Surface-induced phase transitions in thin films of dendrimer block copolymers

Bo Lin,Qingying Zhu,Fang Xie,Chen Zheng

doi:10.1515/epoly-2020-0009

Abstract

Abstract The phase morphologies and phase transitions of dendrimer block copolymer thin films confined between two homogeneous, planar hard substrates had been investigated by a three-dimensional real space self-consistent field theory (SCFT). From the perspectives of property and strength of the preferential substrate, when the film system confined within neutral substrates, the thinner film was easier to take the undulated and perpendicular cylinder phases. For the attractive preference of the substrate on block segment A, the polymer films tended to take the surface-wetting structures that was composed by block segment A. On the contrary, for the repulsive preference of the substrate on block segment A, a phase transition of cylinder-lamellae could be observed increasing with the relative surface strength of the preferential substrate.

Highlights

The phase morphologies of dendrimer copolymer thin film had been explored and divided into five primary classes and each class of morphology included several subfields of relative structure [5,6]
A 3D real space self-consistent field theory (SCFT) had been applied to reveal the phase morphologies and phase transitions of AB dendrimer block copolymer films with an asymmetric component fA = 1/3 that were confined between two homogeneous hard substrates
Five main classes of phase structure had been found to be stable for the confined thin films, which included cylinder (C), lamellae (L), sphere (S), perforated lamellae (PL), and hybrid structure (H) that was mixed by two of the pure structures

Summary

Introduction

De nition 1.4]); (vi) thsecaLffeooldnsa,rddrupgadirelcivoenrsyivsetihnigcleosf, agepnaeitrraonfsofepcptioosnitaegegnetnse, rators for th. B. Lin et al.: Surface-induced phase transitions in thin films of dendrimer block copolymers 77 controllable design of dendrimer. Since the appearance of different morphologies under confinement condition was depended on the interaction between the block segment and the substrate (Ʌ), namely surface confinement, it was fascinating for us to adopt a SCFT theoretical method to study the self-assembly of confined DBC thin films with different strength of Ʌ. A SCFT model was used in this work to evaluate the equilibrium phase morphologies with their stability regions, and the phase transition of order-to-order of the DBC thin films by regulating the film thickness, the phase segregation regime, and the property and strength of surface field

Theoretical method

Results and discussion

Neutral preference dependence

Weak preference dependence

Strong preference dependence

Conclusions