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Stöbener, Daniel David - One of the best experts on this subject based on the ideXlab platform.

  • Thermoresponsive poly(glycidyl ether) brush coatings on various tissue culture substrates-How Block copolymer design and substrate material govern self-assembly and phase transition
    Basel : MDPI AG, 2020
    Co-Authors: Stöbener, Daniel David, Weinhart Marie
    Abstract:

    Thermoresponsive poly(glycidyl ether) brushes can be grafted to applied tissue culture substrates and used for the fabrication of primary human cell sheets. The self-assembly of such brushes is achieved via the directed physical adsorption and subsequent UV immobilization of Block copolymers equipped with a short, photo-reactive benzophenone-based Anchor Block. Depending on the chemistry and hydrophobicity of the benzophenone Anchor, we demonstrate that such Block copolymers exhibit distinct thermoresponsive properties and aggregation behaviors in water. Independent on the Block copolymer composition, we developed a versatile grafting-to process which allows the fabrication of poly(glycidyl ether) brushes on various tissue culture substrates from dilute aqueous-ethanolic solution. The viability of this process crucially depends on the chemistry and hydrophobicity of, both, benzophenone-based Anchor Block and substrate material. Utilizing these insights, we were able to manufacture thermoresponsive poly(glycidyl ether) brushes on moderately hydrophobic polystyrene and polycarbonate as well as on rather hydrophilic polyethylene terephthalate and tissue culture-treated polystyrene substrates. We further show that the temperature-dependent switchability of the brush coatings is not only dependent on the cloud point temperature of the Block copolymers, but also markedly governed by the hydrophobicity of the surface-bound benzophenone Anchor and the subjacent substrate material. Our findings demonstrate that the design of amphiphilic thermoresponsive Block copolymers is crucial for their phase transition characteristics in solution and on surfaces. © 2020 by the authors

  • Thermoresponsive Poly(glycidyl ether) Brush Coatings on Various Tissue Culture Substrates - How Block Copolymer Design and Substrate Material Govern Self-Assembly and Phase Transition
    2020
    Co-Authors: Stöbener, Daniel David, Weinhart Marie
    Abstract:

    Thermoresponsive poly(glycidyl ether) brushes can be grafted to applied tissue culture substrates and used for the fabrication of primary human cell sheets. The self-assembly of such brushes is achieved via the directed physical adsorption and subsequent UV immobilization of Block copolymers equipped with a short, photo-reactive benzophenone-based Anchor Block. Depending on the chemistry and hydrophobicity of the benzophenone Anchor, we demonstrate that such Block copolymers exhibit distinct thermoresponsive properties and aggregation behaviors in water. Independent on the Block copolymer composition, we developed a versatile grafting-to process which allows the fabrication of poly(glycidyl ether) brushes on various tissue culture substrates from dilute aqueous-ethanolic solution. The viability of this process crucially depends on the chemistry and hydrophobicity of, both, benzophenone-based Anchor Block and substrate material. Utilizing these insights, we were able to manufacture thermoresponsive poly(glycidyl ether) brushes on moderately hydrophobic polystyrene and polycarbonate as well as on rather hydrophilic polyethylene terephthalate and tissue culture-treated polystyrene substrates. We further show that the temperature-dependent switchability of the brush coatings is not only dependent on the cloud point temperature of the Block copolymers, but also markedly governed by the hydrophobicity of the surface-bound benzophenone Anchor and the subjacent substrate material. Our findings demonstrate that the design of amphiphilic thermoresponsive Block copolymers is crucial for their phase transition characteristics in solution and on surfaces

  • Glycidyl Ether-Based Coatings on Polystyrene Culture Substrates for Temperature-Triggered Cell Sheet Fabrication
    2019
    Co-Authors: Stöbener, Daniel David
    Abstract:

    Within this work, thermoresponsive coatings based on poly(glycidyl ether)s (PGEs) were developed for applied polystyrene (PS) tissue culture substrates. Following the “grafting to“ approach, Block copolymers comprising a random, high molecular weight, thermoresponsive Block and a short, hydrophobic benzophenone (BP) Block were synthesized via the sequential, monomer-activated, oxy-anionic ring-opening polymerization (ROP). Ultrathin layers in the sub-nanometer range were immobilized on PS by physical adsorption and UV-induced C, H-insertion of PGE Block copolymers via their photo-reactive BP Anchor Block. The coatings mediated the adhesion of human dermal fibroblasts (HDFs) and allowed the temperature triggered detachment of confluent cell sheets. HDF sheet detachment was found to be induced by the cooperative effects between the partial rehydration of the PGE chains and the cell repellant PS substrate background. In order to improve the performance of PGE monolayers, Block copolymers were subsequently self-assembled on PS substrates from dilute aqueous solution under selective solvent conditions. UV immobilization yielded thermoresponsive polymer brushes, which undergo a “pancake-to-brush” transition upon temperature reduction. The improved structure and thermal response of the brush-like PGE coatings as well as the optimization of cell culture parameters facilitated the fabrication of confluent HDF, human aortic smooth muscle cell (HAoSMC) and human umbilical vein endothelial cell (HUVEC) sheets, which constitute the main building Blocks of blood vessels. To functionalize PS culture substrates via the “grafting from” approach, a solvent-free, microwave-assisted synthesis of well-defined oligo(glycidyl ether)s (OGEs) was developed. Fast reaction rates could be solely attributed to the high reaction temperatures reached during microwave heating and the obtained oligomers exhibited highly molecular weight- and concentration-dependent CPTs in water. Further, end-functional oligo(glycidyl ether) acrylate (OGEA) macromonomers were synthesized by in situ quenching of the oxy-anionic ROP. Subsequently, a photopolymerization process was developed to graft OGEA macromonomers from PS culture substrates. Surfaceinitiated photografting from bulk macromonomer films yielded porous, rigid, gel-like OGEA coatings with unique bottlebrush properties. Bottlebrushes with optimized structure proved to be functional coatings for the fabrication of HDF sheets. The controlled detachment of cell sheets was found to be triggered by the rehydration of OGEA bottlebrush side chains rather than a macroscopic swelling of the gel-like coatings upon temperature reduction. In summary, this work introduces facile methods for the functionalization of applied PS tissue culture surfaces with thermoresponsive, PGE-based coatings and demonstrates their high potential as functional substrates for cell sheet fabrication

Georges Hadziioannou - One of the best experts on this subject based on the ideXlab platform.

  • influence of Anchor Block size on the thickness of adsorbed Block copolymer layers
    Langmuir, 1997
    Co-Authors: G F Belder, Ten G Brinke, Georges Hadziioannou
    Abstract:

    We present surface force data on three different polystyrene/poly(2-vinylpyridine) Block copolymers (PS/P2VP) with a fixed size of the nonadsorbing PS Block but widely varying sizes of the adsorbing P2VP Block. With respect to the sizes of the two Blocks, they range from moderately to highly asymmetric. The equilibrium force profiles are almost overlapping, which means that the variation in layer thickness is very small over a large range of Anchor Block size. This finding is in disagreement with the predictions of simple scaling models for polymer brushes. However it agrees with findings from neutron reflectivity data on a comparable series of PS/P2VP Block copolymers. We also find agreement with recent neutron reflectivity experiments on poly(dimethylsiloxane)/polystyrene and with self-consistent field calculations on selectively adsorbed Block copolymers.

Weinhart Marie - One of the best experts on this subject based on the ideXlab platform.

  • Thermoresponsive Poly(glycidyl ether) Brush Coatings on Various Tissue Culture Substrates - How Block Copolymer Design and Substrate Material Govern Self-Assembly and Phase Transition
    2020
    Co-Authors: Stöbener, Daniel David, Weinhart Marie
    Abstract:

    Thermoresponsive poly(glycidyl ether) brushes can be grafted to applied tissue culture substrates and used for the fabrication of primary human cell sheets. The self-assembly of such brushes is achieved via the directed physical adsorption and subsequent UV immobilization of Block copolymers equipped with a short, photo-reactive benzophenone-based Anchor Block. Depending on the chemistry and hydrophobicity of the benzophenone Anchor, we demonstrate that such Block copolymers exhibit distinct thermoresponsive properties and aggregation behaviors in water. Independent on the Block copolymer composition, we developed a versatile grafting-to process which allows the fabrication of poly(glycidyl ether) brushes on various tissue culture substrates from dilute aqueous-ethanolic solution. The viability of this process crucially depends on the chemistry and hydrophobicity of, both, benzophenone-based Anchor Block and substrate material. Utilizing these insights, we were able to manufacture thermoresponsive poly(glycidyl ether) brushes on moderately hydrophobic polystyrene and polycarbonate as well as on rather hydrophilic polyethylene terephthalate and tissue culture-treated polystyrene substrates. We further show that the temperature-dependent switchability of the brush coatings is not only dependent on the cloud point temperature of the Block copolymers, but also markedly governed by the hydrophobicity of the surface-bound benzophenone Anchor and the subjacent substrate material. Our findings demonstrate that the design of amphiphilic thermoresponsive Block copolymers is crucial for their phase transition characteristics in solution and on surfaces

  • Thermoresponsive poly(glycidyl ether) brush coatings on various tissue culture substrates-How Block copolymer design and substrate material govern self-assembly and phase transition
    Basel : MDPI AG, 2020
    Co-Authors: Stöbener, Daniel David, Weinhart Marie
    Abstract:

    Thermoresponsive poly(glycidyl ether) brushes can be grafted to applied tissue culture substrates and used for the fabrication of primary human cell sheets. The self-assembly of such brushes is achieved via the directed physical adsorption and subsequent UV immobilization of Block copolymers equipped with a short, photo-reactive benzophenone-based Anchor Block. Depending on the chemistry and hydrophobicity of the benzophenone Anchor, we demonstrate that such Block copolymers exhibit distinct thermoresponsive properties and aggregation behaviors in water. Independent on the Block copolymer composition, we developed a versatile grafting-to process which allows the fabrication of poly(glycidyl ether) brushes on various tissue culture substrates from dilute aqueous-ethanolic solution. The viability of this process crucially depends on the chemistry and hydrophobicity of, both, benzophenone-based Anchor Block and substrate material. Utilizing these insights, we were able to manufacture thermoresponsive poly(glycidyl ether) brushes on moderately hydrophobic polystyrene and polycarbonate as well as on rather hydrophilic polyethylene terephthalate and tissue culture-treated polystyrene substrates. We further show that the temperature-dependent switchability of the brush coatings is not only dependent on the cloud point temperature of the Block copolymers, but also markedly governed by the hydrophobicity of the surface-bound benzophenone Anchor and the subjacent substrate material. Our findings demonstrate that the design of amphiphilic thermoresponsive Block copolymers is crucial for their phase transition characteristics in solution and on surfaces. © 2020 by the authors

Xiangzhen Yan - One of the best experts on this subject based on the ideXlab platform.

  • push force analysis of Anchor Block of the oil and gas pipeline in a single slope tunnel based on the energy balance method
    PLOS ONE, 2016
    Co-Authors: Yifei Yan, Lisong Zhang, Xiangzhen Yan
    Abstract:

    In this paper, a single-slope tunnel pipeline was analysed considering the effects of vertical earth pressure, horizontal soil pressure, inner pressure, thermal expansion force and pipeline—soil friction. The concept of stagnation point for the pipeline was proposed. Considering the deformation compatibility condition of the pipeline elbow, the push force of Anchor Blocks of a single-slope tunnel pipeline was derived based on an energy method. Then, the theoretical formula for this force is thus generated. Using the analytical equation, the push force of the Anchor Block of an X80 large-diameter pipeline from the West—East Gas Transmission Project was determined. Meanwhile, to verify the results of the analytical method, and the finite element method, four categories of finite element codes were introduced to calculate the push force, including CAESARII, ANSYS, AutoPIPE and ALGOR. The results show that the analytical results agree well with the numerical results, and the maximum relative error is only 4.1%. Therefore, the results obtained with the analytical method can satisfy engineering requirements.

G F Belder - One of the best experts on this subject based on the ideXlab platform.

  • influence of Anchor Block size on the thickness of adsorbed Block copolymer layers
    Langmuir, 1997
    Co-Authors: G F Belder, Ten G Brinke, Georges Hadziioannou
    Abstract:

    We present surface force data on three different polystyrene/poly(2-vinylpyridine) Block copolymers (PS/P2VP) with a fixed size of the nonadsorbing PS Block but widely varying sizes of the adsorbing P2VP Block. With respect to the sizes of the two Blocks, they range from moderately to highly asymmetric. The equilibrium force profiles are almost overlapping, which means that the variation in layer thickness is very small over a large range of Anchor Block size. This finding is in disagreement with the predictions of simple scaling models for polymer brushes. However it agrees with findings from neutron reflectivity data on a comparable series of PS/P2VP Block copolymers. We also find agreement with recent neutron reflectivity experiments on poly(dimethylsiloxane)/polystyrene and with self-consistent field calculations on selectively adsorbed Block copolymers.