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wizyta

od 2020-09-20

Dr Sebastian Wołoszczuk  | 2001-10 <> 2009-01

Adiunkt

   tango@amu.edu.pl

  0000-0003-0249-0907     55899186600  

Zainteresowania naukowe:
Badania struktury, dynamiki, przejść fazowych i procesów samoorganizacji w stopach i roztworach kopolimerów blokowych z wykorzystaniem metod symulacji komputerowej.

Publikacje                          Seminaria


7.

Wołoszczuk S., Jurga S., Banaszak M.

Towards entropy-driven interstitial micelles at elevated temperatures from selective A1BA2 triblock solutions We simulate selective A1BA2-A and A1BA2-B triblock solutions (that is, mixtures of the A1BA2 triblock with a solvent of either type A or type B) using a lattice Monte Carlo method. Although the simulated triblock chains are compositionally symmetric in terms of the A to B volume ratio, the A1 block is significantly shorter than the A2 block. For the pure A1BA2 melt the phase behavior is relatively well known, including the existence and stability of the recently discovered interstitial micelles which were found at the very strong segregation limit. In this paper, we investigate the stability of the interstitial micelles as a function of triblock volume fraction in a selective solvent of either type A or type B. The main finding of this paper is that adding a selective solvent of type A shifts the stability of the interstitial micelles into significantly higher temperatures which may provide a pathway towards experimental studies of interstitial micelles in real triblock solutions. We also find that adding selective solvents to the A1BA2 melt gives rise to a variety of nonlamellar nanostructures for temperatures and compositions at which the interstitial micelles are stable.

Physical Review E, 94(2), 022502 (2016)

DOI: 10.1103/PhysRevE.94.022502   (Pobrane:  2020-10-23)


6.

Wołoszczuk S., Banaszak M., Knychała P., Lewandowski K., Radosz M.

Alternating multiblock copolymers exhibiting protein-like transitions in selective solvents: A Monte Carlo study We present a lattice Monte Carlo study of a series of block copolymer chains in selective solvents of varying quality, first using a diblock chain of the length of N = 32 with a 16-16 microarchitecture, and then - two multiblock chains of N = 64 and N = 128, with (8-8)(4) and (16-16)(4) microarchitectures, respectively. We report a variety of thermodynamic and structural properties, such as energy, specific heat, end-to-end distance and radius of gyration both for the whole chain and for individual blocks. The simulations have demonstrated that a multiblock copolymer in a selective solvent exhibits protein-like behavior undergoing a two-step transition, first from a swollen state to a secondary 'pearl-necklace' state and then to a tertiary super-globular state as the solvent quality decreases, i.e. upon cooling. We have found that mean-squared end-to-end distances of multiblock chains decrease as the temperature is reduced, as expected.
(C) 2008 Elsevier B.V. All rights reserved.

Journal of Non-Crystalline Solids, 354(35-39), 4138-4142 (2008)

DOI: 10.1016/j.jnoncrysol.2008.06.022   (Pobrane:  2020-10-21)


5.

Wołoszczuk S., Banaszak M., Knychała P., Radosz M.

Monte Carlo phase diagram of symmetric diblock copolymer in selective solvent With a lattice Monte Carlo method, we investigate 16-16 symmetric diblock in selective solvent, A-b-B/A, at 10 volume fractions from 1.0 to 0.1, and for each volume fraction, we perform simulations at up to 54 temperatures, using simulation boxes of different sizes. We report temperature dependencies for a number of quantities such as energy, specific heat, and mean-squared end-to-end distances and construct a phase diagram using the thermodynamic and structural quantities as well as snapshots of the selected configurations. The simulated phase diagram is compared with the experimental data of Lodge and co-workers for nearly symmetric poly(styrene-b-isoprene) mixed with dimethyl phthalate.

Macromolecules, 41(15), 5945-5951 (2008)

DOI: 10.1021/ma0718346   (Pobrane:  2020-10-23)


4.

Wołoszczuk S., Banaszak M., Jurga S., Pakuła T., Radosz M.

Low-temperature ordering effects in diblock copolymer melts from lattice simulation A lattice simulation of a model diblock copolymer melt is presented. In a series of simulation experiments an 8-8 diblock melt is quenched from an athermal state to 47 lower temperatures. A set of simulation boxes, 30x32x30, 40x32x60, 50x32x30, and 60x32x30, is used in order to explore the size effects. Energy, specific heat, copolymer end-to-end distance, lamellar spacing, and the degree of interfacial ordering are reported. For all sizes considered, the low-temperature interfacial ordering is noticeable.
(C) 2004 American Institute of Physics.

Journal of Chemical Physics, 121(23), 12044-12049 (2004)

DOI: 10.1063/1.1812751   (Pobrane:  2020-10-21)


3.

Wołoszczuk S., Banaszak M., Jurga S., Radosz M.

Low-temperature extra ordering effects in symmetric block copolymers from lattice monte carlo simulation Lattice computer simulations of block copolymer melts are reported. Low-temperature lamellar ordering conjecture is presented and its justification is provided. In addition to reviewing the previous data we present a new evidence for the extra ordering effects by recording the mean squared rotational angles as a function of the reduced temperature.

Computational Methods in Science and Technology, 10(2), 219-228 (2004)

DOI: 10.1292/cmst.2004.10.02.219-228
WWW: http://cmst.eu/wp-content/uploads/files/10.12921_cmst.2004.10.02.219-228_Woloszczuk.pdf


2.

Banaszak M., Wołoszczuk S., Jurga S., Pakuła T.

Lamellar ordering in computer-simulated block-copolymer melts by a variety of thermal treatments A lattice computer simulation of a symmetric A-B-A triblock copolymer melt is reported. This melt is quenched, in simulation, from an athermal state to 39 different temperatures using cooperative motion algorithm. Energy, specific heat, copolymer end-to-end distance, bridging fraction, lamellar spacing, concentration profiles, and microstructure visualizations are reported. The quenching simulation results are compared with those obtained by alternative thermal treatments, that is by slow heating and slow cooling. Quenches yield data consistent with theory and experiment, whereas slow cooling and slow heating results do not capture the expected behavior for the lamellar spacing and the bridging fraction. Finally, at very low temperatures, below the conventional order-disorder transition temperature, an additional ordering is recorded, from a conventional lamellar phase to a lamellar structure showing copolymer junction points condensed into a two-dimensional plane.
(C) 2003 American Institute of Physics.

Journal of Chemical Physics, 119(21), 11451-11457 (2003)

DOI: 10.1063/1.1622375   (Pobrane:  2020-10-21)


1.

Banaszak M., Wołoszczuk S., Pakuła T., Jurga S.

Computer simulation of structure and microphase separation in model A-B-A triblock copolymers A set of computer simulations for three symmetric A-B-A triblock copolymer microarchitectures at varying temperatures is reported. By using the cooperative motion algorithm we obtain energy, specific heat, end-to-end distance, and bridging fraction as a function of the reduced temperature. The order-disorder transition temperatures are determined, an outline of a symmetric A-B-A triblock copolymer phase diagram is presented, and the visualization of different microstructures is given. A bicontinuous microstructure is reported at 67% fraction of A component.

Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 66(3), 031804 (2002)

DOI: 10.1103/PhysRevE.66.031804


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