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Pulsed lasers make lightweight glasses out of polymers

Microscopically, glasses are solids that look more like liquids—they lack a regular crystalline structure. The liquid character is no accident, since a typical glass is made by cooling a fluid rapidly. If done in the right way, this skips the usual crystallization that occurs at the freezing point of the material, leaving a disordered state. If we want to create a glass with specific properties, we need precise control over the fluid-to-glass transition, but that has proven very difficult to achieve in practice.

To this end, Yunlong Guo et al. have developed a way to produce stable glasses made of polymers. As described in a Nature Materials paper published February 5, the resulting glasses are extremely lightweight, have a higher transitional temperature, and maintain their properties up to a higher temperatures than normal glasses. The researchers made the glasses by deposition rather than cooling, using a technique known as matrix-assisted pulsed laser evaporation, or MAPLE. The result is a glass built up of nanoscale globules, a material with interesting theoretical properties as well as potential applications.

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New, recyclable plastic lets you weld pieces together with a hairdryer

Organic polymers can be used to create materials with very distinct properties (both good and bad). For example, thermoset materials resist heat and solvents, making them extremely durable and allowing them to be used in the oven. The downside is that, once they're made, that's it—no recycling. Thermoplastics are stable below a set temperature, but they can be melted, allowing them to be remade into new materials. Unfortunately, they don't hold up very well to solvents.

Now, researchers are saying they've created a third option, one that acts like a thermoplastic at high temperatures but can hold up to most solvents. The material's secret? An embedded catalyst that allows chemical bonds to constantly rearrange. The material's desired properties can be tuned based on the polymer it's made from and how much catalyst remains.

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