Rapid Substrate Neutralization via Side-Chain Hydroxylated Copolymers for Efficient Vertical Alignment of Block...

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Chemistry

Background:

• Directed self-assembly (DSA) of block copolymers (BCPs) is key for nanolithography.
• Achieving ordered nanostructures requires precise control of interfacial energy between BCPs and substrates.
• Current methods for substrate modification are often slow and complex.

Purpose of the Study:

• To develop a cost-effective and scalable substrate neutralization strategy for DSA.
• To optimize the wetting behavior of BCP thin films through controlled surface energy.
• To demonstrate the application of this method in fabricating nanostructures for magnetic film applications.

Main Methods:

• Synthesized a random copolymer: polystyrene-r-poly(methyl methacrylate)-r-poly(2-hydroxyethyl methacrylate) (PS-r-PMMA-r-PHEMA).
• Tuned the hydroxyl density and surface energy of the copolymer by adjusting the HEMA feed ratio.
• Investigated the interfacial interactions between the modified substrate and PS-b-PMMA thin films.

Main Results:

• The PS-r-PMMA-r-PHEMA copolymer effectively neutralized substrates, enabling rapid interfacial equilibrium (5 min) via hydrogen bonding with SiO(x).
• This is significantly faster than conventional methods requiring 72 hours.
• Demonstrated successful application in controlling the coercivity of CoFe/SiO(2) films, showcasing nanostructure fabrication potential.

Conclusions:

• A facile and scalable substrate neutralization strategy using a random copolymer was established.
• This method significantly accelerates the achievement of ordered nanostructures for DSA.
• The approach holds strong potential for advancing large-scale nanolithography and related applications.