Polyvinyl Butyral Modified Polyvinylidene Fluoride Breathable–Waterproof Nanofibrous Membranes with Enhanced Mechanical Performance

Abstract

beings. Breathable and waterproof membranes are the core functional layer of the breathable barrier fabrics. [1,2] Generally, the commercial breathable and waterproof membranes are classified roughly into two types: hydro philic thermoplastic polyurethane (TPU) nonporous mem branes and microporous membranes. Hydrophilic TPU membranes can provide good waterproofness due to their nonporous structure, but its poor moisture transmittance (4 kg m −2 d −1 ) made the wearer uncomfortable. [3] Micro porous membranes use a size exclusion theory to prevent large water droplet from penetrating and permit moisture to transport through porous structure at the same time.As one representative of typical microporous membranes, polytetrafluoroethylene superhydrophobic membranes exhibited good water resistance and modest moisture penetrability (6.3 kg m −2 d −1 ) owing to their clearly visible system of holes and interconnected passageways. [4] These two kinds of breathable-waterproof membranes were Electrospun nanofibrous membranes with outstanding mechanical property, breathability, and waterproofness are critical in protective fields; however, great challenges still remain in creating such functional materials. A novel polyvinylidene fluoride (PVdF)/polyvinyl butyral (PVB) breathable-waterproof membrane with robust mechanical performance is fabricated by introducing thermal posttreatment into electrospun membranes. Embedding of PVB enriches the pristine PVdF nanofibrous membranes with bonded network, optimized pore size, and porosity. The composite membranes are endowed with robust tensile stress of 10.5 MPa and good breaking elongation of 64.5%, which are about four times that of the pure nonbonded PVdF membranes. Apart from this, the bonded PVdF/PVB membranes express integrated properties of high water vapor transmittance rate (10.6 kg m −2 d −1 ), modest air permeability (9.8 mm s −1 ), and good waterproofness (58 kPa). Furthermore, the conveni ence and efficient of this fabrication process will allow for largescale production of PVdF/PVB breathable-waterproof nanofibrous membranes with robust mechanical perfor mance and board applications.

Waterproof and Breathable Electrospun Nanofibrous Membranes

“…f) Waterproof and breathable performance of PVDF membranes heated at various temperatures. Reproduced with permission . Copyright 2016, Wiley‐VCH.…”

“…The other efficient and facile strategy to optimize the structure of PVDF membranes is thermal post‐treatment . Based on good thermal stability of PVDF, various thermal post‐treatment methods have been extended to PVDF electrospun membranes, mainly including thermal pressing and thermal baking.…”

“…Despite the fact that thermal pressing is an efficient way to enhance bonded structure and shrink pore size of PVDF membranes, it is high energy consuming and needs high equipment requirements. To offset the problem, Zhang et al . prepared PVDF nanofibers loaded with polyvinyl butyral (PVB) and employed thermal baking to adjust pore structure of membranes (Figure d).…”

Macrocyclic pyridone pentamer‐modified polystyrene nanofiber for selective metal ion removal from aqueous solution

“…The electrospinning technique can conveniently prepare fibrous materials with fine diameters ranging from micrometers to nanometers with a large specific surface, high porosity area, and excellent adsorption capacity . Nanofibers fabricated by electrospinning from various polymers such as cellulose, cellulose acetate, chitosan, polyacrylonitrile, and polyvinyl alcohol were used to adsorb metal ions from aqueous solutions. Chelating groups, such as the hydroxyl, carboxyl, carbonyl, and cyano, were used to functionalize the nanofibers to afford a high adsorption capacity.…”

Advancing the Science and Technology of Electrospinning and Functional Nanofibers

“…Used compounds include thermoplastic polymers, piezoelectric materials, dyes, drugs, polysaccharides, light‐emitting and conductive organics, and so on, each addressing specific requirements for the ultimate nanofibrous material. Examples of enhanced properties include robustness, breathability and waterproofness, obtained by embedding polyvinyl butyral into polyvinylidene fluoride and thermally post‐treating nanofibers; stability in water for thermally treated polyvinyl alcohol incorporating cross‐linking agents, which is then exploited for metal ion uptake, and for ammonia adsorption following decoration with metal–organic frameworks; stability of pure xanthan polysaccharide fibers electrospun using formic acid as solvent; high voltage output (≥3 V) from multi‐layered, piezoelectric webs doped with electron‐ and hole‐transfer compounds; fast response in optical sensors based on light‐emitting nanofibers made of poly(methyl methacrylate) and a methacrylic homopolymer with anthracene moieties; shape‐memory behaviour in mats fabricated by combining electrospinning and sol–gel reactions . In addition, nanoparticles and microparticles can be used to further tune chemico‐physical characteristics in electrospun composites.…”