Morphology of Molecular Assembly

Amphiphilic peptides have a hydrophilic head group and a hydrophobic alkyl tail. The hydrophobic tail helps in aligning the head group to form various secondary, supersecondary, and tertiary conformations. Very thin cylindrical nanofibers (<10-nm diameter) with high aspect ratio, or nano belts, are achieved by a self-assembly of peptide amphiphiles (PAs) under specific solution conditions (pH, ionic strength, and temperature). The 1D nanostructures can interact further among one another, making a 3D network. These 3D network structures make a hydrogel in water. Hydrophobic and electrostatic interactions are the dominating forces in the self-assembly of amphiphilic peptides. The amphiphilic cyclic peptide composed of two b-glucosamino acids and one trans-2-aminocyclohexylcarboxylic acid in formic acid and water (7/3 v/v) makes self-assembled rods and fibers of different dimensions depending upon the solution concentration. A concentration of 1.1 10 5 M provided a rod-shaped assembly of c. 5-nm diameter, which corresponds to a nine-columnar (3 triple bundle) structure (Fig. 4.7A). By increasing the peptide concentration to 1.1 10 4 M, a uniform fibrous assembly of c. 15 nm in

Nano-microfiber Composites For Filtration

Nanofibers prepared by molecular self-assembly are in general not self-supporting and therefore require stabilizing scaffold structures. In fact, a lot of research in the past has been done with su pramolecular self-assembly of molecules forming a network of nanofibers used as organo/hydro gelators. But efforts to use them as a self-standing membrane or as free fibers were not strong. Therefore, the self-assembly of trisamides was also tried on a substrate, i.e., other microfiber non wovens, leading to microenanofiber composites (Fig. 4.4) used for filtration (Weiss et al., 2016).