Speaker：Prof. Jin Kon Kim，Pohang University of Science and Technology

Title: Functional Nanomaterials based on Block Copolymer Self-Assembly 

Time：December 13, 2019，10：00 

Venue: Lecture Room 324, AISMST (Building #2, KeJiYuan, North Campus)

Faculties and students are warmly welcome.

School of Molecular Science and Engineering

South China Advanced Institute for Soft Matter Science and Technology

December 4, 2019

Abstract:  

Because the microdomains obtained by block copolymer (BCP) self-assembly are mainly decided by the volume fraction of one block, it is very difficult to fabricate highly asymmetric line patterns based on BCP. We obtained highly asymmetric lamellar morphologies by the use of binary blends of block copolymers [polystyrene-b-poly(2-vinyl pyridine) copolymer (PS-b-P2VP) and  PS-b-poly(4-hydroxystyrene) copolymer (PS-b-PHS)] where P2VP and PHS are capable of the hydrogen bonding. We obtained the asymmetric lamellar microdomains having lamellar width ratio of 4:1.1 This ratio was even increased up to 6:1 with increasing the degree of hydrogen bonding. Also, we observed for the first time the cylindrical and double gyroid microdomains in neat linear block copolymers at the symmetric overall volume fraction by using tetrablock copolymers PS-block-polyisoprene-block-PS-block-polyisoprene (S1I1S2I2).2

Also, nanopatterns with multiple shapes and sizes could not easily prepared by BCP self-assembly.  Though various methods have been introduced in the literature to achieve dual nanopatterns for the next-generation nanolithography, all the methods are not useful for making dual-nanopatterns in a large size due to the complicated processes. By synthesizing a novel miktoarm block copolymer capable of cleavage of one block by ultraviolet, we successfully fabricated dual nanopatterns consisting of dots and lines at desired regions on a single substrate.3

A novel self-neutralization concept is introduced by using star-shaped 18 arm poly(methyl methacrylate)-block-PS copolymers ((PMMA-b-PS)18) exhibiting lamellar and PMMA cylindrical nanodomains. When a thin film was spin-coated on a substrate, vertically aligned lamellar and cylindrical nanodomains were obtained without any pre- or post-treatment, although thermal annealing for a short time (less than 30 min) was required to improve the spatial array of vertically aligned nanodomains. Moreover, vertical orientations are observed on versatile substrates, for instance, semiconductor (Si, SiOx), metal (Au), PS or PMMA-brushed substrate, and a flexible polymer sheet of polyethylene naphthalate (PEN).4 

Finally, we fabricated a high-density array of “accordion-like” plasmonic silver nanorods over a large area (~cm2) exhibiting multiple electromagnetic responses in visible and near-infrared (NIR) wavelengths.5 The concept of fabricating sophisticated nanoscale architectures by utilizing block copolymer self-assembly and incorporating plasmonic metals into one nanodomains could be applied to realize large-scale metamaterials working at visible and NIR wavelengths. 

Brief Biography：

Prof. Jin Kon Kim got his Bachelor’s degree from Seoul National University in Chemical Engineering, Seoul, Korea in 1980, and got his Master’s degree from KAIST (Korea Advanced Institute of Science and Technology) in Chemical Engineering, Daejeon, Korea in 1982. He achieved his PhD degree from Polytechnic University in Chemical Engineering, New York, USA in 1990. Prof. Kim is the Namgo Charied Professor of Pohang University of Science and Technology (POSTECH) since 2018, and he is the Director of the Center for Smart Block Copolymer Self-Assembly funded by the National Research Foundation in Korea since 2004. He won the KAIST Alumni Award in 2007 and won the Samsung Polymer Award in 2006. His research interests are phase behavior and phase transition of block copolymers, development of new functional nanomaterials for membranes, and nanocomposites containing polymer blends and organoclays.