DOI： 10.1021/acsami.2c15786

DOI： 10.1021/acsami.1c09233

Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acsanm.1c00366

DOI： 10.1021/acs.macromol.0c02345

DOI： 10.1021/acs.macromol.0c00464

Publishing type：Research paper (scientific journal)  

Very-thick, concentrated brushes of poly(methyl methacrylate) (PMMA) were synthesized by surface-initiated atom transfer radical polymerization in N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, an ionic liquid (IL) solvent. Notably, the high polymerization rate in this IL produced 700 nm-thick PMMA brushes, while the grafting density was observed to increase with increasing feed concentration of a deactivator catalyst (Cu(II)Cl2/ligand), suggesting that grafting density is significantly determined by chain growth during a single activation cycle. A concentrated PMMA brush, with a number-average molecular weight of 1.28 × 106, a polydispersity index of 1.23, a brush-layer thickness of 510 nm, and a grafting density of 0.30 chains nm-2, was successfully synthesized by taking advantage of the IL effect that provides a higher propagation rate constant and a lower termination rate constant. Further increases in the brush-layer thickness were achieved by moderately pressurizing the polymerization medium (i.e., by the combined use of the IL solvent and pressure), and an approximately 1 μm-thick concentrated polymer brush was conveniently synthesized at 50 MPa.

DOI： 10.1021/acs.macromol.0c00161

DOI： 10.1021/acs.macromol.0c00161

Publishing type：Research paper (scientific journal)  

Very-thick, concentrated brushes of poly(methyl methacrylate) (PMMA) were synthesized by surface-initiated atom transfer radical polymerization in N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, an ionic liquid (IL) solvent. Notably, the high polymerization rate in this IL produced 700 nm-thick PMMA brushes, while the grafting density was observed to increase with increasing feed concentration of a deactivator catalyst (Cu(II)Cl-2/ligand), suggesting that grafting density is significantly determined by chain growth during a single activation cycle. A concentrated PMMA brush, with a number-average molecular weight of 1.28 x 10(6), a polydispersity index of 1.23, a brush-layer thickness of 510 nm, and a grafting density of 0.30 chains nm(-2), was successfully synthesized by taking advantage of the IL effect that provides a higher propagation rate constant and a lower termination rate constant. Further increases in the brush-layer thickness were achieved by moderately pressurizing the polymerization medium (i.e., by the combined use of the IL solvent and pressure), and an approximately 1 mu m-thick concentrated polymer brush was conveniently synthesized at 50 MPa.

DOI： 10.1021/acs.macromol.0c00161

DOI： 10.1016/j.triboint.2019.106130

DOI： 10.1021/acsapm.9b00839

Publishing type：Research paper (scientific journal)  

The synthesis of ultrathick concentrated poly(methyl methacrylate) (PMMA) brushes by atom transfer radical polymerization (ATRP) was investigated. The reactions were performed with a catalyst system of Cu(I)Br/dinonyl-2,2′-bipyridine (dN-bipy) and Cu(II)Br /dN-bipy at 60 °C under a high pressure of 500 MPa. The equilibrium constant for this catalyst system was determined to be 1.5 × 10 , which followed the kinetics study and indicated good polymerization rate control. Under the high pressure of 500 MPa, a micrometer scale thick PMMA brush was obtained. During chain growth under the high pressure, the concentration of the deactivator catalyst was demonstrated to significantly affect the graft density of PMMA brushes, which was correlated to the number of monomers added in activation-deactivation cycles. A novel "cutoff" experiment and gel permeation chromatography demonstrated similar propagation for free polymers and graft polymers even under high pressure. 2 -6

DOI： 10.1021/acs.macromol.9b02072

DOI： 10.1021/acs.macromol.9b02072

Publishing type：Research paper (scientific journal)  

The synthesis of ultrathick concentrated poly(methyl methacrylate) (PMMA) brushes by atom transfer radical polymerization (ATRP) was investigated. The reactions were performed with a catalyst system of Cu(I)Br/dinonyl-2,2'-bipyridine (dN-bipy) and Cu(II)Br-2/dN-bipy at 60 degrees C under a high pressure of 500 MPa. The equilibrium constant for this catalyst system was determined to be 1.5 x 10(-6), which followed the kinetics study and indicated good polymerization rate control. Under the high pressure of 500 MPa, a micrometer scale thick PMMA brush was obtained. During chain growth under the high pressure, the concentration of the deactivator catalyst was demonstrated to significantly affect the graft density of PMMA brushes, which was correlated to the number of monomers added in activation-deactivation cycles. A novel "cutoff" experiment and gel permeation chromatography demonstrated similar propagation for free polymers and graft polymers even under high pressure.

DOI： 10.1021/acs.macromol.9b02072

Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acs.langmuir.9b02573

DOI： 10.1021/acs.langmuir.9b01747

DOI： 10.1063/1.5091845

DOI： 10.1021/acs.macromol.9b00720

Publishing type：Research paper (scientific journal)  

A novel surface modification method was developed using a polymer brush and a semi-interpenetrating polymer network (semi-IPN). First, a temperature-responsive copolymer brush of methoxydiethyleneglycol methacrylate and 2-hydroxyethyl methacrylate (P(MDM-co-HEMA)) was constructed on a substrate by surface-initiated atom transfer radical polymerization. The HEMA residues in the grafted chains of the brushes were cross-linked by hexamethylenediisocyanate. Then, functional polymers-zwitterionic, cationic, and anionic polymers used in this study as a model case-were synthesized in the presence of the cross-linked polymer brush-modified substrate, which resulted in the semi-IPN. The thin gel layer having functional polymers as a component of the semi-IPN imparted high elasticity (15-25 MPa) as compared to simple polymer brushes (1 MPa) and specific abilities derived from the semi-IPN polymer. In particular, the adsorption and adhesion of proteins and cells, respectively, to the surface of the thin gel layer incorporating the zwitterionic polymer were drastically suppressed. In contrast, proteins and cells significantly adsorbed and adhered to semi-IPN layers having cationic and anionic polymers. Furthermore, the thin gel layer had switching function because P(MDM-co-HEMA) having lower critical solution temperature was used as the brush component. When the surface density of the brushes was decreased (0.03 chains nm(-2)), the thin gel layer surface interpenetrated with a zwitterionic polymer clearly demonstrated the switching of cell adhesion according to the temperature: cells were detached from the surface when the temperature was changed from 37 to 15 degrees C. High elasticity, specific function derived from the interpenetrating polymer, durability, and thermo-responsiveness of the thin gel layer would be applicable in biomedical and environmental fields.

DOI： 10.1039/c8tb03228a

DOI： 10.1039/c9py00436j

Publishing type：Research paper (scientific journal)  

DOI： 10.1002/chem.201805121

Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acs.langmuir.8b03891