Dependence of Self-Assembled Peptide Hydrogel Network Structure on Local Fibril Nanostructure

Physically cross-linked, fibrillar hydrogel networks are formed by the self-assembly of β-hairpin peptide molecules with varying degrees of strand asymmetry. The peptide registry in the self-assembled state can be used as a design element to generate fibrils with twisting, nontwisting, or laminated morphology. The mass density of the networks varies significantly, and can be directly related to the local fibrillar morphology as evidenced by small angle neutron scattering (SANS) and in situ substantiation using cryogenic transmission electron microscopy (cryo-TEM) under identical concentrations and conditions. Similarly, the density of the network is dependent on changes in the peptide concentration. Bulk rheological properties of the hydrogels can be correlated to the fibrillar nanostructure, with the stiffer, laminated fibrils forming networks with a higher G′ as compared to the flexible, singular fibrillar networks

A Method for the Quantification of Nanoparticle Dispersion in Nanocomposites Based on Fractal Dimension

Dispersion quantification provides critical insight and towards understanding and improving the influence of nanoparticle dispersion on the behaviour of the nanocomposite at macro and nanoscale level. This study was precipitated by the limitations of most methods for quantifying dispersion to sufficiently handle issues regarding scalability, complexity, consistency and versatility. A quantity (D 0 ) based on the variance of the fractal dimension was used to quantify dispersion successfully. The concept was validated using real microscopy images. The approach is simple and versatile to implement

Anisotropy across length scales: Conformation and self-assembly of coil-liquid diblock coplymers in nematic solvent

Coil-Liq. Cryst. diblock copolymers exhibit ordered morphologies in liq. crystal (LC) solvent that reflect the interplay between microphase segregation of the coil (LC phobic) block and the spontaneous anisotropy in the local chain conformation of the LC block. The self-assembly of "end-on" and "side-on" coil-LC diblock copolymers with near const. side group liq. crystal polymer (SGLCP) block lengths and increasing coil (polystyrene) block lengths (40 kg/mol to 120 kg/mol) was investigated using SANS and TEM. SANS measurements of dil. solns. of these coil-SGLCP diblocks in aligned nematic LC solvent reveal the formation of anisotropic, self-assembled micelles. Unstained and pos.-stained TEM enabled a direct correspondence between the structural features found in the anisotropic scattering and micelle sizes. Size scales of the morphol. features at both at the network (>100 nm) and intrachain (5-100 nm) levels were examd. The shape and anisotropy of the micelle core appears to depend on both the SGLCP block and the polystyrene block lengths

Anisotropy across length scales: Conformation and self-assembly of coil-liquid crystal diblock coplymers in nematic solvent

Coil- Liq. Cryst. diblock copolymers exhibit ordered morphologies in liq. crystal (LC) solvent that reflect the interplay between microphase segregation of the coil (LC phobic) block and the spontaneous anisotropy in the local chain conformation of the LC block. The self- assembly of "end- on" and "side- on" coil- LC diblock copolymers with near const. side group liq. crystal polymer (SGLCP) block lengths and increasing coil (polystyrene) block lengths (40 kg /mol to 120 kg /mol) was investigated using SANS and TEM. SANS measurements of dil. solns. of these coil- SGLCP diblocks in aligned nematic LC solvent reveal the formation of anisotropic, self- assembled micelles. Unstained and pos.- stained TEM enabled a direct correspondence between the structural features found in the anisotropic scattering and micelle sizes. Size scales of the morphol. features at both at the network (>100 nm) and intrachain (5- 100 nm) levels were examd. The shape and anisotropy of the micelle core appears to depend on both the SGLCP block and the polystyrene block lengths