A Sulfur Copolymers (SDIB)/Polybenzoxazines (PBz) Polymer Blend for Electrospinning of Nanofibers

Abstract

This study demonstrated the processability of sulfur copolymers (SDIB) into polymer blend with polybenzoxazines (PBz) and their compatibility with the electrospinning process. Synthesis of SDIB was conducted via inverse vulcanization using elemental sulfur (S8). Polymer blends produced by simply mixing with varying concentration of SDIB (5 and 10 wt%) and fixed concentration of PBz (10 wt%) exhibited homogeneity and a single-phase structure capable of forming nanofibers. Nanofiber mats were characterized to determine the blending effect on the microstructure and final properties. Fiber diameter increased and exhibited non-uniform, broader fiber diameter distribution with increased SDIB. Microstructures of mats based on SEM images showed the occurrence of partial aggregation and conglutination with each fiber. Incorporation of SDIB were confirmed from EDX which was in agreement with the amount of SDIB relative to the sulfur peak in the spectra. Spectroscopy further confirmed that SDIB did not affect the chemistry of PBz but the presence of special interaction benefited miscibility. Two distinct glass transition temperatures of 97 °C and 280 °C indicated that new material was produced from the blend while the water contact angle of the fibers was reduced from 130° to 82° which became quite hydrophilic. Blending of SDIB with component polymer proved that its processability can be further explored for optimal spinnability of nanofibers for desired applications.

Effect on thermal stability of microstructure and morphology of thermally-modified electrospun fibers of polybenzoxazines (PBz) blended with sulfur copolymers (SDIB)

“…PBz (10 wt%) blended with SDIB (10 wt%) was prepared by using mixture of DMSO and THF (1/3) (v/v) based on the procedure described in the works of Parreño et al 25 Electrospun fibers was fabricated using vertically-aligned electrospinning apparatus composed of a 10 ml syringe with needle (ID = 0.8 mm) connected to a syringe pump, a ground electrode, and a high voltage supply (Falco Enterprise Co. Ltd, Taipei, Taiwan). The needle was connected to the high voltage supply, which generates positive DC voltages up to 40 kV.…”

Effect of a direct sulfonation reaction on the functional properties of thermally-crosslinked electrospun polybenzoxazine (PBz) nanofibers

“…20 If the sulfonation reaction was successful in incorporating sulfonate groups on the nanobers' surfaces, then there is an expected change in the hydrophobicity of the ES-PBz nanobers. Non-sulfonated ES-PBz nanobers are hydrophobic with a water contact angle of 130 based on the previous work of Parreño et al 16 The crosslinking that occurred in the PBz nanobers during thermal treatment is known to be an effective method to change the morphology as well as the surface properties of the polymers. 20 However, pure PBz nano-bers retained their hydrophobicity even aer undergoing postelectrospinning thermal treatment.…”

“…12 But, aside from the modication of benzoxazine monomers during the synthetic phase, different strategies of functionalization such as preparation of polymer blends and composites, hybridization with inorganic materials, and chemical incorporation of the benzoxazine structure into the polymer have also been reported. 2 Several works involve the blending of PBz with other polymers such as rubber, 13 polycarbonate (PC), 14 polyurethane (PU), 15 poly(3-caprolactone) (PCL), 14 and poly(S-rdiisopropenylbenzene) (SDIB), 16 which resulted in the modication of the functional properties derived from the synergy of polymer components. In the previous study of Li and Liu, 8 a composite of polybenzoxazine (PBz)-modied polybenzimidazole (PBI) nanobers showed enhancement in the mechanical strength using PBz as the crosslinking agent.…”