Glass Futures, 2005

I consider the following areas and issues to be the principal direction of future glass developments.

Information, where glass is used as an information carrier (fibres and screens), and when we consider the dream of the information media wall, glass is the essential support. So far, liquid crystal technology has not been able to overcome its characteristic low-brightness and limited angle of view. Apart from miniaturised lasers, other likely developments may include miniaturised diode arrays and thin film deposits. For example, low-cost thin carbon film, combining the electrical conductance of crystalline graphite with the electron release characteristic of diamond, may enable high brightness, sharpness and wide angle view imaging to be created by the controlled illumination of phosphor coatings (cf. TV screen) with thin wall glass construction.

Colour creation, not in the sense of creating coloured glasses or dichroic film deposit glass, but by utilising micro-encapsulation, either as coatings or as part of the interlayer sandwich in laminated glass. Micro-encapsulation is a process in which tiny particles or droplets are surrounded by a coating to give small capsules with many useful properties. ‘Small is better’ would be an appropriate motto for the many people studying microencapsulation. In its simplest form, a microcapsule is a small sphere with a uniform wall around it. The material inside the microcapsule is referred to as the core, internal phase, or fill, whereas the wall is sometimes called a shell, coating, or membrane. Most microcapsules have diameters between a few micrometers and a few millimeters.Many microcapsules however bear little resemblance to these simple spheres. The core may be a crystal, a jagged adsorbent particle, an emulsion, a suspension of solids, or a suspension of smaller microcapsules.The applications of microencapsulation are numerous. The ones mentioned below are some of the most common today, and others will be developed.²

carbonless copy paper
visual indicators
flavours and essences
pesticides and herbicides
pharmaceuticals
adhesives

This brings me back to the environmentally responsive wall I mentioned earlier. A building’s enclosure could have an improved dielectric performance as well as incorporate variable light transmission and would be an example of an active multi-functional glass façade. PRIVA-LITE®, developed by St Gobain in the late 80’s varies (two levels only) the light transmission. The polymer and the liquid crystals of PRIVA-LITE® are encapsulated in the LC film, and both faces of the film are covered with a transparent, electrical conductive coating, which connect the glazing to the power supply.

2 Super-strength glass. It sounds counterintuitive — a flammable gas stored in glass? — but this is no ordinary glass. Each microsphere is smaller than a grain of table salt, and that’s exactly what makes it so strong. “Glass normally breaks due to the presence of very small flaws in the surface,” says Shelby. Glass bottles and windows break because they are larger than the flaws, which are about one micrometer long. But since the wall thickness of the spheres is less than that, Shelby notes, “no such flaws can exist in the microspheres.” “The strength is about 100 times greater than that of normal glass” and even stronger than the optical fibers used in telecommunications, Shelby adds. “You can crush them if you pound on them with a hammer with them lying on a steel plate, but that’s about it.” At 50 micrometers in diameter and with a wall that’s less than a micrometer thick, each microsphere contains a minute amount of hydrogen. But trillions can be bunched together to make for a sizeable storage system that weighs much less than a traditional heavy steel tank. (Jim Shelby, project leader and professor of ceramic engineering at Alfred University in Alfred, N.Y.)

© Ian Ritchie 2005