Fiber network formation

Figure 58. Freeze—fracture electron micrograph of compound 13 in (a) dichloromethane and (b) pyridine showing fiber network formation with helical textures.382 Scale bar represents 100 nm. (Reprinted with permission from ref 382. Copyright 2000 Wiley-VCH.)...

Li JL, Liu XY Microengineering of soft functional materials by controlling the fiber network formation. JPhys ChemB. 113(47) (2009) 15467-15472. 

According to the 3D nucleation model, we should then have a linear relationship between In(fg) and l/(Afi/kT) (cf Eq. 19) for the nucleation associated with a given / (including crystallographic mismatch nucleation). In Fig. 13, the Unear fits between In(fg) and l/(A/x/fcT) obtained for both systems without and with EVACP indeed verify the nucleation control at the beginning of fiber network formation. 

Supersaturation-driven interfacial structural mismatch is a new effect identified from the previously described model. This effect is directly responsible for the fiber network formation of many organic gels. With increasing supersaturation, the kinetics will be in favor of some random orientations other than the orientation with the optimal structural match between the nucleating phase and the substrate. This implies that the epitaxial relationship will break down at high supersaturations. 

Interestingly, it was proven that the fiber network formation in SMGs is a crystallization process, which consists of the nucleation and growth of fibers. On the basis of this finding, the micro/nano structure of fiber networks in several SMGs and their macroscopic properties were successfully manipulated by tuning... 

Nucleation and Growth Mechanism of Fiber Network Formation... 

Real time monitoring of the rheological changes has been demonstrated to be a simple and accurate method to follow the kinetics of fiber network formation. The crystallinity can be obtained from the elasticity of the material. According to Einstein s relation, the volume fraction of suspended particles in a system can be correlated to its specific viscosity [16a],... 

As has been discussed, the structure of a fiber network in a material is important since it affects the macroscopic properties of the material. Therefore, understanding the principles of fiber network formation in SMGs is necessary to the development of strategies to control the micro/nanometer structure in order to acquire materials with superior macroscopic properties. 

In the following sections, we will present the fiber network formation through branching at different orientations of fibers, that is, at the growing fiber tips and side surface of fibers. 

Surfactant micelle templated Fiber network formation)... 

The large difference in the polarity of a gelator and a solvent (low solubility of the gelator in the solvent) is essential to the phase separation (crystallization) and fiber network formation in a gel system. Hence, the surfactant molecules present will potentially affect the crystallization of gelators and hence the microstmcture of the fiber networks. 

Figure 2.10 Micrographs illustrating the effects of supersaturation (a—c) and a copolymer (PMMMA) additive (d-f) on fiber network formation, (a-c) GP-1 fiber networks formed in PC at 25, 40, and 50°C, respectively (d-f) GP-1 fiber networks formed in PC at 40 °C with 0.02, 0.04, and 0.06% PMMMA, respectively, (g) fiber length as...

Figure 2.11 Conversion of a multi-domain fiber network to a single fiber network through thermal processing (a,b) and ultrasound-assisted fiber network formation (c,d). (e) Schematic description of the formation of GP-1 spherulites through the normal thermal processing and the formation of an interconnecting fiber network through a seeded process with either thermal or mechanical (i.e., ultrasonic) stimuli. For thermal processing, T,. > > Tj > Tj to ensure the...

---