Facile Strategy for Room Temperature Knitting of Sulfur in Polybenzoxazine: A New Class of Solution Processable Copolymers

Abstract

Industrial applications of the upcoming class of high-performance biobased polybenzoxazines are currently impeded by the requirement of high polymerization temperatures. Valorization of elemental sulfur (S8), petroleum waste, has provided attractive technological opportunities. However, achieving sulfur copolymers at a low temperature remains a challenging task. Here, a unique facile synthetic strategy was adopted to form a fully sustainable solution-processable benzoxazine-sulfur copolymer via a ring-opening polymerization reaction of isoeugenol-furfurylamine (IE-fa, sourced from naturally abundant biobased feedstocks) and S8 at room temperature. The IE-fa benzoxazine monomer was synthesized under neat conditions and reacted with varying percentages of S8 as sodium polysulfide (Na2S x ) at unprecedented low temperatures (25 and 50 °C) under catalyst-free conditions. The covalent fixation of sulfur (90 wt %), via inverse vulcanization, within ring-opened benzoxazine resulted in an amorphous copolymer as supported by various techniques. The formation of S-rich and Bz-rich domains in the copolymers is governed by the feed-in ratio of monomers and reaction temperature. Copolymers exhibited high glass transition temperatures (10–86 °C) due to the synergistic effects induced by H-bonded ring-opened benzoxazine structures. The present work demonstrates the first example of benzoxazine as a comonomer to form low-temperature solution-processable benzoxazine sulfur benign random copolymers with mid-wave infrared transparency and may advance benzoxazine chemistry toward transparent optics.

Green and sustainable natural derived polysulfides for a broad range of applications

“…17c). 200 The obtained polysulfides showed good solubility in common organic solvents such as CHCl 3 , DMSO, o -DCB, THF, and toluene; however, at higher sulfur content (>90% S) and higher temperature, some insoluble material appeared, indicating some degree of crosslinking. Indeed, increasing the sulfur content and temperature increased the T g of the polysulfides from 10 to 86 °C (Fig.…”

Detoxification of bisphenol A via sulfur-mediated carbon–carbon σ-bond scission

“…[13][14][15][16][17][18] Fully-sustainable sulfur composites can be prepared when petroleum-derived olens are replaced with biologically-produced monomers, such as fatty acids, [19][20][21] triglycerides, [22][23][24][25][26] terpenoids, 25,[27][28][29][30] amino acid derivatives, 31 lignin derivatives, [32][33][34][35] cellulose derivatives, 30,36 and even raw lignocellulosic biomass. 37,38 Reaction temperatures for preparing or shaping HSMs can be lowered by using catalysts, 39 mechanochemical methods, 40 ternary mixtures, 41 pre-formation of more reactive sulfur species, 42 using nucleophiles to fuse materials together through S-S metathesis, 43 or by compression-molding of materials. 44 Promising photochemical routes to C-S bond formation towards preparing or healing HSMs also hold potential for lowering the energy requirements of these processes.…”

Biobased Inverse Vulcanized Polymer from Magnolol as a Multifunctional Ingredient for Carbon-Black-Reinforced Rubber Composites

“…Inverse vulcanization reported by Pyun and coworkers is a facile and powerful methodology to convert the abundant byproduct sulfur from petroleum industry into sulfur-rich polymers. − In addition to petrobased feedstocks, biobased monomers have also been utilized to prepare inverse vulcanized polymers. − Owing to the unique chemophysical properties arising from the high sulfur content, these materials show great potential for various applications, including the refractive index, Li–S battery cathodes, , self-healing materials, , heavy metal capture, , infrared imaging, and also injecting new vitality into rubber composites. Guo et al reported that the sulfur and styrene copolymers through inverse vulcanization as an efficient vulcanizing agent could cross-link diene rubbers in a green manner .…”