO 2 medium, which is unique in being highly environmentally friendly, featuring very low viscosity and high molecular mobility values, and providing an opportunity for immediate adjustment of density within a wide range, was proven efficient in production of heterogeneous catalysts [4,5], nanoparticle synthesis [6,7], production of unique polymer materials [3], and micronization of medicinal plants [8,9]. Another undeniable advantage of sc-CO 2 consists in the fact that carbon dioxide becomes supercritical at fairly low values of pressure (7.38 MPa) and temperature (31.1 • C).…”