scholarly journals Homeostatic growth of dynamic covalent polymer network toward ultrafast direct soft lithography

2021 ◽  
Vol 7 (43) ◽  
Author(s):  
Di Chen ◽  
Chujun Ni ◽  
Lulin Xie ◽  
Ye Li ◽  
Shihong Deng ◽  
...  
Author(s):  
J. A. N. Zasadzinski ◽  
R. K. Prud'homme

The rheological and mechanical properties of crosslinked polymer gels arise from the structure of the gel network. In turn, the structure of the gel network results from: thermodynamically determined interactions between the polymer chain segments, the interactions of the crosslinking metal ion with the polymer, and the deformation history of the network. Interpretations of mechanical and rheological measurements on polymer gels invariably begin with a conceptual model of,the microstructure of the gel network derived from polymer kinetic theory. In the present work, we use freeze-etch replication TEM to image the polymer network morphology of titanium crosslinked hydroxypropyl guars in an attempt to directly relate macroscopic phenomena with network structure.


2000 ◽  
Vol 628 ◽  
Author(s):  
Mark A. Clarner ◽  
Michael J. Lochhead

ABSTRACTOrganically modified silica gels and dye-doped silica gels have been patterned into micrometer-scale structures on a substrate using micro molding in capillaries (MIMIC). This approach is from a class of elastomeric stamping and molding techniques collectively known as soft lithography. Soft lithography and sol-gel processing share attractive features in that they are relatively benign processes performed at ambient conditions, which makes both techniques compatible with a wide variety of organic molecules, molecular assemblies, and biomolecules. The combination of sol-gel and soft lithography, therefore, holds enormous promise as a tool for microfabrication of materials with optical, chemical, or biological functionality that are not readily patterned with conventional methods. This paper describes our investigation of micro-patterned organic-inorganic hybrid materials containing indicator dyes for microfluidic sensor applications. Reversible colorimetric pH sensing via entrapped reagents is demonstrated in a prototype microfluidic sensor element. Patterned structures range from one to tens of micrometers in cross-section and are up to centimeters in length. Fundamental chemical processing issues associated with mold filling, cracking and sensor stability are discussed.


2011 ◽  
Vol 39 (1) ◽  
pp. 44-58 ◽  
Author(s):  
Y. Masumoto ◽  
Y. Iida

Abstract The purpose of this work is to develop a new analytical method for simulating the microscopic mechanical property of the cross-linked polymer system using the coarse-grained molecular dynamics simulation. This new analytical method will be utilized for the molecular designing of the tire rubber compound to improve the tire performances such as rolling resistance and wet traction. First, we evaluate the microscopic dynamic viscoelastic properties of the cross-linked polymer using coarse-grained molecular dynamics simulation. This simulation has been conducted by the coarse-grained molecular dynamics program in the OCTA) (http://octa.jp/). To simplify the problem, we employ the bead-spring model, in which a sequence of beads connected by springs denotes a polymer chain. The linear polymer chains that are cross-linked by the cross-linking agents express the three-dimensional cross-linked polymer network. In order to obtain the microscopic dynamic viscoelastic properties, oscillatory deformation is applied to the simulation cell. By applying the time-temperature reduction law to this simulation result, we can evaluate the dynamic viscoelastic properties in the wide deformational frequency range including the rubbery state. Then, the stress is separated into the nonbonding stress and the bonding stress. We confirm that the contribution of the nonbonding stress is larger at lower temperatures. On the other hand, the contribution of the bonding stress is larger at higher temperatures. Finally, analyzing a change of microscopic structure in dynamic oscillatory deformation, we determine that the temperature/frequency dependence of bond stress response to a dynamic oscillatory deformation depends on the temperature dependence of the average bond length in the equilibrium structure and the temperature/frequency dependence of bond orientation. We show that our simulation is a useful tool for studying the microscopic properties of a cross-linked polymer.


Author(s):  
Д.Л. Байдаков

Методом химического нанесения из растворов халькогенидных стекол в н-бутиламине получены многокомпонентные халькогенидные пленки CuI-As2Se3, CuI-PbI2-As2Se3, CuI-SbI3-As2Se3, CuI-SbI3-PbI2-As2Se3. Синтез многокомпонентных медьсодержащих халькогенидных стекол, использовавшихся для нанесения пленок, проводили методом вакуумной плавки в кварцевых ампулах при температуре 400…950 °С и остаточном давлении не более 0,13 Па. Закалку стекол производили от 600 °С в воду со льдом с разливом расплава в ампуле. Навеску стекла размельчали в порошок и кипятили в н-бутиламине до полного растворения. Для предотвращения процессов окисления, нанесение и отжиг пленок проводили в атмосфере химически инертного азота. Подложку помещали на устройство для вращения, наносили на нее раствор и вращали подложку со скоростью несколько тысяч оборотов в минуту. Отжиг пленок проводили при температуре 100 °С в течение 1 ч. Измерение электропроводности полученных пленок проводили на постоянном и переменном токе в зависимости от значений электропроводности в температурном интервале 20…100 °С. Измерение коэффициентов диффузии проводили абсорбционным методом. Из диффузионных экспериментов определены значения коэффициентов диффузии катионов изотопа 110mAg в медьсодержащих халькогенидных пленках. Установлено, что значения коэффициентов диффузии ионов Ag+ в химически нанесенных пленках и исходных стеклах практически не различаются. Аналогию значений коэффициентов диффузии изотопа 110mAg в халькогенидных стеклах и пленках на их основе можно объяснить сохранением полимерной сетки связей халькогенидных стекол при их растворении в органических основаниях (аминах). В процессе нанесения и формирования пленок полимерная (макромолекулярная) структура раствора халькогенидных стекол сохраняется. The method of chemical deposition from solutions of chalcogenide glasses in n-butyl amine obtained multicomponent chalcogenide films CuI-As2Se3, CuI-PbI2-As2Se3, CuI-SbI3-As2Se3, CuI-SbI3-PbI2-As2Se3. Synthesis of copper multicomponent chalcogenide glasses, used for film deposition was carried out by vacuum melting in quartz ampoule at a temperature of 400…950 °C and a residual pressure of not more than 0.13 Pa. The temperature of glass produced from the 600 °C to the ice water spill of the melt in the ampoule. Weigh glass comminuted to a powder and heated in n-butylamine until complete dissolution. To prevent oxidation, deposition and annealing of the films was carried out in an atmosphere of nitrogen chemically inert. The substrate is placed on a device for rotating, it was applied to the solution and the substrate was rotated at a speed of several thousand revolutions per minute. Annealing of the films was carried out at 100 °C for 1 hour. Measurement of the electrical conductivity of the obtained films was conducted at a constant current and variable depending on the conductivity values ​​in the temperature range from 20 to 100 °C. Measurement of diffusion coefficients was performed according to the absorption method. From diffusion experiments, the values ​​of the diffusion coefficients 110mAg isotope cations in copper chalcogenide films. It was found that the values ​​of the diffusion coefficients of the ions Ag+ in a chemically deposited films and the original glasses are indistinguishable. The analogy of the diffusion coefficient values ​​110mAg isotope in chalcogenide glasses and films based on them can be attributed to the preservation of the polymer network connections chalcogenide glasses when dissolved in organic bases (amines). During application and film formation the polymer (macromolecular) structure of chalcogenide glasses of the solution is maintained.


2012 ◽  
Vol 26 (3) ◽  
pp. 249-255
Author(s):  
Boniek Castillo Dutra Borges ◽  
Fabrício Lopes da Rocha Pereira ◽  
Roberta Caroline Bruschi Alonso ◽  
Rodivan Braz ◽  
Marcos Antônio Japiassú Resende Montes ◽  
...  

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 83
Author(s):  
Ritika Singh Petersen ◽  
Anja Boisen ◽  
Stephan Sylvest Keller

Microparticles are ubiquitous in applications ranging from electronics and drug delivery to cosmetics and food. Conventionally, non-spherical microparticles in various materials with specific shapes, sizes, and physicochemical properties have been fabricated using cleanroom-free lithography techniques such as soft lithography and its high-resolution version particle replication in non-wetting template (PRINT). These methods process the particle material in its liquid/semi-liquid state by deformable molds, limiting the materials from which the particles and the molds can be fabricated. In this study, the microparticle material is exploited as a sheet placed on a deformable substrate, punched by a robust mold. Drawing inspiration from the macro-manufacturing technique of punching metallic sheets, Micromechanical Punching (MMP) is a high-throughput technique for fabrication of non-spherical microparticles. MMP allows production of microparticles from prepatterned, porous, and fibrous films, constituting thermoplastics and thermosetting polymers. As an illustration of application of MMP in drug delivery, flat, microdisk-shaped Furosemide embedded poly(lactic-co-glycolic acid) microparticles are fabricated and Furosemide release is observed. Thus, it is shown in the paper that Micromechanical punching has potential to make micro/nanofabrication more accessible to the research and industrial communities active in applications that require engineered particles.


RSC Advances ◽  
2021 ◽  
Vol 11 (37) ◽  
pp. 22544-22555
Author(s):  
Atefeh Safaei-Yaraziz ◽  
Shiva Akbari-Birgani ◽  
Nasser Nikfarjam

The interlacing of biopolymers and synthetic polymers is a promising strategy to fabricate hydrogel-based tissue scaffolds to biomimic a natural extracellular matrix for cell growth.


Author(s):  
Liang Yao ◽  
Yongpeng Liu ◽  
Han-Hee Cho ◽  
Meng Xia ◽  
Arvindh Sekar ◽  
...  

The development of efficient and stable organic semiconductor-based photoanodes for solar fuel production is advanced by using a robust in situ-formed covalent polymer network together with a mesoporous inorganic film in a hybrid bulk heterojunction.


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