Melt-Blown Cross-Linked Fibers from Thermally Reversible Diels–Alder Polymer Networks

Abstract

Melt blowing is a process in which liquid polymer is extruded through orifices and then drawn by hot air jets to produce nonwoven fibers with average diameters typically greater than one micron. Melt-blown nonwoven fiber products constitute a significant fraction (i.e., more than 10%) of the $50 billion global nonwovens market. Thermoplastic feedstocks, such as polyethylene, polypropylene, poly­(phenylene sulfide), and poly­(butylene terephthalate), have dominated melt-blown nonwovens because of their combined cost, good chemical resistance, and high-temperature performance. Cross-linked nonwovens from other commodity polymers (e.g., (meth)­acrylates, styrenics, silicones, etc.) could be attractive alternatives; however, no commercial cross-linked nonwovens currently exist. Here, cross-linked fibers were produced via one-step melt blowing of thermoreversible Diels–Alder polymer networks comprised of furan- and maleimide-functional methacrylate-based polymer backbones. These dynamic networks de-cross-link and flow like viscous liquids under melt-blowing conditions and then revert to a network via cooling-induced cross-linking during/after melt blowing. Finally, the resulting cross-linked fibers can be recycled after use because of their reversible dynamic nature, which may help address microfiber waste as a significant source of microplastic pollution.

Meltblown technology for production of polymeric microfibers/nanofibers: A review

“…Montgomery et al [105] has shown that permanent crosslinks can be introduced by ultraviolet (UV) irradiation applied on produced MB fibers made from a linear amorphous polyester having UV-cross-linkable stilbene groups. On the other hand, thermally reversible crosslinked meltblown fibers were recently produced from Diels−Alder polymer networks comprised of methacrylate-based backbones covalently bonded by dynamic furan-maleimide linkages [121] (heat resistance up to ~ 100 o C) or from linear anthracene-functionalized acrylic polymers irradiated with UV light having the heat resistance up to about 180 o C [122]. Produced reversibly cross-linked fibers have an average diameter typical for MB and can be easily reprocessed/recycled into bulk materials.…”

“…Worldwide production grew from about 2.6 million tons in 1996, worth about $10 billion, to around 8.9 million tons in 2014, worth $35.6 billion, and is predicted to reach to 12.4 million tons by 2020 [96]. Meltblown nonwoven represents an important fraction (i.e., more than 10 %) of the $50 billion global nonwovens market [121]. Due to the increasing trend of nonwoven fabric utilization, the introduction of biodegradable, sustainable raw products to create nonwovens remains unchanged.…”

Synergistic reinforcement of a reversible Diels–Alder type network with nanocellulose

“…The dissociation of crosslinks allows the use of reprocessing methods such as extrusion or fused filament fabrication type 3D printing, which are otherwise reserved for thermoplastic materials. 5,6 One widely used thermoreversible crosslink exploits the Diels-Alder (DA) reaction between furan (F) and maleimide (MI). 7 The popularity of the furan/maleimide coupling reaction stems from the relatively low temperature (100-120 1C) of the retro Diels-Alder (rDA) decoupling reaction [8][9][10] and the click-chemistry type nature and high chemoselectivity of the reaction.…”

“…At low temperatures (association temperature range T association B 50-60 1C) the equilibrium is shifted towards the crosslinked state while at elevated temperatures (dissociation temperature range T diss B 100-120 1C) the reverse reaction is dominating, leading to a loss of network integrity. 12 Since 2002, when Wudl et al 8 published their pioneering work using the DA coupling reaction to form reversibly crosslinked networks, various furan-modified molecules, ranging from oligomers 8,9,13 to elastomers [14][15][16][17][18] and other macromolecules 5,[19][20][21] have been coupled with bismaleimides or maleimide functionalized polymers, rendering the DA reaction the (probably) most well studied coupling reaction within CANs.…”

Combined light- and heat-induced shape memory behavior of anthracene-based epoxy elastomers

“…In this approach, heat remains the ultimate stimulus to enable shape fixation and recovery 22 . Another mechanism of light-controlled shape memory effect is based on photochemical reactions, such as reversible photo-crosslinking 23 – 25 . Anthracene molecules exhibit a reversible dimerization reaction enabled by a [4 + 4] cycloaddition when exposed to UV light with wavelengths higher than 300 nm and a scission of the crosslinked dimers when exposed to UV light with wavelengths lower than 300 nm or temperature above 120 °C 26 .…”