作者：Xiaolu Wang, Xiaoyan Ma* , Duyang Zang
关键字：Aggregation behavior of polystyrene-b-poly(acrylic acid) at the air–water interface
论文来源：期刊
具体来源：Soft Matter, 9, 2013,pp 443-453
发表时间：2013年
The aggregation behavior of amphiphilic
block copolymer polystyrene-b-poly(acrylic acid) (PS-b-PAA) at the air–water
interface was investigated through surface pressure measurements (isotherms, compression–expansion
hysteresis and compression relaxation experiments), Brewster Angle Microscopy (BAM)
imaging and Atomic Force Microscopy (AFM) imaging. It is found that PS-b-PAA
(Mn=11490 gmol-1,
PAA wt%~62%) forms a stable Langmuir monolayer on the water surface (pH=7) by
usingN,Ndimethylformamide (DMF) as the spreading solvent. The aggregation of
block copolymer is induced by an initial diffusion of DMF into water from the
interface. Upon compression of the film, the pseudoplateau observed in the
Langmuir isotherm corresponds to a“pancake-to-brush”transition with the PAA
chains gradually dissolving in the water subphase and stretching underneath the
PS cores.Based on the isotherms and the BAM images, it is suggested that the
polymer chain dynamics in spreading solutions with different concentrations at the
time of solvent diffusion influence the interfacial behavior of block
copolymers significantly. The Langmuir–Blodgett (LB)films prepared at different
surface pressures from different spreading solution concentrations were scanned
by AFM. A variety of morphologies such as wormlike, porous and reticulate
structures, and dots were observed. The isotherms and AFM images show the
spreading solution concentration and surface pressure dependence of the
aggregation behavior of PS-b-PAA copolymer at the air–water interface.