Synthesis of High χ–Low N Diblock Copolymers by Polymerization‐Induced Self‐Assembly

Abstract

Polymerization-induced self-assembly (PISA) enables the scalable synthesis of functional block copolymer nanoparticles with various morphologies. Herein we exploit this versatile technique to produce so-called "high c-low N" diblock copolymers that undergo nanoscale phase separation in the solid state to produce sub-10 nm surface features. By varying the degree of polymerization of the stabilizer and coreforming blocks, PISA provides rapid access to a wide range of diblock copolymers, and enables fundamental thermodynamic parameters to be determined. In addition, the pre-organization of copolymer chains within sterically-stabilized nanoparticles that occurs during PISA leads to enhanced phase separation relative to that achieved using solution-cast molecularlydissolved copolymer chains. Well-ordered polymeric materials possessing periodic domains with a characteristic length scale of less than 10 nm are attractive scaffolds for a wide range of applications. For example, nanostructured etch masks for lithography provide access to higher domain densities and hence enhanced performance for microchip technology, [1] while microporous polymeric membranes offer considerable potential for water purification via nanofiltration. [2] However, top-down lithographic approaches, such as the use of extremely short ultraviolet wavelengths, become increasingly energy-intensive when targeting sub-20 nm patterns. In principle, block copolymer self-assembly offers a robust route to obtain periodic nanostructures with appropriate mechanical properties and chemical functionalities, which can serve as templates for patterned or nanoporous materials using a bottom-up approach. [3] Clearly, shorter diblock copolymer chains are required to produce smaller domains but it is well-known that

Hydrolysis-Induced Self-Assembly of High-χ–Low-N Bottlebrush Copolymers

“…After the PSM blocks were converted into PGM blocks, a decrease in the solubility triggered the formation of multimolecular micelles with uniform sizes, as evidenced by the increasing D (Figures S2.3.3–S2.3.5) and the micelles observed in the spin-coated films (Figures S2.3.7–S2.3.8), similar to previous studies . It has been reported that for high-χ linear BCPs, micellization in selective solvents can aid in producing long-range-ordered morphologies in the solid state after solvent evaporation . However, for high-χ BBCPs, even with micellization in solution, we found it more difficult to achieve well-ordered morphologies in the solid state after solvent evaporation, which we attribute to a reduced mobility of BBCPs in comparison to linear BCPs.…”

“…70 It has been reported that for high-χ linear BCPs, micellization in selective solvents can aid in producing long-range-ordered morphologies in the solid state after solvent evaporation. 55 However, for high-χ BBCPs, even with micellization in solution, we found it more difficult to achieve well-ordered morphologies in the solid state after solvent evaporation, which we attribute to a reduced mobility of BBCPs in comparison to linear BCPs.…”

“…Consequently, the effect of a very high χ on the self-assembly of bottlebrush copolymers is not well-understood. Even though high-χ bottlebrush copolymers are well-known for their rapid self-assembly, it is reasonable to suspect that a very high χ will impact the molecular dynamics and may negatively impact the rapid self-assembly, as observed in linear high-χ BCPs . Understanding the self-assembly of bottlebrush copolymers with both low and high χ will provide guidance for designing these molecules for future applications.…”

Principles and Characteristics of Polymerization-Induced Self-Assembly with Various Polymerization Techniques

“…Another post-PISA method utilizes the advantages of RAFT-PISA (i.e., efficient polymer synthesis) for the subsequent preparation of various bulk morphologies. 169 These bulk morphologies are obtained directly from post-PISA polymer isolation. Finally, the preparation of composite nanomaterials also introduces interesting new possibilities.…”

Engineering block copolymer materials for patterning ultra-low dimensions

“…Recently, Armes and co-workers described a robust methodology that may prove useful for future sub-10 nm scaling research. 148 The authors reported the benefits of using polymerization induced self-assembly (PISA) 149 for the preparation of high χ-low N BCPs. The nanoparticle formed by the BCPs chains during the PISA process allow a preorganization at the molecular scale leading to rapid self-assembly unlike molecularly dissolved polymer chains.…”