Open AccessFormation of a single poly(N,N-diethylacrylamide) micro-droplet in water by coupling of photothermal effects and an optical force
Author(s) -
Mitsuhiro Matsumoto,
TakaAki Asoh,
Shōji Tanaka,
Takashi Nishiyama,
Hideo Horibe,
Yukiteru Katsumoto,
Yasuyuki Tsuboi
Publication year - 2019
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/1220/1/012034
Subject(s) - lower critical solution temperature , optical tweezers , poly(n isopropylacrylamide) , materials science , polymer , phase (matter) , aqueous solution , micrometer , chemical physics , raman spectroscopy , coupling (piping) , photothermal therapy , nanotechnology , chemistry , copolymer , optics , composite material , organic chemistry , physics
Poly( N -isopropylacrylamide) (PNIPAM) exhibits phase separation with lower critical solution temperature (LCST). In the 1990s, Masuhara and co-workers reported the first demonstration of optical trapping of PNIPAM forming a micrometer-sized polymer droplet. Since then, this technique has attracted much attention to create a molecular assembly in a microspace. In the present study, we targeted poly( N , N -diethylacrylamide) (PDEA), which has an analogous chemical structure to PNIPAM. We demonstrated that optical tweezers formed the unique micro-morphologies of a phase separated PDEA droplet. Fluorescence microscopic images and Raman spectra of the PDEA droplet showed that a lot of smaller-sized water-rich micro-domains were inhomogeneously formed in the droplet. Such unique phase separation behavior was never observed in steady-state heating of an aqueous PDEA solution above its LCST. Our results indicate that a novel micro-structure can be formed by coupling of an optical gradient force and a local temperature elevation.