Solvent and concentration effects on the properties of electrospun poly(ethylene terephthalate) nanofiber mats

Abstract

This study describes the preparation and characterization of nanofibrous mats obtained by electrospinning poly(ethylene terephthalate) (PET) solutions in trifluoroacetic acid/dichloromethane (TFA/DCM). Special attention was paid to the effect of polymer concentration and solvent properties on the morphology, structure, and mechanical and thermal properties of the electrospun nonwovens. The results show that the spinnable concentration of PET solution in TFA/DCM solvents is above 10 wt %. Mats have nanofibrous morphology with fibers having an average diameter in the range of 200–700 nm (depending on polymer concentration and solvent composition) and an interconnected pore structure. Higher solution concentration favors the formation of uniform fibers without beads and with higher diameter. Morphology and fiber assembly changed with the solvent properties. Solvent mixtures rich in TFA, i.e., those with higher dielectric constant and lower surface tension, originated fibers with small diameter. However, due to the lower volatility, those solvent mixtures also produced more branched and crosslinking fibers, with less morphologic uniformity. Mechanical properties (Young's modulus, ultimate strength, and elongation at break) and thermal properties (glass transition, crystallization, and melting) have been studied for the PET electrospun nanomats and compared with those of the original polymer. Solvent effect on fiber crystallinity was not significant, but a complex effect was observed on the mechanical properties of the electrospun mats, as a consequence of the different structural organization of the fibers within the mat network. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 460–471, 2008

Catalytic activity of trypsin entrapped in electrospun poly(ϵ-caprolactone) nanofibers

“…PCL electrospun fibrous membranes (EFM) loaded with trypsin (tryp-EFM) were obtained by water/oil emulsion-electrospinning, conducted on a lab-made electrospinning apparatus using a horizontal set up [24]. The oil phase consisted of a PCL solution in chloroform (CF)/dimethylformamide (DMF) and the water phase contained the enzyme in a phosphate buffer (pH 7.1) containing 0.02 g mL −1 benzamidine, using Span 80 as an emulsifier.…”

“…EFMs porosity defined as the void volume relative to the total volume of the membrane was determined gravimetrically as previously described [24], taking the bulk density of PCL as 1.145 g/cm 3 . EFM thickness was measured at 5 different locations using a digital micrometer (model MDC-25S, Mitutoya Corp., Tokyo, Japan).…”

Fundamental study of crystallization, orientation, and electrical conductivity of electrospun PET/carbon nanotube nanofibers

“…14 They also showed that in the composition of the solvents mix, TFA/DCM volume ratio could be an important determining factor on the final morphology and properties of nanofibers. 14 In one of the earliest works available, polybutylene terephthalate (PBT), a polyester similar to PET and CNT were combined and electrospun to fibers. 25 A suspension of 5 wt % MWCNT dispersed in a solution of PBT/hexafluoro isopropanol (HIFP) produced fibers with an improved thermal stability and better mechanical properties.…”

“…6 Several researchers investigated the structures, properties and applications of polyethylene terephtalate (PET) electrospun nanofibers with and without CNT. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] Considering the unique properties of PET, various applications of PET nanofibers have been developed. [9][10][11]13,15,16,[18][19][20][21][22][23] These include filtration, 9,16,19,20 phase change materials (PCM), 10,13 charge storage, 11 and biomedical applications.…”

Effect of organic solvents in morphology and mechanical properties of electrospun polyvinylpyrrolidone fibers

“…Iwamoto, S. et al [11] used an atomic force microscope (AFM) to determine the elastic modulus of cellulose fibers, but a relation to the solvent was not established. Only Veleirinho, B. et al [12], in their work with solutions with polyethylene terephthalate (PET) and trifluoroacetic acid (TFA)/dichloromethane (DCM) state that the characteristics of the solvent influence mechanical properties of the nanofibrous mats. The elastic modulus, tensile strength, and elongation of the bulk material were measured for different configurations of TFA/DCM tested, concluding that the fibers with the largest modulus were the ones that used 70% TFA, while the ones with 40-50% TFA were the smallest.…”