Mechanically Robust and Recyclable Cross-Linked Fibers from Melt Blown Anthracene-Functionalized Commodity Polymers.

Melt blowing combines extrusion of a polymer melt through orifices and attenuation of the extrudate with hot high-velocity air jets to produce nonwoven fibers in a single step. Due to its simplicity and high-throughput nature, melt blowing produces more than 10% of global nonwovens (∼$50 billion market). Semicrystalline thermoplastic feedstock, such as poly(butylene terephthalate), polyethylene, and polypropylene, have dominated the melt blowing industry because of their facile melt processability and thermal/chemical resistance; other amorphous commodity thermoplastics (e.g., styrenics, (meth)acrylates, etc.) are generally not employed because they lack one or both characteristics. Cross-linking commodity polymers could enable them to serve more demanding applications, but cross-linking is not compatible with melt processing, and it must be implemented after fiber formation. Here, cross-linked fibers were fabricated by melt blowing linear anthracene-functionalized acrylic polymers into fibers, which were subsequently cross-linked via anthracene-dimerization triggered by either UV light or sunlight. The resulting fibers possessed nearly 100% gel content because of highly efficient anthracene photodimerization in the solid state. Compared to the linear precursors, the anthracene-dimer cross-linked acrylic fibers exhibited enhanced thermomechanical properties suggesting higher upper service temperatures (∼180 °C), showing promise for replacing traditional thermoplastic-based melt blown nonwovens in certain applications. Additionally, given the dynamic nature of the anthracene-dimer cross-links at elevated temperatures (> ∼180 °C), the resulting cross-linked fibers could be effectively recycled after use, providing new avenues toward sustainable nonwoven products.