50th Anniversary Perspective: Advanced Polymer Fibers: High Performance and Ultrafine

Abstract

As Macromolecules celebrates its 50 th anniversary, we reflect on the impact of polymer chemistry and engineering on the advancement of synthetic polymer fibers. In this Perspective, we focus on two exemplary cases: i) high performance fibers and ii) ultrafine electrospun fibers. High performance in this context refers to fibers like Kevlar ® and Spectra ® , which emerged as a consequence of novel chemistry and processing innovations to convert synthetic polymers into fibers with exceptional specific stiffness and strength. More recently, the development of "ultrafine" (i.e. submicron diameter) fibers by technologies such as electrospinning has advanced dramatically, resulting in interesting, emergent structures and properties, such as surface and internal morphologies, electrical and mechanical properties, and growth applications like tissue engineering and sensors, which are subjects of current research. In both cases, challenges and

In Situ Complex with by‐product HCl and Release Chloride Ions to Dissolve Aramid

“…In order to dissolve aramid, it is generally necessary to add chloride salts such as CaCl 2 or LiCl in NMP or DMAc . Due to the difference in electronegativity, Ca 2+ or Li + ions can coordinate with oxygen atoms on carbonyl bonds of NMP or DMAc and form cationic complex, followed by releasing Cl − ions .…”

“…In order to dissolve aramid, it is generally necessary to add chloride salts such as CaCl 2 or LiCl in NMP or DMAc . Due to the difference in electronegativity, Ca 2+ or Li + ions can coordinate with oxygen atoms on carbonyl bonds of NMP or DMAc and form cationic complex, followed by releasing Cl − ions . When protons of secondary amide bonds of aramid are present, Cl − ions will form hydrogen‐bond with them and break intermolecular hydrogen‐bond interaction of aramid simultaneously …”

“…[4] Due to the difference in electronegativity, Ca 2 + or Li + ions can coordinate with oxygen atoms on carbonyl bonds of NMP or DMAc and form cationic complex, followed by releasing Cl À ions. [4][5] When protons of secondary amide bonds of aramid are present, Cl À ions will form hydrogen-bond with them and break intermolecular hydrogen-bond interaction of aramid simultaneously. [4] No matter DMAc/LiCl or NMP/CaCl 2 used to synthesize aramid, dissolution power mainly comes from Cl À ions which are offered by chloride salts.…”

“…[4][5] When protons of secondary amide bonds of aramid are present, Cl À ions will form hydrogen-bond with them and break intermolecular hydrogen-bond interaction of aramid simultaneously. [4] No matter DMAc/LiCl or NMP/CaCl 2 used to synthesize aramid, dissolution power mainly comes from Cl À ions which are offered by chloride salts. For polymerization of aramid, HCl is the by-product.…”

Improving Compressive Strength of Aramid Fiber by Introducing Carbon Nanotube Derivates Grafted with Oligomers of Different Conformations and Controlling Its Alignment

“…Poly( p ‐phenylene terephthalamide) (PPTA) fiber, which is usually known for its trade name Kevlar, is a typical high‐performance fiber developed by DuPont in the 1970s. Excellent mechanical properties and heat resistance make it be widely used in structure materials . However, intermolecular interaction of Kevlar is comparatively weak, which brings about low compressive strength (≈300 MPa) and affects its application as strengthen materials …”