Roll-to-Roll Scalable Production of Ordered Microdomains through Nonvolatile Additive Solvent Annealing of Block Copolymers

Abstract

A new method, “nonvolatile solvent vapor annealing” (NVASA), has been developed to anneal block copolymers during film deposition by controlling the solvent drying process. Precise amounts of high boiling point additive added to the polymer solution briefly remain in the polymer film after casting, leaving the film in a swollen state, increasing its chain mobility, and ultimately improving domain order. We demonstrated the effectiveness of NVASA on several block copolymer systems and used in situ grazing incidence small-angle X-ray scattering (GISAXS) to validate the ordering process during the self-assembly. The simplicity and reproducibility of the method is attractive for implementation in large-scale manufacturing processes such as roll-to-roll printing as swell ratio is easily controlled by the amount of additive used and separate annealing steps are not needed. This work potentially introduces a new way to quickly and cost effectively anneal block copolymers.

Large-Grained Cylindrical Block Copolymer Morphologies by One-Step Room-Temperature Casting

“…Analogous to the constant-swelling-ratio SVA study reported by Gu et al, 58 such experiments may, in principle, be performed by exercising precise control over the solvent pressure above the swollen film, 35 or by retention of nonvolatile plasticizer as proposed by Weller and co-workers. 72 ■ CONCLUSIONS Overall, our straightforward, single-step solvent evaporation annealing protocol is a viable alternative to more complex block-copolymer directed self-assembly methods. Due to its simplicity and compatibility with various film-casting techniques, the method is easy to implement in any soft-matter research laboratory, enabling rapid BCP patterning on various substrates without the need for specialized processing instrumentation.…”

“…Analogous to the constant-swelling-ratio SVA study reported by Gu et al, 58 such experiments may, in principle, be performed by exercising precise control over the solvent pressure above the swollen film, 35 or by retention of nonvolatile plasticizer as proposed by Weller and co-workers. 72 …”

“…Casting polymers from solvent mixtures, used to control the evaporation rate of solvent from the drying films, has been recognized as a viable method of improving internal order in these materials, e.g ., casting semiconducting polythiophenes from a mixture of volatile ( e.g ., chloroform, chlorobenzene) and less volatile cosolvent ( e.g ., di- or trichlorobenzene), increases the degree of crystallinity as well as the size of the crystalline domains by extending the nucleation and growth phase. , Mechanistically, binary mixture casting bears resemblance to solvent vapor annealing, taking advantage of retention of nonvolatile solvent what increases chain diffusivity during the film drying. The beneficial role of residual volatile solvent in block copolymer film ordering has been reported by Perego and co-workers who quantitatively described the role of entrapped toluene in the acceleration of domain coarsening kinetics in thermally annealed PS- b -PMMA thin films. , Recently, the direct casting approach utilizing delayed solvent evaporation was employed by Gu and co-workers who successfully used chloronaphthalene and 1-methylnaphthalene mixtures with toluene as a host solvent to produce well-ordered, large-area PS- b -P2VP cylindrical morphologies in a roll-to-roll fabrication process . In the same report, the researchers have utilized a nonvolatile dibutyl phthalate plasticizer for PS- b -PEO ordering.…”

“…68,69 70,71 Recently, the direct casting approach utilizing delayed solvent evaporation was employed by Gu and co-workers who successfully used chloronaphthalene and 1-methylnaphthalene mixtures with toluene as a host solvent to produce wellordered, large-area PS-b-P2VP cylindrical morphologies in a roll-to-roll fabrication process. 72 In the same report, the researchers have utilized a nonvolatile dibutyl phthalate plasticizer for PS-b-PEO ordering. This method proved very effective; however, immersion in an ethanol bath was necessary to rinse the plasticizer at the end of the process.…”

Developing Anisotropy in Self‐Assembled Block Copolymers: Methods, Properties, and Applications

“…[525] The narrow pore size distribution of these BCP-derived membranes provides advantages of high selectivity and high pore densities for enabling a high flux. [526] Therefore, nearly one order of magnitude increase in water permeability can be achieved by using isoporous BCP membranes for ultrafiltration applications compared to commercial membranes with similar pore sizes. [527] For these filtration relevant applications, development of perpendicularly aligned domains throughout the entire film thickness is essential.…”