How Structure-Related Collapse Mechanisms Determine Nanoscale Inhomogeneities in Thermoresponsive Polymers

2012 ◽  
Vol 45 (18) ◽  
pp. 7535-7548 ◽  
Author(s):  
Dennis Kurzbach ◽  
Martina Schömer ◽  
Valerie S. Wilms ◽  
Holger Frey ◽  
Dariush Hinderberger
Keyword(s):  
Thermoresponsive Polymers ◽  
Collapse Mechanisms

scholarly journals Thermoresponsive Polymers as Macromolecular Coordination Ligands: Complexation-Dependence of Thermally Induced Aggregation in Aqueous Solution

2021 ◽  
Author(s):  
Maximilian Felix Toni Meier ◽  
Franck Thetiot ◽  
Narsimhulu Pittala ◽  
Ingo Lieberwirth ◽  
Cleiton Kunzler ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Thermoresponsive Polymers ◽  
Thermally Induced ◽  
Coordination Sites ◽  
Induced Aggregation

We have designed novel macromolecular coordination ligands (MCLs) by conjugation of thermoresponsive polymers based on poly(N-isopropylacrylamide) (M ̅_n around 3 to 25 kg∙mol-1) with 1,2,4-triazole coordination sites. These triazole units...

scholarly journals Thermal Behaviour of Common Thermoresponsive Polymers in Phosphate Buffer and in Its Salt Solutions

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 90
Author(s):  
Łukasz Otulakowski ◽  
Maciej Kasprów ◽  
Aleksandra Strzelecka ◽  
Andrzej Dworak ◽  
Barbara Trzebicka
Keyword(s):  
Thermal Behaviour ◽  
Phosphate Buffer ◽  
Pure Water ◽  
Thermal Response ◽  
The Body ◽  
Solution Temperature ◽  
Thermoresponsive Polymers ◽  
Aqueous Polymer ◽  
Cloud Point Temperature ◽  
Size Of Particles

Thermoresponsive polymers are a promising material for drug nanocarrier preparation, which makes the study of their aggregation in physiological conditions very important. In this paper, the thermal behaviour of the thermoresponsive polymers poly(N-isopropylacrylamide), poly(2-isopropyl-2-oxazoline-co-2-n-propyl-2-oxazoline) and poly[(2-hydroxyethyl methacrylate)-co-oligo(ethylene glycol) methyl ether methacrylate] were studied in phosphate buffer (PBS) and solutions of its salts in concentration as in PBS. The thermal response of the polymers was measured using UV-Vis and dynamic light scattering (DLS). The salts shifted the cloud point temperature (TCP) of the (co)polymers to higher values compared to the TCP of aqueous polymer solutions. In PBS and NaCl solutions, all polymers exhibited an unexpected and previously unreported transmittance profile. During heating, an additional aggregation of polymers appeared above the TCP accompanied by the formation of a precipitate. In monosodium phosphate solutions and pure water, the studied polymers showed lower critical solution temperature (LCST-type) behaviour. DLS measurements showed that a salt influenced the size of the resulting polymer particles. The sizes and stability of particles depended on the heating rate. In PBS and NaCl solutions, the size of particles in the dispersion decreased above 60 °C, and the precipitate appeared on the bottom of the cuvette. The additional aggregation of polymer and its falling out of solution may hinder the removal of carriers from the body and has to be taken into account when preparing nanocarriers.

scholarly journals Effect of pore diameter on the elution behavior of analytes from thermoresponsive polymer grafted beads packed columns

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kenichi Nagase ◽  
Yuta Umemoto ◽  
Hideko Kanazawa
Keyword(s):  
Pore Diameter ◽  
Packed Column ◽  
Packed Columns ◽  
Butyl Methacrylate ◽  
Thermoresponsive Polymer ◽  
Thermoresponsive Polymers ◽  
Column Temperature ◽  
Pore Sizes ◽  
Temperature Responsive ◽  
Elution Behavior

AbstractTemperature-responsive chromatography using thermoresponsive polymers is innovative and can control analyte retention via column temperature. Analyte elution behavior in this type of chromatography depends on the modified thermoresponsive polymer and the structure of the base materials. In the present study, we examine the effect of the pore diameter of silica beads on analyte elution behavior in temperature-responsive chromatography. Poly(N-isopropylacrylamide-co-n-butyl methacrylate) hydrogel was applied to beads of various pore sizes: 7, 12, and 30 nm. Almost the same amount of copolymer hydrogel was applied to all beads, indicating that the efficiency of copolymer modification was independent of pore size. Analyte retention on prepared beads in a packed column was observed using steroids, benzodiazepines, and barbiturates as analytes. Analyte retention times increased with temperature on packed columns of 12- and 30-nm beads, whereas the column packed with 7-nm beads exhibited decreased retention times with increasing temperature. The difference in analyte elution behavior among the various pore sizes was attributed to analyte diffusion into the bead pores. These results demonstrate that bead pore diameter determines temperature-dependent elution behavior.

scholarly journals Cruciate Ligament Cell Sheets Can Be Rapidly Produced on Thermoresponsive poly(glycidyl ether) Coating and Successfully Used for Colonization of Embroidered Scaffolds

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 877
Author(s):  
Ingrid Zahn ◽  
Daniel David Stöbener ◽  
Marie Weinhart ◽  
Clemens Gögele ◽  
Annette Breier ◽  
...  
Keyword(s):  
Gene Expression ◽  
Type I Collagen ◽  
Cruciate Ligament ◽  
Glycidyl Ether ◽  
Stable Gene ◽  
Type I ◽  
Cell Sheets ◽  
Thermoresponsive Polymers ◽  
Related Phenotype ◽  
Anterior Cruciate

Anterior cruciate ligament (ACL) cell sheets combined with biomechanically competent scaffolds might facilitate ACL tissue engineering. Since thermoresponsive polymers allow a rapid enzyme-free detachment of cell sheets, we evaluated the applicability of a thermoresponsive poly(glycidyl ether) (PGE) coating for cruciate ligamentocyte sheet formation and its influence on ligamentocyte phenotype during sheet-mediated colonization of embroidered scaffolds. Ligamentocytes were seeded on surfaces either coated with PGE or without coating. Detached ligamentocyte sheets were cultured separately or wrapped around an embroidered scaffold made of polylactide acid (PLA) and poly(lactic-co-ε-caprolactone) (P(LA-CL)) threads functionalized by gas-phase fluorination and with collagen foam. Ligamentocyte viability, protein and gene expression were determined in sheets detached from surfaces with or without PGE coating, scaffolds seeded with sheets from PGE-coated plates and the respective monolayers. Stable and vital ligamentocyte sheets could be produced within 24 h with both surfaces, but more rapidly with PGE coating. PGE did not affect ligamentocyte phenotype. Scaffolds could be colonized with sheets associated with high cell survival, stable gene expression of ligament-related type I collagen, decorin, tenascin C and Mohawk after 14 d and extracellular matrix (ECM) deposition. PGE coating facilitates ligamentocyte sheet formation, and sheets colonizing the scaffolds displayed a ligament-related phenotype.

Thermoresponsive polymers based on poly-vinylpyrrolidone: applications in nanoparticle catalysis

2010 ◽  
Vol 46 (10) ◽  
pp. 1631 ◽  
Author(s):  
Ning Yan ◽  
Jiaguang Zhang ◽  
Yuan Yuan ◽  
Guang-Tao Chen ◽  
Paul. J. Dyson ◽  
...  
Keyword(s):  
Thermoresponsive Polymers ◽  
Nanoparticle Catalysis

A study of the collapse of arrays of cavities

1988 ◽  
Vol 190 ◽  
pp. 409-425 ◽  
Author(s):  
J. P. Dear ◽  
J. E. Field
Keyword(s):  
Shock Wave ◽  
High Speed ◽  
High Speed Photography ◽  
Cavitation Damage ◽  
Major Mechanism ◽  
Collapse Mechanisms ◽  
Multiple Jets ◽  
Circular Holes ◽  
Schlieren Photography ◽  
Thick Glass

This paper describes a method for examining the collapse of arrays of cavities using high-speed photography and the results show a variety of different collapse mechanisms. A two-dimensional impact geometry is used to enable processes occurring inside the cavities such as jet motion, as well as the movement of the liquid around the cavities, to be observed. The cavity arrangements are produced by first casting water/gelatine sheets and then forming circular holes, or other desired shapes, in the gelatine layer. The gelatine layer is placed between two thick glass blocks and the array of cavities is then collapsed by a shock wave, visualized using schlieren photography and produced from an impacting projectile. A major advantage of the technique is that cavity size, shape, spacing and number can be accurately controlled. Furthermore, the shape of the shock wave and also its orientation relative to the cavities can be varied. The results are compared with proposed interaction mechanisms for the collapse of pairs of cavities, rows of cavities and clusters of cavities. Shocks of kbar (0.1 GPa) strength produced jets of c. 400 m s−1 velocity in millimetre-sized cavities. In closely-spaced cavities multiple jets were observed. With cavity clusters, the collapse proceeded step by step with pressure waves from one collapsed row then collapsing the next row of cavities. With some geometries this leads to pressure amplification. Jet production by the shock collapse of cavities is suggested as a major mechanism for cavitation damage.

Tuning of Polymeric Nanoparticles by Coassembly of Thermoresponsive Polymers and a Double Hydrophilic Thermoresponsive Block Copolymer

2016 ◽  
Vol 120 (20) ◽  
pp. 4635-4643 ◽  
Author(s):  
Qilu Zhang ◽  
Lenny Voorhaar ◽  
Sergey K. Filippov ◽  
Berin Fatma Yeşil ◽  
Richard Hoogenboom
Keyword(s):  
Block Copolymer ◽  
Polymeric Nanoparticles ◽  
Thermoresponsive Polymers

Behavior Factor of Dual Systems with BRBs and Semi-Rigid Connections

2018 ◽  
Vol 763 ◽  
pp. 949-956 ◽  
Author(s):  
Francesca Barbagallo ◽  
Melina Bosco ◽  
Edoardo Michele Marino ◽  
Pier Paolo Rossi
Keyword(s):  
Nonlinear Dynamic ◽  
Nonlinear Dynamic Analysis ◽  
Design Procedure ◽  
Eurocode 8 ◽  
Deformation Capacity ◽  
Structural System ◽  
Dual Systems ◽  
Behavior Factor ◽  
Soft Story ◽  
Collapse Mechanisms

The use of BRBs into a typical European building with braced structure, whereby all the beam-to-column connections are perfectly pinned, may be low effective. In fact, these structures are low-redundant and prone to develop soft story collapse mechanisms. The concentration of drift demand in few stories precludes the full exploitation of the deformation capacity of all the BRBs inserted into the frame, and it partially reduces the benefit they can provide. A more effective structural system may be obtained by coupling frames with BRBs with frames with semi-rigid connections. This paper proposes a design procedure for this dual system and presents the calibration of the behavior factor. To this end, a set of frames is designed considering several values of behavior factor and the response of the obtained frames is determined by nonlinear dynamic analysis. Hence, the behavior factor that allows the frames to meet the performance objective requirement of EuroCode 8 is determined.

scholarly journals Functional catastrophe analysis of collapse mechanisms for deep tunnels based on the Hoek-Brown failure criterion

2014 ◽  
Vol 15 (9) ◽  
pp. 723-731 ◽  
Author(s):  
Cheng-ping Zhang ◽  
Kai-hang Han ◽  
Qian Fang ◽  
Ding-li Zhang
Keyword(s):  
Failure Criterion ◽  
Collapse Mechanisms
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