TY - JOUR A1 - Yadavalli, Nataraja Sekhar A1 - Linde, Felix A1 - Kopyshev, Alexey A1 - Santer, Svetlana T1 - Soft matter beats hard matter - rupturing of thin metallic films induced by mass transport in photosensitive polymer films JF - ACS applied materials & interfaces N2 - The interface between thin films of metal and polymer materials play a significant role in modern flexible microelectronics viz., metal contacts on polymer substrates, printed electronics and prosthetic devices. The major emphasis in metal polymer interface is on studying how the externally applied stress in the polymer substrate leads to the deformation and cracks in metal film and vice versa. Usually, the deformation process involves strains varying over large lateral dimensions because of excessive stress at local imperfections. Here we show that the seemingly random phenomena at macroscopic scales can be rendered rather controllable at submicrometer length scales. Recently, we have created a metal polymer interface system with strains varying over periods of several hundred nanometers. This was achieved by exploiting the formation of surface relief grating (SRG) within the azobenzene containing photosensitive polymer film upon irradiation with light interference pattern. Up to a thickness of 60 nm, the adsorbed metal film adapts neatly to the forming relief, until it ultimately ruptures into an array of stripes by formation of highly regular and uniform cracks along the maxima and minima of the polymer topography. This surprising phenomenon has far-reaching implications. This is the first time a direct probe is available to estimate the forces emerging in SRG formation in glassy polymers. Furthermore, crack formation in thin metal films can be studied literally in slow motion, which could lead to substantial improvements in the design process of flexible electronics. Finally, cracks are produced uniformly and at high density, contrary to common sense. This could offer new strategies for precise nanofabrication procedures mechanical in character. KW - metal/polymer interface KW - rupturing of metal film KW - forces generated during surface relief grating formation KW - in situ atomic force microscopy KW - azobenzene KW - two beam interferometry Y1 - 2013 U6 - https://doi.org/10.1021/am4006132w SN - 1944-8244 VL - 5 IS - 16 SP - 7743 EP - 7747 PB - American Chemical Society CY - Washington ER - 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 - Kopyshev, Alexey A1 - Galvin, Casey J. A1 - Genzer, Jan A1 - Lomadze, Nino A1 - Santer, Svetlana T1 - Polymer brushes modified by photosensitive azobenzene containing polyamines JF - Polymer : the international journal for the science and technology of polymers N2 - This paper describes a strategy for preparing photosensitive polymeric grafts on flat solid surfaces by loading diblock-copolymer or homopolymer brushes with cationic azobenzene-containing surfactants. In contrast to previous work, we utilize photosensitive surfactants that bear positively-charged polyamine head groups whose charge varies between 1(+) and 3(+). Poly(methylmethacrylate-b-methacrylic acid) (PMMA-b-PMAA) brushes were prepared by employing atom transfer radical polymerization, where the bottom poly(methyl methacrylate) block was grown first followed by the synthesis of t-butyl methacrylate block that after de-protection yielded poly(methacrylic acid). We used PMMA-b-PMAA brushes with constant grafting density and length of the PMMA block, and three different lengths of the PMAA block. The azobenzene-based surfactants attached only to the PMAA block. The degree of binding (i.e., the number of surfactant molecules per binding site on the brush backbone) of the surfactants to the brush depends strongly on the valence of the surfactant head-group; within the brushes the concentration of the surfactant carrying unit charge is larger than that of multivalent surfactants. We detect pronounced response of the brush topography on irradiation with UV interference pattern even at very low degree of binding (as small as 0.08) of multi-valence surfactant. Areas on the sample that receive the highest UV dose exhibit chain scission. By removing the ruptured chains from the substrate via good solvent, one uncovers a surface topographical relief grating, whose spatial arrangement follows the intensity distribution of the UV light on the sample during irradiation. Due to strong coupling of the multi-valence surfactants to the polymer brush, it was possible in some cases to completely remove the polyelectrolyte block from the PMMA layer. The application of multi-valence azobenzene surfactants for triggering brush photosensitive has important advantage over usage of surfactant with unit charge because relative to single-valence surfactants much lower concentrations of the multivalent surfactant are needed to achieve comparable response upon UV irradiation. (C) 2016 Elsevier Ltd. All rights reserved. KW - Photosensitive brushes KW - Photosensitive azobenzene containing polyamines Y1 - 2016 U6 - https://doi.org/10.1016/j.polymer.2016.03.050 SN - 0032-3861 SN - 1873-2291 VL - 98 SP - 421 EP - 428 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Schimka, Selina A1 - Lomadze, Nino A1 - Rabe, Maren A1 - Kopyshev, Alexey A1 - Lehmann, Maren A1 - von Klitzing, Regine A1 - Rumyantsev, Artem M. A1 - Kramarenko, Elena Yu. A1 - Santer, Svetlana T1 - Photosensitive microgels containing azobenzene surfactants of different charges JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - We report on light sensitive microgel particles that can change their volume reversibly in response to illumination with light of different wavelengths. To make the anionic microgels photosensitive we add surfactants with a positively charged polyamine head group and an azobenzene containing tail. Upon illumination, azobenzene undergoes a reversible photo-isomerization reaction from a trans- to a cis-state accompanied by a change in the hydrophobicity of the surfactant. Depending on the isomerization state, the surfactant molecules are either accommodated within the microgel (trans- state) resulting in its shrinkage or desorbed back into water (cis-isomer) letting the microgel swell. We have studied three surfactants differing in the number of amino groups, so that the number of charges of the surfactant head varies between 1 and 3. We have found experimentally and theoretically that the surfactant concentration needed for microgel compaction increases with decreasing number of charges of the head group. Utilization of polyamine azobenzene containing surfactants for the light triggered remote control of the microgel size opens up a possibility for applications of light responsive microgels as drug carriers in biology and medicine. Y1 - 2016 U6 - https://doi.org/10.1039/c6cp04555c SN - 1463-9076 SN - 1463-9084 VL - 19 SP - 108 EP - 117 PB - Royal Society of Chemistry CY - Cambridge ER - TY - GEN A1 - Schimka, Selina A1 - Lomadze, Nino A1 - Rabe, Maren A1 - Kopyshev, Alexey A1 - Lehmann, Maren A1 - von Klitzing, Regine A1 - Rumyantsev, Artem M. A1 - Kramarenko, Elena Yu. A1 - Santer, Svetlana T1 - Photosensitive microgels containing azobenzene surfactants of different charges T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - We report on light sensitive microgel particles that can change their volume reversibly in response to illumination with light of different wavelengths. To make the anionic microgels photosensitive we add surfactants with a positively charged polyamine head group and an azobenzene containing tail. Upon illumination, azobenzene undergoes a reversible photo-isomerization reaction from a trans- to a cis-state accompanied by a change in the hydrophobicity of the surfactant. Depending on the isomerization state, the surfactant molecules are either accommodated within the microgel (trans-state) resulting in its shrinkage or desorbed back into water (cis-isomer) letting the microgel swell. We have studied three surfactants differing in the number of amino groups, so that the number of charges of the surfactant head varies between 1 and 3. We have found experimentally and theoretically that the surfactant concentration needed for microgel compaction increases with decreasing number of charges of the head group. Utilization of polyamine azobenzene containing surfactants for the light triggered remote control of the microgel size opens up a possibility for applications of light responsive microgels as drug carriers in biology and medicine. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 461 KW - ph-responsive microgels KW - co-monomer content KW - drug-delivery KW - photoresponsive surfactants KW - metal nanoparticles KW - swelling behavior KW - temperature KW - particles KW - collapse KW - hydrogels Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-413528 SN - 1866-8372 IS - 461 ER - TY - JOUR A1 - Schuh, Christian A1 - Lomadze, Nino A1 - Rühe, Jürgen A1 - Kopyshev, Alexey A1 - Santer, Svetlana T1 - Photomechanical degrafting of Azo-functionalized Poly(methacrylic acid) (PMAA) brushes JF - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry N2 - We report on the preparation and characterization of photosensitive polymer brushes. The brushes are synthesized through polymer analogous attachment of azobenzene groups to surface-attached poly(methacrylic acid) (PMAA) chains. The topography of the photosensitive brushes shows a strong reaction upon irradiation with UV light. While homogeneous illumination leaves the polymer topography unchanged, irradiation of the samples with interference patterns with periodically varying light intensity leads to the formation of surface relief gratings (SRG). The height of the stripes of the grating can be controlled by adjusting the irradiation time. The SRG pattern can be erased through solvent treatment when the periodicity of the stripe pattern is less than the length of the fully stretched polymer chains. In the opposite case, photomechanical scission of receding polymer chains is observed during SRG formation, and the inscribed patterns are permanent. Y1 - 2011 U6 - https://doi.org/10.1021/jp2041229 SN - 1520-6106 VL - 115 IS - 35 SP - 10431 EP - 10438 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Kopyshev, Alexey A1 - Galvin, Casey J. A1 - Genzer, Jan A1 - Lomadze, Nino A1 - Santer, Svetlana T1 - Opto-mechanical scission of polymer chains in photosensitive diblock-copolymer brushes JF - Langmuir N2 - In this paper we report on an opto-mechanical scission of polymer chains within photosensitive diblock-copolymer brushes grafted to flat solid substrates. We employ surface-initiated polymerization of methylmethacrylate (MMA) and t-butyl methacrylate (tBMA) to grow diblock-copolymer brushes of poly(methylmethacrylate-b-t-butyl methacrylate) following the atom transfer polymerization (ATRP) scheme. After the synthesis, deprotection of the PtBMA block yields poly(methacrylic acid) (PMAA). To render PMMA-b-PMAA copolymers photosensitive, cationic azobenzene containing surfactants are attached to the negatively charged outer PMAA block. During irradiation with an ultraviolet (UV) interference pattern, the extent of photoisomerization of the azobenzene groups varies spatially and results in a topography change of the brush, i.e., formation of surface relief gratings (SRG). The SRG formation is accompanied by local rupturing of the polymer chains in areas from which the polymer material recedes. This opto-mechanically induced scission of the polymer chains takes place at the interfaces of the two blocks and depends strongly on the UV irradiation intensity. Our results indicate that this process may be explained by employing classical continuum fracture mechanics, which might be important for tailoring the phenomenon for applying it to poststructuring of polymer brushes. Y1 - 2013 U6 - https://doi.org/10.1021/la403241t SN - 0743-7463 VL - 29 IS - 45 SP - 13967 EP - 13974 PB - American Chemical Society CY - Washington ER - TY - CHAP A1 - Schuh, Christian A1 - Prucker, Oswald A1 - Lomadze, Nino A1 - Kopyshev, Alexey A1 - Santer, Svetlana A1 - Ruehe, Juergen T1 - Nanogradient polymer brushes T2 - Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS Y1 - 2012 SN - 0065-7727 VL - 243 PB - American Chemical Society CY - Washington ER - TY - GEN A1 - Schué, Emmanuelle A1 - Kopyshev, Alexey A1 - Lutz, Jean-François A1 - Börner, Hans G. T1 - Molecular bottle brushes with positioned selenols BT - Extending the toolbox of oxidative single polymer chain folding with conformation analysis by atomic force microscopy T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - A synthesis route to controlled and dynamic single polymer chain folding is reported. Sequence-controlled macromolecules containing precisely located selenol moieties within a polymer chain are synthesized. Oxidation of selenol functionalities lead to diselenide bridges and induces controlled intramolecular crosslinking to generate single chain collapse. The cyclization process is successfully characterized by SEC as well as by H-1 NMR and 2D HSQC NMR spectroscopies. In order to gain insight on the molecular level to reveal the degree of structural control, the folded polymers are transformed into folded molecular brushes that are known to be visualizable as single molecule structures by AFM. The "grafting onto" approach is performed by using triazolinedione-diene reaction to graft the side chain polymers. A series of folded molecular brushes as well as the corresponding linear controls are synthesized. AFM visualization is proving the cyclization of the folded backbone by showing globular objects, where non-folded brushes show typical worm-like structures. (C) 2019 The Authors. Journal of Polymer Science published by Wiley Periodicals, Inc. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1397 KW - atomic force microscopy (AFM) KW - diselenide KW - grafted polymers KW - molecular bottle brushes KW - sequence-controlled polymers KW - single chain folding Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-516184 SN - 1866-8372 IS - 1 SP - 154 EP - 162 ER - TY - JOUR A1 - Schué, Emmanuelle A1 - Kopyshev, Alexey A1 - Lutz, Jean-François A1 - Börner, Hans G. T1 - Molecular bottle brushes with positioned selenols BT - Extending the toolbox of oxidative single polymer chain folding with conformation analysis by atomic force microscopy JF - Journal of Polymer Science N2 - A synthesis route to controlled and dynamic single polymer chain folding is reported. Sequence-controlled macromolecules containing precisely located selenol moieties within a polymer chain are synthesized. Oxidation of selenol functionalities lead to diselenide bridges and induces controlled intramolecular crosslinking to generate single chain collapse. The cyclization process is successfully characterized by SEC as well as by H-1 NMR and 2D HSQC NMR spectroscopies. In order to gain insight on the molecular level to reveal the degree of structural control, the folded polymers are transformed into folded molecular brushes that are known to be visualizable as single molecule structures by AFM. The "grafting onto" approach is performed by using triazolinedione-diene reaction to graft the side chain polymers. A series of folded molecular brushes as well as the corresponding linear controls are synthesized. AFM visualization is proving the cyclization of the folded backbone by showing globular objects, where non-folded brushes show typical worm-like structures. (C) 2019 The Authors. Journal of Polymer Science published by Wiley Periodicals, Inc. KW - atomic force microscopy (AFM) KW - diselenide KW - grafted polymers KW - molecular bottle brushes KW - sequence-controlled polymers KW - single chain folding Y1 - 2020 U6 - https://doi.org/10.1002/pola.29496 SN - 2642-4169 VL - 58 IS - 1 SP - 154 EP - 162 PB - Wiley CY - Hoboken ER -