Effect of Nanostructured Domains in Self-Assembled Block Copolymer Films on Sequential Infiltration Synthesis

Abstract

There are broad interests in selective and localized synthesis in nanodomains of self-assembled block copolymers (BCPs) for a variety of applications. Sequential infiltration synthesis (SIS) shows promise to selectively grow a controllable amount of materials in one type of nanodomain of a self-assembled BCP film. However, the effects of nanostructured domains in a BCP film and SIS cycles on the material growth behavior of SIS are rarely studied. In this work, we investigated the growth behavior of TiO SIS within self-assembled polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films and the two corresponding pure homopolymer films (PS and PMMA) by using in situ quartz crystal microbalance (QCM). According to the experimental results, reactant purge steps are essential to enable a high selectivity of SIS in PMMA nanodomains in the BCP films by eliminating the undesired homogeneous reactions. The continuous PS nanodomain acts as the main channel in transporting reactants to PMMA nanodomains in the self-assembled PS-b-PMMA BCP films. The segregated nanoscale PMMA nanodomains in the BCP films show dramatically different TiCl diffusion/reaction behavior than a continuous PMMA film. The mass gain per SIS cycle within PMMA nanodomains decreases quickly with increasing cycle number. After 7 TiO SIS cycles, TiO SIS can only take place at the interface between PS and PMMA nanodomains in the BCP film. The TiO SIS process can uniformly modify PMMA nanodomains throughout a self-assembled PS-b-PMMA film up to the diffusion depth owing to the unique nanostructure-enabled diffusion. SIS cycle number and chemistry of a BCP will strongly affect the material growth behavior of a SIS chemistry on the BCP film and, therefore, the final morphology of the resulting nanomaterial. Detailed studies are warranted for a SIS process on a self-assembled BCP film of different chemistry.

Effect of the Density of Reactive Sites in P(S‐r‐MMA) Film during Al2O3 Growth by Sequential Infiltration Synthesis

“…A progressive scaling of the diffusivity is observed as a function of the size of the diffusing molecules . Recent results about the infiltration in PMMA of TiCl 4 molecules, which has similar size of TMA, report a diffusivity of 0.7 × 10 −12 cm 2 s −1 consistently with this picture . Conversely, ex situ analysis by Leng and Losego provided significantly different diffusion coefficients for TMA molecules in PMMA .…”

Resolving Triblock Terpolymer Morphologies by Vapor-Phase Infiltration

“…[27][28][29][30][31][32][33][34][35][36][37] The infiltration process proceeds via sorption (diffusion) and block-selective reaction of vapor-phase organometallic precursors into the polymer blocks with suitable reactive moieties to generate infused inorganic materials within the target BCP microdomains. [38][39] The hybrid nanocomposite thus formed can also be converted to an inorganic nanostructure inheriting the original structure of the polymer microdomains, 34,36 not only producing various functional nanostructures in a simple process but also enabling all-organic BCP morphologies to be fully resolved. 31 ALD of metal oxide precursors into cylinder-and gyroidforming BCPs has been used to generate 1D and 3D nanostructures for a broad variety of nanotechnologies such as gas sensors, solar cells, photocatalysts, and pattern transfer masks.…”

Water treatment based on atomically engineered materials: Atomic layer deposition and beyond

“…Peng et al also investigated effects of BCP nanodomains on precursor sorption/diffusion behavior and kinetics during SIS (Figure 5D). 81 The precursor TiCl 4 diffuses through PS domains and combines with carbonyl groups and Ti-OH groups in the PMMA domains of BCPs. Then, during the purge stage, excess free TiCl 4 molecules diffuse out of the BCP film again mainly through PS domains.…”