Organic and Inorganic PCL-Based Electrospun Fibers

Abstract

In this work, different nanocomposite electrospun fiber mats were obtained based on poly(e-caprolactone) (PCL) and reinforced with both organic and inorganic nanoparticles. In particular, on one side, cellulose nanocrystals (CNC) were synthesized and functionalized by “grafting from” reaction, using their superficial OH– group to graft PCL chains. On the other side, commercial chitosan, graphene as organic, while silver, hydroxyapatite, and fumed silica nanoparticles were used as inorganic reinforcements. All the nanoparticles were added at 1 wt% with respect to the PCL polymeric matrix in order to compare the different behavior of the woven no-woven nanocomposite electrospun fibers with a fixed amount of both organic and inorganic nanoparticles. From the thermal point of view, no difference was found between the effect of the addition of organic or inorganic nanoparticles, with no significant variation in the Tg (glass transition temperature), Tm (melting temperature), and the degree of crystallinity, leading in all cases to high crystallinity electrospun mats. From the mechanical point of view, the highest values of Young modulus were obtained when graphene, CNC, and silver nanoparticles were added to the PCL electrospun fibers. Moreover, all the nanoparticles used, both organic and inorganic, increased the flexibility of the electrospun mats, increasing their elongation at break.

Electrospinning of PCL-Based Blends: Processing Optimization for Their Scalable Production

“…The electrospun PCL-based mats were randomly collected in a grounded aluminum foil perpendicular collector; a working distance between the needle and the collector was set at 15 cm on the basis of previous works [ 5 , 16 ]. The polymeric PCL-based solutions were flowed through the inner needle and the same mixture of solvent used for the polymeric solutions (CHCl 3 :DMF in 4:1 proportion) was flowed through the outer needle, to avoid the evaporation of the polymeric solution on the external surface of the spinneret.…”

“…Polymeric electrospun mats are very versatile materials and they can be used for the production of monolayer and multilayer films and/or sandwich type composites [ 6 , 7 , 8 , 9 ]. Moreover, the electrospun mats can be easily modified by reinforcing the fibers with organic [ 10 , 11 ] and inorganic nanofillers [ 12 , 13 , 14 ] and metallic nanoparticles [ 15 , 16 ]. Therefore, the electrospun mats have gained interest in the industrial sector since they can be easily processed as multifunctional materials and can be applied in different industrial fields such as controlled release of drugs [ 13 ], antioxidants [ 10 , 17 ] and/or antimicrobial [ 17 ] agents; in addition they have piezoelectric properties [ 18 ] and shape memory performance [ 19 , 20 ].…”

“…Thus, many strategies have been proposed to improve PCL’s performance in order to extend its industrial applications; proposed improvements include copolymerization [ 21 , 22 , 23 , 24 ], the addition of different modifiers (e.g., fillers, nanofillers, etc.) [ 16 ] and blending with other biopolymers [ 24 , 26 ]. In this context, to guarantee the biocompatible and/or biodegradable character of the final PCL-based material, the polymer or additives added should also be biocompatible and biodegradable.…”

“…However, one of the main disadvantages when working with electrospun fibers is the poor mechanical properties of this material. In order to improve the mechanical performance of electrospun mats, several strategies have been reported, mainly focused on reinforcing biopolymeric matrices with both organic and inorganic nanofillers [ 16 ]. In 2018, Kai et al [ 32 ] added lignin copolymers as a filler of nanofibers and obtained an increase in the tensile strength and elongation at break.…”

“…Considering that to prepare solvent-based electrospun polymeric fibers, polymers should be homogeneously dissolved in a proper solvent [ 31 ], the solvents were selected on the basis of a solubility parameter (δ) similar to that of the polymeric matrix. In particular, the PCL-based polymer solution concentration was set at 10 wt % in a solvent mixture of chloroform and dimethylformamide in 80:20 proportion on the basis of our previous works [ 5 , 16 ]. The PCL-MCC and PCL-PHB formulations were prepared in different proportions by adding 1, 5 and 10 wt % of MCC or PHB with respect to PCL.…”