Borosilicate glass etches

WUes and Watts [48,53] have reported the use of a rather successful heterogenic catalytic system to carry out these reactions. They have tested a borosilicate glass microreactor (dimensions 3.0 x 3.0 x 0.6 cm) consisting of two etched layers with two inlets, mixing channels, a larger etched region and the outlet. A solid-supported catalyst was dry-packed in this structure (Fig. 4). 

Fig. 1. Secondary electron micrograph of Na-borosilicate glass loaded with 30 wt% waste oxides and containing 0.9 wt% S03 (etching with 0.1 M HC1). Droplets with chemical durability lower than matrix are a sulphate-enriched phase (Stefanovsky 1989).

This material also has a porous structure by virtue of its being made by etching a phase-separated borosilicate glass. PS chains have also been introduced into the pores of this type of glass [146], but the only results to date involve mechanical property measurements, and scattering investigations. 

Corman, T., Enoksson, P., Stemme, G., Deep wet etching of borosilicate glass using an anodically bonded silicon substrate as mask J. Micromech. Microeng. 1998, 8, 84-87. 

The devices are constructed from two plates, which are irreversibly joined by anodic bonding. M icrofabrication was achieved by means of deep reactive ion etching (DRIE) in borosilicate glass. 

R. O. Schwenker, Etch rate characterization of borosilicate glasses as diffusion sources, J. Electrochem. Soc. 118j 313, 1971. 

The so called porous silica is made by the acid etching of annealed sodium borosilicate glass. The bulk structure is glass mainly of silica and has a uniform pore size distribution in the mesopore region. These are used as a source of silica glass. 

A more recent example of enzyme-catalyzed synthesis performed in micro reactors was reported by Rutjes and co-workers [81], who demonstrated the use of crude enzyme lysates, containing hydroxynitrile lyase, for the enantioselective synthesis of cyanohydrins. Employing a wet-etched borosilicate glass micro reaction channel, containing pillars to promote biphasic laminar flow, the authors evaluated the... 

Jorgenson, J.W. Guthrie, E.J. Liquid chromatography in open-tubular columns Theory of column optimization with limited pressure and analysis time, and fabrication of chemically bonded reversed-phase columns on etched borosilicate glass capillaries. J. Chromatogr. 1983, 255, 335-348. 

In 1961 — 1962 Mohnke and Saffert [16] obtained a silica layer on borosilicate glass capillaries after prolonged (30 h) etching of the inner surface of... 

Patents [102, 103] describe the preparation of open tubular columns with an inside thickness-fixed porous layer by etching. First, the authors prepared a capillary column from a two-layer workpiece composed of two concentric tubes, one of them (external) being made of sodium borosilicate glass. To obtain an adsorption layer of defined thickness, the inner layer of the two-layer capillary was entirely leached. The method relies on porous glasses as the adsorbents. Porous glasses have been successfully used in gas capillary (see, for example, [104]). 

Akashi T, Yoshimura Y (2006) Deep reactive ion etching of borosilicate glass using an anodically bonded silicon wafer as an etch mask. J Micromech Microeng 16 1051... 

Borosilicate glasses are also (like silica glass) very susceptible to attack by hydrofluoric acid. The mechanism is the same as for quartz glass and is described in Sect. 1.2.1. HF is used for polishing, to etch holes, cavities and chaimels. HF treatments are preferred tools in microtechnology. 

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