Polystyrene with hydrophobic end groups: synthesis, kinetics, interfacial activity, and self-assemblies templated by breath figures

Abstract

The breath figure method has emerged as a new self-assembly technique to fabricate ordered porous materials, which show potential applications in many fields, such as size-selective separation membranes. However, it is challenging to customize the structures, especially to precisely tune the pore size in a wide range. Moreover, the relationship between polymer structure and film morphologies is still unknown. In this paper, we report a facile, effective, and controllable way to manipulate the evolution of morphologies of honeycomb films, which is based on the blends of an amphiphilic block copolymer and polystyrenes with hydrophobic end groups. A series of atom transfer radical polymerization (ATRP) initiators with alkyl or fluorinated groups were synthesized for polystyrenes with hydrophobic end groups. Polymerization kinetics confirmed the viability of these ATRP initiators. Surface segregation behaviors of the hydrophobic end groups were demonstrated by measuring the surface chemical composition and surface free energies. We found that the polystyrenes with hydrophobic end groups form ordered films only at high polymer concentration (40-60 mg mL À1 ); moreover, the use of blends of two types of polystyrenes, one of which has a hydrophobic end group whereas the other has a hydrophilic block, can greatly increase the regularity of the honeycomb films and provide the possibility to fine-tune the pore diameter. Moreover, the evolution of surface morphologies of the films can be ideally correlated with the surface free energies of the end-functionalized polymers.

Porphyrinated polyimide honeycomb films with high thermal stability for HCl gas sensing

“…It can be seen that both pore diameter and pore center distance decrease gradually with the increase of porphyrin content in the polyimides. This results may support the hypothesis that the porphyrin units are able to interact with and to stabilize water droplets because a series of work [45][46][47][48][49][50] demonstrate that increasing the ability of polymer to stabilize water droplets can lead to not only high regularity but also small pore size for the honeycomb lms. 15 It is worth pointing out that PPI honeycomb lms exhibit multilayer structure whereas the lm prepared from HPI is monolayered (Fig.…”

“…45 For example, polystyrene without any polar end groups is able to form honeycomb lm under certain condition, 46 however, the lm regularity can be signicantly improved when polar blocks or end groups are incorporated into the polymers. [47][48][49] It is generally accepted that the condensed water droplets can be effectively stabilized and prevented from coalescing by the hydrophilic blocks or end groups of polymers in the breath gure process. 25,45,50 In this study, we suggest the porphyrin units are able to interact with the water molecules, which promotes the formation of ordered honeycomb lms.…”

Synthesis of core cross-linked star polystyrene with functional end groups and self-assemblies templated by breath figures

“…The hydrophilic end groups can help to stabilize the condensed water droplets via segregating at the solution/water interface. 62 As polymers with hydrophilic end groups possess strong interfacial activity, 63,64 it is speculated that the sinking process of water droplets may be induced by faster stabilization and elongated solidifying processes. Therefore, the stars with hydrophilic end groups tend to form multilayer structures.…”

Synthesis of diverse α,ω-telechelic polystyrenes with di- and tri-functionality via tandem or one-pot strategies combining aminolysis of RAFT-polystyrene and a thiol–ene “click” reaction

“…Very recently, a variety of a-mono and a,u-telechelic functional polystyrenes [52][53][54] were synthesized via atomic transfer radical polymerization based methodology and employed for fabricating highly ordered honeycomb lms.…”