4(%3)3 - Ecole nationale supérieure de chimie de Montpellier

higher pressure end, the flow of the water restricts this concerted movement. It can be said that thisfragmental contact is purely random filling up in nature rather than zipping up of the two oppositefragments as shown by the scarring observed for the healed samples in the SEM images (Figure – 2.22).Figure – 2.26: No self-healing is possible in case of a perforation created by an air bubble or any other objectpresent on the surface during the membrane process.The presence of free dangling chains onto the created fragments is further strengthened by thefact that no stable healing was observed when a perforation was induced intentionally by creating asmall air bubble during the film preparation. Consequently, block copolymer chains arrange themselvesaround bubble’s periphery in such a way that the bridge formation between the two opposite sides of itis avoided. When compression takes place, even though the micelles are pushed towards each other,there are no dangling chains to create a bridge or even even if there are chains to create a bridge, it willnot be stable since the closure will result in the destabilization of the micelles’ equilibrium and create aphysical warp onto its surface. Hence the closure is essentially temporary and once the pressure isrelieved, the micelles are forced to retreat to their original positions to restore the original equilibriumthereby recreating the original space (Figure – 2.26).2.9 CONCLUSION71