TY  - JOUR
A1  - Simonova, Maria
A1  - Ivanov, Ivan
A1  - Meleshko, Tamara
A1  - Kopyshev, Alexey
A1  - Santer, Svetlana
A1  - Yakimansky, Alexander
A1  - Filippov, Alexander
T1  - Self-assembly of molecular brushes with polyimide backbone and amphiphilic block copolymer side chains in selective solvents
JF  - Polymers
N2  - Three-component molecular brushes with a polyimide backbone and amphiphilic block copolymer side chains with different contents of the "inner" hydrophilic (poly(methacrylic acid)) and "outer" hydrophobic (poly(methyl methacrylate)) blocks were synthesized and characterized by molecular hydrodynamics and optics methods in solutions of chloroform, dimethylformamide, tetrahydrofuran and ethanol. The peculiarity of the studied polymers is the amphiphilic structure of the grafted chains. The molar masses of the molecular brushes were determined by static and dynamic light scattering in chloroform in which polymers form molecularly disperse solutions. Spontaneous self-assembly of macromolecules was detected in dimethylformamide, tetrahydrofuran and ethanol. The aggregates size depended on the thermodynamic quality of the solvent as well as on the macromolecular architectural parameters. In dimethylformamide and tetrahydrofuran, the distribution of hydrodynamic radii of aggregates was bimodal, while in ethanol, it was unimodal. Moreover, in ethanol, an increase in the poly(methyl methacrylate) content caused a decrease in the hydrodynamic radius of aggregates. A significant difference in the nature of the blocks included in the brushes determines the selectivity of the used solvents, since their thermodynamic quality with respect to the blocks is different. The macromolecules of the studied graft copolymers tend to self-organization in selective solvents with formation of a core-shell structure with an insoluble solvophobic core surrounded by the solvophilic shell of side chains.
KW  - molecular brushes
KW  - amphiphilic side chains
KW  - molecular hydrodynamics and
KW  - optics
KW  - conformational and hydrodynamic characteristics
KW  - aggregation
Y1  - 2020
U6  - https://doi.org/10.3390/polym12122922
SN  - 2073-4360
VL  - 12
IS  - 12
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Vadilonga, Simone
A1  - Zizak, Ivo
A1  - Roshchupkin, Dmitry
A1  - Evgenii, Emelin
A1  - Petsiuk, Andrei
A1  - Leitenberger, Wolfram
A1  - Erko, Alexei
T1  - Observation of sagittal X-ray diffraction by surface acoustic waves in Bragg geometry
JF  - Journal of applied crystallography
N2  - X-ray Bragg diffraction in sagittal geometry on a Y-cut langasite crystal (La3Ga5SiO14) modulated by Lambda = 3 mu m Rayleigh surface acoustic waves was studied at the BESSY II synchrotron radiation facility. Owing to the crystal lattice modulation by the surface acoustic wave diffraction, satellites appear. Their intensity and angular separation depend on the amplitude and wavelength of the ultrasonic superlattice. Experimental results are compared with the corresponding theoretical model that exploits the kinematical diffraction theory. This experiment shows that the propagation of the surface acoustic waves creates a dynamical diffraction grating on the crystal surface, and this can be used for space-time modulation of an X-ray beam.
KW  - surface acoustic waves
KW  - optics
KW  - synchrotron radiation
KW  - sagittal X-ray diffraction
Y1  - 2017
U6  - https://doi.org/10.1107/S1600576717002977
SN  - 1600-5767
VL  - 50
SP  - 525
EP  - 530
PB  - International Union of Crystallography
CY  - Chester
ER  -