Synthesis And Self-Assembly Of Amphiphilic Comb-Copolymers Possessing Polyethyleneimine And Its Derivatives: Site-Selective Formation Of Loop-Cluster Covered Vesicles And Flower Micelles

Amphiphilic block copolymers have attracted a considerable amount of attention in the past two decades because of their ability to self-organize into various complex nanostructures. Most of these studies concentrated on linear amphiphilic block copolymers. In this work, we focused our attention on two type unique comb-like copolymers which grafting amphiphilic diblocked side chains onto main chain of polystyrenic backbone. One is Type-I in which a block of hydrophilic polymers is located inside near to the backbone while other block of hydrophobic poly (phenyl-2-oxazoline) [PPOZ] is in outside far away the backbone. The other one is Type-O in which the hydrophobic block of PPOZ is grafted (inside) onto the main chain backbone then the hydrophilic block is joined (outside) on the PPOZ. A series of five kinds of Type-I and five kinds of Type-O comb-like block copolymers with different components of the amphiphiles were prepared. We performed self-assembly of them in a DMF/water or methanol/water (v/v, 1/9) media. All of Type-O comb-like block copolymers formed micelle. In contrast, in the case of Type-I, interestingly, the comb-like block copolymers possessing hydrophilic blocks with crystalline feature formed loop-cluster covered vesicles, while the others having non-crystalline hydrophilic blocks formed flower-like micelle. We proposed the self-organizing mechanism of these two types comb-like block copolymers and provides new molecular design strategy for the site-selective fabrication of vesicle/micelle possessing special surface structures.