Preparation of poly(γ-benzyl-L-glutamate) nanofibers by electrospinning from isotropic and biphasic liquid crystal solutions

Abstract

Liquid crystal polymer (LCP) nanofibers were prepared by electrospinning from isotropic and biphasic poly(c-benzyl-L-glutamate) (PBLG)/dichloromethane-pyridine solutions. The prepared fibers were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, polarized optical microscopy, wide-angle X-ray diffraction and polarized micro-Raman spectroscopy. The as-spun PBLG fiber from the isotropic solutions had an undulating orientation of closed-packed a-helices similar to a serpentine trajectory in their internal structures. The as-spun PBLG fibers from the biphasic solutions that contained the LC phase had uniaxially oriented hexagonal lattices of a-helices along the fiber axis. These results indicated that the orientation of the ordered structure of the electrospun lyotropic LCP fibers can be controlled by the initial microstructure of the spinning solution.

Bending and kinking in helical polymers

“…The buckling mechanism described in MD simulations for single AH filaments can with some modification also be relevant to AH nanofibers. Two types of AH nanofibers should be highlighted : (a) poly(γ‐benzyl‐ l ‐glutamate) (PBLG) nanofibers and (b) nanofibers involving coiled‐coil (CC) structural motif . PBGL is a synthetic polypeptide that adopts a α‐helical conformation in organic solvents.…”

“…PBGL is a synthetic polypeptide that adopts a α‐helical conformation in organic solvents. The PBLG nanofibers with uniaxial orientation along the fiber axis were prepared by electrospinning from the biphasic solution and the filaments were found to be organized into a closed‐packed hexagonal lattice. Alternatively, self‐assembling of PBGL into nanofibers was achieved by thermoreversible gelation .…”

“…The regular helical structures are routinely used as building blocks in molecular self‐assembly of filamentous nanomaterials . The electrospinning is a technique particularly useful in preparation of helical polymer nanofibers with aligned and molecularly oriented morphology …”

Piezoelectric polymer microfiber‐based composite for the flexible ultra‐sensitive pressure sensor

“…However, PVDF‐based sensors and applications usually lose this electromechanical characteristic because of the phase transformation from polar β‐phase to nonpolar α‐ and γ‐phases at elevated temperatures and residual mechanical strain . Class 2 consists of a variety of biopolymers, including poly(γ‐benzyl‐α, l ‐glutamate) (PBLG), in which the asymmetric character of the polymer chain causes axial orientation and generates polarization whenever a shear force breaks the balance between positive‐induced and negative‐induced charges . PBLG is receiving such a high level of interest because of the ability of its macromolecules to exist in well‐defined α‐helical chain conformation in solution as well as in the solid state (such as the fiber form) .…”

“…The stable α‐helical structure in a PBLG solution is formed by intramolecular hydrogen bonds between an amino group (NH) and a carboxyl group (CO) at the fourth next residue (Figure ). Some researchers have attempted to produce polar PBLG materials using a variety of methods, including the use of a strong magnetic field, the end‐grafting method on solid substrates, and electrospinning, and by integration into composite structures . Hwang et al .…”