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Статті в журналах з теми "Thermosensitive behaviour":
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Xiao, Heng, Otto Bruhns, and Albert Meyers. "Thermoinduced plastic flow and shape memory effects." Theoretical and Applied Mechanics 38, no. 2 (2011): 155–207. http://dx.doi.org/10.2298/tam1102155x.
Анотація:
We propose an enhanced form of thermocoupled J2-flow models of finite deformation elastoplasticity with temperature-dependent yielding and hardening behaviour. The thermomechanical constitutive structure of these models is rendered free and explicit in the rigorous sense of thermodynamic consistency. Namely, with a free energy function explicitly introduced in terms of almost any given form of the thermomechanical constitutive functions, the requirements from the second law are identically fulfilled with positive internal dissipation. We study the case when a dependence of yielding and hardening on temperature is given and demonstrate that thermosensitive yielding with anisotropic hardening may give rise to appreciable plastic flow either in a process of heating or in a cyclic process of heating/cooling, thus leading to the findings of one- and two-way thermoinduced plastic flow. We then show that such theoretical findings turn out to be the effects found in shape memory materials, such as one- and two-way memory effects. Thus, shape memory effects may be explained to be thermoinduced plastic flow resulting from thermosensitive yielding and hardening behaviour. These and other relevant facts may suggest that, from a phenomenological standpoint, thermocoupled elastoplastic J2-flow models with thermosensitive yielding and hardening may furnish natural, straightforward descriptions of thermomechanical behaviour of shape memory materials.
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Sergeeva, Olga, Petr S. Vlasov, Nina S. Domnina, Anna Bogomolova, Petr V. Konarev, Dmitri I. Svergun, Zuzana Walterova, Jiri Horsky, Petr Stepanek, and Sergey K. Filippov. "Novel thermosensitive telechelic PEGs with antioxidant activity: synthesis, molecular properties and conformational behaviour." RSC Adv. 4, no. 79 (2014): 41763–71. http://dx.doi.org/10.1039/c4ra06978a.
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Hori, Tetsuro, Toshikazu Kiyohara, Yutaka Oomura, Hitoo Nishino, Shuji Aou, and Ichiro Fujita. "The responses of monkey preoptic thermosensitive neurons during thermoregulatory cooling behaviour." Neuroscience Research Supplements 5 (January 1987): S93. http://dx.doi.org/10.1016/0921-8696(87)90200-3.
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Rossi, Barbara, Valentina Venuti, Francesco D'Amico, Alessandro Gessini, Andrea Mele, Carlo Punta, Lucio Melone, et al. "Toward an understanding of the thermosensitive behaviour of pH-responsive hydrogels based on cyclodextrins." Soft Matter 11, no. 29 (2015): 5862–71. http://dx.doi.org/10.1039/c5sm01093d.
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Ilic-Stojanovic, Snezana, Ljubisa Nikolic, Vesna Nikolic, Mihajlo Stankovic, Jakov Stamenkovic, Ivana Mladenovic-Ranisavljevic, and Slobodan Petrovic. "Influence of monomer and crosslinker molar ratio on the swelling behaviour of thermosensitive hydrogels." Chemical Industry and Chemical Engineering Quarterly 18, no. 1 (2012): 1–9. http://dx.doi.org/10.2298/ciceq110711040i.
Анотація:
The synthesis of the poly(N-isopropylacrylamide-co-2-hydroxypropylmethacrylate) hydrogel along with the analysis of the residual monomers content and influence of monomer and crosslinker molar ratios on the swelling behaviour was investigated. Synthesis of thermosensitive hydrogel based on N-isopropylacrylamide was carried out with the molar ratios of 5, 10, 15 and 20 mol. % of monomer 2- hydroxypropyl-methacrylate, in the presence of ethylene glycol dimethacrylate as a crosslinker (1, 1.5, 2 and 3 mol. %) and 2,2'-azobis(2-methylpropionitril) as an initiator in acetone. The quantities of residual monomers in the synthesized copolymers were determined by HPLC method, ranging from 0.19 to 0.49 % for N-isopropylacrylamide and from 0.13 to 0.63 % for 2-hydroxypropyl-methacrylate, counting the amount of xerogel. The hydrogels swelling ratio depending on time at 20 and 40?C was examined. It was found that hydrogel with 5 mol. % 2-hydroxypropyl-methacrylate and 1 mol. % ethylene glycol dimethacrylate had the highest degree of swelling (? = 29.59) at 20?C, and that hydrogel with 20 mol. % 2-hydroxypropyl-methacrylate and 3 mol. % ethylene glycol dimethacrylate had the lowest swelling degree (? = 2.17) at 40?C.
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Lamba, Navneet Kumar. "Thermosensitive Response of a Functionally Graded Cylinder with Fractional Order Derivative." International Journal of Applied Mechanics and Engineering 27, no. 1 (March 1, 2022): 107–24. http://dx.doi.org/10.2478/ijame-2022-0008.
Анотація:
Abstract The present paper deals with thermal behaviour analysis of an axisymmetric functionally graded thermosensitive hollow cylinder. The system of coordinates are expressed in cylindrical-polar form. The heat conduction equation is of time-fractional order 0 < α ≤ 2, subjected to the effect of internal heat generation. Convective boundary conditions are applied to inner and outer curved surfaces whereas heat dissipates following Newton’s law of cooling. The lower surface is subjected to heat flux, whereas the upper surface is thermally insulated. Kirchhoff’s transformation is used to remove the nonlinearity of the heat equation and further it is solved to find temperature and associated stresses by applying integral transformation method. For numerical analysis a ceramic-metal-based functionally graded material is considered and the obtained results of temperature distribution and associated stresses are presented graphically.
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Voycheva, Christina, Marta Slavkova, Teodora Popova, Diana Tzankova, Denitsa Stefanova, Virginia Tzankova, Ivelina Ivanova, et al. "Thermosensitive Hydrogel-Functionalized Mesoporous Silica Nanoparticles for Parenteral Application of Chemotherapeutics." Gels 9, no. 9 (September 21, 2023): 769. http://dx.doi.org/10.3390/gels9090769.
Анотація:
Hydrogels can offer many opportunities for drug delivery strategies. They can be used on their own, or their benefits can be further exploited in combination with other nanocarriers. Intelligent hydrogels that react to changes in the surrounding environment can be utilized as gatekeepers and provide sustained on-demand drug release. In this study, a hybrid nanosystem for temperature- and pH-sensitive delivery was prepared from MCM-41 nanoparticles grafted with a newly synthesized thermosensitive hydrogel (MCM-41/AA-g-PnVCL). The initial particles were chemically modified by the attachment of carboxyl groups. Later, they were grafted with agar (AA) and vinylcaprolactam (VCL) by free radical polymerization. Doxorubicin was applied as a model hydrophilic chemotherapeutic drug. The successful formulation was confirmed by FT-IR and TGA. Transmission electron microscopy and dynamic light scattering analysis showed small particles with negative zeta potential. Their release behaviour was investigated in vitro in media with different pH and at different temperatures. Under tumour simulating conditions (40 °C and pH 4.0), doxorubicin was almost completely released within 72 h. The biocompatibility of the proposed nanoparticles was demonstrated by in vitro haemolysis assay. These results suggest the possible parenteral application of the newly prepared hydrogel-functionalized mesoporous silica nanoparticles for temperature-sensitive and pH-triggered drug delivery at the tumour site.
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Gutierres, A., S. Pascual, L. Fontaine, S. Piogé, and L. Benyahia. "The effect of metal ions on the viscoelastic properties of thermosensitive sol-to-gel reversible metallo-supramolecular hydrogels." Polymer Chemistry 9, no. 18 (2018): 2494–504. http://dx.doi.org/10.1039/c7py02118f.
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Geever, Luke M., César M. Mínguez, Declan M. Devine, Michael J. D. Nugent, James E. Kennedy, John G. Lyons, Austin Hanley, Sinead Devery, Paul T. Tomkins, and Clement L. Higginbotham. "The synthesis, swelling behaviour and rheological properties of chemically crosslinked thermosensitive copolymers based on N-isopropylacrylamide." Journal of Materials Science 42, no. 12 (March 8, 2007): 4136–48. http://dx.doi.org/10.1007/s10853-006-0912-z.
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Wang, Xiaoyun, and Jing Zhang. "Temperature-sensitive poly(N-isopropylacrylamide) (PNIPAAm) stabilized size controllable synthesis of silver nanoparticles and its improved antimicrobial activity for wound healing and nursing care after femoral fracture during surgery." Materials Express 11, no. 1 (January 1, 2021): 73–84. http://dx.doi.org/10.1166/mex.2021.1878.
Анотація:
In this research, a thermo-sensitive copolymer PNIPAAm-co-MHq was used to successfully synthesize different nano sizes silver nanoparticles in the ranges between 1.5 to 4 nm with uniform dispersion. The polymeric assisted synthesized Ag nanoparticles (AgNPs@PM) exhibited reasonable solution stability and thermalresponsive behaviour. In specific, AgNPs@PM3 (1.59 nm) displayed improved bacterial resistance against clinically approved anti-biotic resistant bacterial pathigens with very low MIC value (4.05 μg/mL). Subsequently, the thermal responsive polymeric molecular structure on AgNPs synthesis has been established that significant temperature dependened anti-bacterial efficiency. It was also observed that the nonparticipants size, temperature responses and proportion of thermosensitive copolymer also influenced the antibacterial efficacy of AgNPs@PM. Resulting thermal sensitive polymer nanocomposite can be extremely beneficial for wound healing treatment after femoral fracture surgery.
Дисертації з теми "Thermosensitive behaviour":
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Said-mohamed, Cynthia. "Thermosensitive gold nanoparticles : solution optical properties and interfacial behaviour." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00684389.
Анотація:
L'objectif de cette thèse est de contrôler les propriétés optiques des nanoparticules d'or greffées de polymère en modulant les propriétés structurales de la couche protectrice de polymères. Des nanoparticules greffées de polymères thermosensibles avec une large gamme de masse molaire et différents degrés d'hydrophobicité sont synthétisées par la méthode de " grafting-to ". La DNPA est utilisée pour caractériser les propriétés structurales de la couche protectrice de polymère. Les spectres d'absorption sont modélisés en utilisant la théorie de Mie. Nous démontrons que la sensibilité de la SPR à la propriété diélectrique du solvant diminue progressivement avec la fraction volumique de la couche de polymère jusqu'à devenir quasi-nulle; dans ce dernier cas de figure, la SPR est dite " gelée " par la couche de polymère. Un déplacement significatif de la bande de SPR vers le rouge est induit (un changement de couleur se produit) dû à une transition de collapse de la couche de polymère avec la température. La gamme de température pour induire ce déplacement dépend du degré d'hydrophobicité du polymère et de la salinité. Une partie important de cette thèse est également consacrée aux propriétés des nanoparticules d'or greffées de polymères à l'interface air-eau. La technique de Langmuir est utilisée pour former des films minces dont la distance entre particule est contrôlée par la compression, la longueur des chaînes du polymère greffé et la température. Les propriétés structurales des films minces sont étudiées en déterminant la conformation de la couche de polymère greffée et l'organisation du cœur de l'or par la réflectivité de neutron et de X, respectivement. Les mesures de réflectivité nous permettent également d'évaluer et d'améliorer la stabilité des films minces pour un meilleur control de la distance entre particule, aspect important pour l'optimisation de la SPR. Enfin, les propriétés optiques des nanoparticules d'or à l'interface sont mesurées par des mesures de transmission.
2
Said-Mohamed, Cynthia. "Thermosensitive gold nanoparticles : solution optical properties and interfacial behaviour." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112235/document.
Анотація:
L’objectif de cette thèse est de contrôler les propriétés optiques des nanoparticules d’or greffées de polymère en modulant les propriétés structurales de la couche protectrice de polymères. Des nanoparticules greffées de polymères thermosensibles avec une large gamme de masse molaire et différents degrés d’hydrophobicité sont synthétisées par la méthode de « grafting-to ». La DNPA est utilisée pour caractériser les propriétés structurales de la couche protectrice de polymère. Les spectres d’absorption sont modélisés en utilisant la théorie de Mie. Nous démontrons que la sensibilité de la SPR à la propriété diélectrique du solvant diminue progressivement avec la fraction volumique de la couche de polymère jusqu’à devenir quasi-nulle; dans ce dernier cas de figure, la SPR est dite « gelée » par la couche de polymère. Un déplacement significatif de la bande de SPR vers le rouge est induit (un changement de couleur se produit) dû à une transition de collapse de la couche de polymère avec la température. La gamme de température pour induire ce déplacement dépend du degré d’hydrophobicité du polymère et de la salinité. Une partie important de cette thèse est également consacrée aux propriétés des nanoparticules d’or greffées de polymères à l’interface air-eau. La technique de Langmuir est utilisée pour former des films minces dont la distance entre particule est contrôlée par la compression, la longueur des chaînes du polymère greffé et la température. Les propriétés structurales des films minces sont étudiées en déterminant la conformation de la couche de polymère greffée et l’organisation du cœur de l’or par la réflectivité de neutron et de X, respectivement. Les mesures de réflectivité nous permettent également d’évaluer et d’améliorer la stabilité des films minces pour un meilleur control de la distance entre particule, aspect important pour l’optimisation de la SPR. Enfin, les propriétés optiques des nanoparticules d’or à l’interface sont mesurées par des mesures de transmissionIn this thesis, the objective is to control the polymer-grafted gold nanoparticles optical properties (SPR) by tuning the protecting polymer shell structural properties. Gold nanoparticles grafted with thermosensitive polymers with a large range of molecular masses and different degrees of hydrophobicity are synthesized by “grafting-to” technique. SANS is employed to characterize the protecting polymer shell structural properties. The absorption spectra are modeled using the Mie Dipolar theory. It is shown that the gold nanoparticle sensitivity to external solvent is progressively reduced with increasing polymer volume fraction of the nanocomposite until the SPR is frozen by the polymer shell. In this case, the SPR mode becomes insensitive to the dielectric properties of the solvent. SPR is also red-shifted (a color change occurs) by thermally inducing the collapse of the polymer shell. The temperature and the extent of the red-shift are controlled by the graft polymer hydrophobicity and salinity. An important part of this thesis is also dedicated to the polymer-protected gold nanoparticles behaviour at the air-water interface. The Langmuir balance technique is used to build interfacial layers whose interparticle distance is modulated by compression, polymer graft chain length and temperature. The interfacial layer structural properties are determined by studying both the polymer graft layer conformation and the gold core organization with neutron and X-ray reflectivities. These reflectivitity measurements also enable us to evaluate and ameliorate the surface layers stability for a better control of the interparticle distance that is important for optimizing the SPR of the surface layer
3
Kiran, K. J. "Investigation of phase behaviour of neutral and ionic microgels using scattering, rheology and microscopy techniques." Thesis(Ph.D.), CSIR - National Chemical Laboratory, Pune, 2018. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/4539.
Анотація:
The thesis deals with the investigation of structure and dynamics of temperature and pH sensitive microgels of Poly (N-isopropylacrylamide) at very dense concentrations using scattering, rheology and microscopy techniques. The main focus of the work is on understanding how the microgel architecture/structure affects the flow properties as well as in applications. Poly (N-isopropyl acrylamide) microgels were prepared using two different synthesis procedures giving rise to core-shell particles and homogeneous particles respectively. These particles are then used to prepare dense suspensions to study non-linear rheological behaviour in the glassy region. Modern Light scattering techniques, rheology and confocal microscopy are used to investigate the role of microstructure in the flow properties of these dense suspensions. The thesis also deals with electric field induced structure formations in ionic microgels and mixtures. We also look at the effect of microgel particle morphology in a typical application like drug delivery.
Colloids are heterogeneous system where one substance is dispersed as very fine particles in another. The dispersion may be foam, emulsion or sols and are indispensable in or daily life. Study of the processing of all these colloids is important because many of the colloids we use as commercial products in our daily life is subjected to shear when use. They transform from elastic to a plastic state when yielded. The study of yielding in colloids is thus very much important to design the products. In addition to its utility as materials of daily use, colloidal suspensions are extensively used as model systems to study phase behavior of atomic or molecular systems. Phase transitions in colloidal suspensions can be studied in real time using optical techniques and are analogous to phase transitions in liquids. Experiments with colloids are always simpler. The microscopic size scale of colloids allows them to be easily characterized by microscopy and various light scattering techniques. Although lot of work has been done in understanding the yielding mechanism in hard sphere colloids and colloid-polymer mixtures, there is not much progress in understanding the yielding phenomena in soft colloids. First chapter sets the motivation and objectives of the study. This chapter also contains a literature survey and introductory remarks on colloids. Hard sphere colloids and soft sphere colloids, their properties, colloidal interactions and phase diagram are described here. A brief history on the investigation of electric field driven assembly of ionic colloids and a background on the drug release studies on model soft microgels are also provided. The second chapter deals with the synthesis and characterization of the microgels synthesized. A brief introduction to various experimental techniques used is also provided. In the third chapter, I try to address the yielding mechanism in dense thermosensitive microgels of Poly (N-Isopropylacrylamide) (PNIPAm) in the glassy region as a function of particle morphology and crosslinker content. Electric field driven assembly of negatively charged copolymer microgels of NIPAm and acrylic acid at different concentration regimes were investigated in the fourth chapter. The behaviour of a binary mixture of two different sized particles towards applied electric field is also under investigation. The intension of the work is to develop a phase diagram of binary mixture of particles under the electric field with respect to different concentrations and different ratios of particles. Fifth chapter will cover the study of the effect of particle morphology on the drug release from PNIPAm microgel particles. A water-soluble drug and a water insoluble drug were taken for the case study. Percentage drug release was measured using UV-Visible spectroscopy.
Second chapter provides the details of the synthesis of homo and copolymer microgels of NIPAm. Some of the preliminary characterizations of microgels using light scattering technique are also provided in this chapter. All the experimental techniques and the methods used in this work to investigate the structure and properties of microgels are explained. The technical part of instruments like 3D- Dynamic Light Scattering, rheology, confocal microscopy, UV-Visible Spectroscopy and Differential Scattering Calorimetry are elaborately discussed in this chapter. Light Scattering techniques are used to find the radius of gyration, hydrodynamic radius, swelling ratio and volume phase transition temperature of PNIPAm microgels. Yielding mechanism in the microgels was elucidated by Large Amplitude Oscillatory Shear experiments in a stress controlled rheometer. Electric field driven assembly of colloids were observed using confocal microscopy. Drug release studies were conducted and percentage release was found by UV-Visible spectroscopy. Subzero temperature DSC was done to analyse the changes thermodynamic property of water associated with the gelling process.
The results of the current work will be concluded in the sixth chapter. Ours is one of the first studies on the understanding of origin of double yielding mechanism in pure PNIPAm microgel system. Although two step yielding has been observed in attraction induced colloidal glasses, we are observing two step yielding in pure PNIPAM microgel glasses, which is otherwise repulsive. Two step yielding disappears with the change in morphology from core-brush type structure to homogeneously crosslinked structure. With increase in crosslinker content, and finally like hard-sphere colloids. Electric field driven assembly can be effectively used to tune the particles assembly in fluid regime and also at high concentrations. The works may be extended to mixture of oppositely charged particles, active particles and colloids, colloid-metal hybrid particles etc. Drug release ability of microgels can be enhanced by particle morphology changes.CSIR
AcSIR
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Chu, Fangfang. "Dumbbell-shaped colloids." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2014. http://dx.doi.org/10.18452/17062.
Анотація:
In der vorliegenden Arbeit wurde das Phasenverhalten von harten Hantelteilchen (Dumbbells) als Funktion des Aspektverhältnisses (L*, der Quotient aus dem Abstand der Massenzentren zum Durchmesser der Kugel) und der Volumendichte untersucht. Bragg-Reflexe weisen darauf hin, das harte Dumbbells mit L* < 0.4 einen Phasenübergang von einer Fluid-artigen Phase zu einem plastischen Kristall zeigen. Die experimentellen Phasendiagramme bei L* ~ 0.24 und L*~ 0.30 sind vergleichbar mit Vorhersagen aus Monte Carlo-Simulationen. Rheologie Messungen zeigen, dass harte Dumbbells verschiedene Gleichgewichts- und Nichtgleichgewichtsphasen annehmen. Suspensionen von harten Dumbbells im Zweiphasenbereich zeigen ein einziges Fließgrenzen-Ereignis, wohingegen in der plastischen Kristallphase zwei Fließgrenzen-Ereignisse beobachtet werden. Diese, im Folgenden als „double yielding“ bezeichneten Ereignisse, hängen mit der Kristallisation der Suspensionen von harten Dumbbells zusammen. Die entsprechende Strukturentwicklung wurde mit rheo-SANS-Experimenten untersucht und mithilfe von BD Simulationen interpretiert. Es konnte gezeigt werden, dass die plastische Kristallphase polykristallin im Ruhezustand ist. Unter schwacher Scherung wird eine fcc-Schwerzwilling Struktur ausgebildet. Bei hoher Scherung formt sich eine teilweise orientierte Struktur aus gleitenden Schichten. Zwischen diesen beiden Strukturen existiert eine ungeordnete Übergangsphase. Die Scher-induzierte Strukturausbildung eintspricht dem „double yielding“ Ereignis der kristallinen harten Dumbells. Es wurde gezeigt, dass ein größeres L* (L* < 0.4) die Strukturentwicklung unter Scherung qualitativ nicht beeinflusst. Aufgrund verlangsamter Dynamik in der Nähe des Glasübergangs sind lediglich stärkere oder längere Oszillationen von Nöten, um Scher-induzierte Kristallisation zu erzeugen. Im zweiten Teil dieser Arbeit werden Systeme aus hohlen Kugeln und „Janus“-Dumbbells vorgestellt, die als kolloidale Modellsysteme dienen können.In the present work the phase behaviour of hard dumbbells has been explored as a function of aspect ratio (L*, the center to center distance to the diameter of one composed sphere) and volume fractions using thermosensitive dumbbell-shaped microgels as the hard dumbbell model system. A fluid-to-plastic crystal phase transition indicated by Bragg reflections has been observed for L* < 0.4. The experimental phase diagrams at L* ~ 0.24 and L* ~ 0.30 are comparable to the theoretical prediction of the Monte Carlo simulations. Rheological measurements reveal that the hard dumbbells in the biphasic gap show the yielding behaviour with a single yielding event, while two yielding events have been observed for the plastic crystalline phase. The two yielding events, referred to as the double yielding behaviour, are proved to be related to the crystallization of hard dumbbells. The underlying structural evolution has been investigated by rheo-SANS experiments and the scattering data has been interpreted by BD simulations. It is demonstrated that the plastic crystal structure of the hard dumbbells is polycrystalline at rest, which has been induced into the twinned fcc structure at low strain, the partially oriented sliding layers at high strain and the intermediate state at the strain in-between. The shear-induced structural evolution corresponds to the double yielding events of the fully crystallized hard dumbbells. Additionally, we prove that the increase of L* (L* < 0.4) does not change the structural evolution of the sheared hard dumbbells. Only more extensive or longer oscillations are required to form the shear-induced crystal structures due to the slowdown of the dynamics in the vicinity of the glass transition. In a second part, the work of this thesis is extended to hollow systems composed of hollow spheres and hollow Janus dumbbells that can be used as model systems to probe phase behaviour of hollow capsules.
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Nouveau, Thibaut. "Nébulisation de nouveaux polyplexes pour le transfert de gènes." Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS734.pdf.
Анотація:
La thérapie génique est une forme de thérapie pour traiter les maladies génétiques héréditaires ou acquises tels que les cancers ou la mucoviscidose. L’introduction d’un polynucléotide, par voie systémique ou locale (orale ou nasale par exemple), au sein des cellules malades permet de corriger les défauts à l’origine des mutations génétiques. Néanmoins, le franchissement des différentes barrières biologiques nécessaire à l’internalisation de l’ADN ne peut se faire que par l’intermédiaire d’un vecteur qui va le protéger et lui permettre d’atteindre le noyau de la cellule où il sera transcrit. Divers vecteurs (viraux ou synthétiques) ont vu le jour, tels que des vecteurs polymères cationiques à base de PEI. Cependant, bien qu’efficaces, ces vecteurs sont immunogènes à forte dose. Des fonctionnalisations pour réduire cette toxicité, telle que la PEGylation, ont été mises au point et permettent de renforcer les vecteurs en apportant de la furtivité aux polyplexes finaux. Cependant, ces stratégies montrent des limites nécessitant la synthèse de nouveaux types de polymères. La POxylation représente une bonne alternative à l’utilisation du PEG pour former de nouveaux polyplexes par l’ajout d’un bloc formé d’une ou plusieurs poly(2-alkyl-2-oxazoline)s. Les copolymères sont synthétisés par hydrolyse sélective d’un copolymère triblocs PEtOx-b-PnPrOx-b-PMeOx en utilisant les propriétés thermosensibles des blocs hydrophobes et un sel kosmotrope afin de former des systèmes cœur-couronne permettant l’hydrolyse du bloc PMeOx en PEI. Les systèmes ont ensuite été formulés selon une formulation standard et une méthode par « micro-extrusion ». Les polyplexes ont ensuite été utilisés in vitro par déposition ou par une méthode de nébulisation, idéale pour le traitement de maladies pulmonaires. De très bons résultats de transfection ont été obtenus, résultats qui dépendent de différents paramètres (Mn, PEI, architecture polymère, rapport de charge +/-)Gene therapy is a form of therapy used to treat hereditary or acquired genetic diseases such as cancer or cystic fibrosis. Introducing a polynucleotide into diseased cells, either via the systmeic route or the local route (oral or nasal inhalation), corrects the defects causing the genetic mutations. However, DNA can only be internalized using a vector that protects it and enables it to reach the cell nucleus, where it will be transcribed. Various vectors (viral or synthetic) have been developed, such as PEI-based cationic polymer vectors. However, although effective, these PEI-based vectors are immunogenic at high doses. Functionalizations to reduce this toxicity, such as PEGylation, have been developed, making it possible to reinforce vectors by adding stealthiness to the final polyplexes. However, these strategies have their limitations, necessitating the synthesis of new types of polymer. POxylation represents a good alternative to PEG usage to form new polyplexes by adding a block formed from one or more poly(2-alkyl-2-oxazoline)s. The copolymers are synthesized by selective hydrolysis of a PEtOx-b-PnPrOx-b-PMeOx triblock copolymer using the thermosensitive properties of the hydrophobic blocks and a kosmotropic salt to form core-shell systems enabling hydrolysis of the PMeOx block to PEI. Then, the systems were formulated using a standard formulation and a "micro-extrusion" method. The polyplexes obtained were used in vitro experiments, by deposition or by a nebulization method, ideal for the treatment of pulmonary diseases. Very good transfection results were obtained, depending on various parameters (Mn, PEI, polymer architecture, +/- charge ratio)
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Chang, Ya-Ting, and 張雅婷. "Thermosensitive methylcellulose hydrogels：its gelation behavior and biocompatibility with MSCs." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/87200347472776164329.
Анотація:
碩士元智大學
生物科技暨生物資訊研究所
94
The phase transition behaviors and the gelation kinetics of the thermosensitive methylcellulose (MC) solution were studied and the MC gels were tested for the biocompatibility with mesenchymal stem cells (MSCs). The presence of NaCl (0.13 M) decreased the gelation temperature (or cloud point) and increased the rate of the gelation process due to the salting out effect. The gelation temperature decreased and the rate of gelation increased with the increase of MC concentration in the solution due to the chain entanglement effect at higher polymer concentrations. The gelation temperature of the salt-free MC solution approximated to 42 oC and that of the MC solution with 0.13 M NaCl approximated to 40 oC when the polymer concentration was higher than 9 wt%. When MSCs were cultured within the 3D MC gels, it was found that MSCs could aggregate and maintain their viability up to 28 days. The biocompatibility of MC gels with MSCs suggested that MC gels could be considered as an injectable hydrogel for tissue engineering application.
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Jiang, Xueguang. "Synthesis and Solution Behavior of Doubly Responsive Hydrophilic Block Copolymers." 2010. http://trace.tennessee.edu/utk_graddiss/809.
Анотація:
This dissertation presents the synthesis of stimuli-sensitive hydrophilic polymers, particularly doubly responsive hydrophilic block copolymers, by controlled radical polymerizations and the study of their solution behavior in water. By incorporating a small amount of stimuli-responsive groups into the thermosensitive block of a hydrophilic block copolymer, the lower critical solution temperature (LCST) of the thermosensitive block can be tuned by a stimulus and multiple micellization/dissociation transitions can be achieved by combining two external triggers. Chapter 1 describes the synthesis and thermosensitive properties of two new watersoluble polystyrenics with a short oligo(ethyl glycol) pendant from each repeat unit and the study of hydrophobic end group effects on cloud points of thermosensitive polystyrenics. Well-defined polymers were prepared from monomer-based initiators via nitroxide-mediated polymerization and the alkoxyamine end groups were removed by tri(n-butyl)tin hydride, yielding thermoresponsive polystyrenics with essentially no end groups. The results showed that hydrophobic end groups could significantly change the cloud points and the molecular weight dependences of cloud points of polystyrenics. Chapter 2 presents the synthesis of thermo- and light-sensitive hydrophilic block copolymers, poly(ethylene oxide)-b-poly(ethoxytri(ethylene glycol) acrylate-co-onitrobenzyl acrylate), and their responsive behavior in dilute aqueous solutions. Dynamic light scattering and fluorescence spectroscopy studies showed that these copolymers were molecularly dissolved in water at lower temperatures and self-assembled into micelles at temperatures above the LCST of the thermosensitive block. Upon UV irradiation, the oiv nitrobenzyl group was cleaved and the LCST of the thermosensitive block was increased, causing the dissociation of micelles into unimers. The resultant copolymers underwent thermo-induced reversible micellization at higher temperatures. Chapter 3 describes multiple micellization/dissociation transitions of thermo- and pH-sensitive hydrophilic block copolymers, poly(ethylene oxide)-b-poly(methoxydi(ethylene glycol) methacrylate-co-methacrylic acid), in response to temperature and pH changes. The LCST of the thermosensitive block can be reversibly tuned and precisely controlled by solution pH. Chapter 4 presents the study on multiple sol-gel-sol transitions of a 20.0 wt % aqueous solution of poly(ethylene oxide)-b-poly(ethoxytri(ethylene glycol) acrylate-co-o-nitrobenzyl acrylate) induced by temperature changes and UV irradiation. The solution underwent thermo-induced sol-gel-sol transitions. Upon UV irradiation to dissociate micelles, the gel was transformed into a free-flowing liquid, which upon heating underwent sol-gel-sol transitions again.
8
Huang, Zun-Huan, and 黃尊煥. "Temperature and size effect for the drug release behavior of thermosensitive hollow carrier." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/62009492036644017275.
Анотація:
碩士國立中興大學
材料科學與工程學系所
98
In this study, the hollow SiO2 particles coated by thermosensitive poly(N–isopropylacrylamide–co–3-trimethoxysilylpropylmethacrylate)(PNIPAM) have been fabricated through Layer-by-layer technique and radical polymerization. The 200nm and 600nm hollow SiO2 particles were first synthesized using 200nm and 600nm polystyrene(PS) particles served as a core and then coated by 13nm SiO2 nanoparticles using Layer-by-layer method. The PS particles were removed by tetrahydrofuran(THF) at 60°C to obtain hollow SiO2 particle. The hollow SiO2 particles were then coated by PNIPAM using radical polymerization to form the thermosensitive and hollow SiO2 particles. The characteristic and drug loading / release behavior of thermosensitive and hollow SiO2 particles were investigated using SEM, TEM, FT-IR, DSC, DLS and XPS. The DSC data indicated the Lower critical solution temperature (LCST) of thermosensitive and hollow SiO2 particles is in the range of 32~34°C, which is close to human temperature. These results reveal that the fabricated particles can be used as drug carrier. The poduced thermosensitive silica hollow sphere were applied to study the effectes of the shell thickness on the release efficiency for (flourescein isothiocyanate，FITC). The shell thickness of thermosensitive silica hollow sphere in 200 nm and 600 nm diameter was 13 nm and 35 nm, respectively; after increasing one SiO2 coating layer, the shell thickness was increased to 26 nm and 52 nm, respectively. The release profiles showed that the drug release decreased with increase of shell thickness. The release amount of FITC from thinner thermosensitive silica hollow spheres in 200 nm diameter is 86% at 25°C and 57% at 40°C, and decreasing to 80% and 25% after one additional layer coating, respectively. The result was also found in thermosensitive silica hollow spheres in 600 nm diameter, showing that the shell thickness is one of the main controlling factors for the system. In addition, the temperature also affect the release rate showed that PNIPAM play an important role in controlling release process.
9
Hsu, Cheng-Haw, and 許政皓. "Studies on the preparation and swelling behaviors of the cationic thermosensitive hydrogels." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/36372400424398862703.
Анотація:
碩士大同工學院
化學工程學系
85
A series of N-isopropylacrylamide/trimethyl acrylamidopropyle ammonium iodide(NIPAAm/TMAAI),N-isopropylacrylamide/trimethyl methacryloyloxyethyl ammonium iodide(NIPAAm/TMMAI),and N- isopropylacrylamide/3-methyl-1-vinyl--imidazolium iodide(NIPAAm/ MVI) copolymeric gels areprepared from the various molar ratios of NIPAAm, cationic monomer TMAAI,TMMAI,and MVI, and N,N''- methylene bisacrylamide(NMBA)in this article. The influences of the amount of the cationic monomers in the copolymeric gels on the swelling behaviors in water,various saline solutions,and various temperatures areinvestigated. Results show that tha swelling ratios of copolymeric gels are significantly larger than pure NIPAAm gel,and the more the monomer content,the higherthe gel transition temperature. In the saline solution, results show that the swelling ratio of pure NIPAAm gel has not significantly changed withan increase of the salt concentration until the salt concentration is larger than 0.1M. The swelling ratios for the copolymeric gels are decreasedwith increasing of the salt concentration. In various saline solution,results show that the anionic effects are greater than cationic effectsin the presence of common anion,different cations and common cation, different anions for these hydrogels. Finally, we also test the reversibility of the NIPAAm/TMMAI copolymericgels. The deswelling and reswelling kinetics are depended on the temperature which is below or above the gel transition temperature. The gel with little TMMAI content has a good reversibity.
10
Xu, Zheng-Hao, and 許政皓. "Studies on the preparation and swelling behaviors of the cationic thermosensitive hydrogels." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/00979989564807829057.
Тези доповідей конференцій з теми "Thermosensitive behaviour":
1
Qin, Xing, Youzhi Duan, Hui Yue, Shuang Ai, Qian Hou, and Bo Jing. "Mechanical Behavior of Thermosensitive Screen Applied for Wellbore Collapse." In SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers, 2020. http://dx.doi.org/10.2118/201581-ms.
2
Wang, Bo, Robbin Bertucci, Zhenqing Li, Raj Prabhu, Lakiesha Williams, Jianjun Guan, and Jun Liao. "Effect of Thermosensitive Hydrogel Injection on Mechanical Behavior of Porcine Myocardium." In ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14551.
Анотація:
Myocardial infarctions (MI) afflict approximately 1.1 million individuals in the United States each year and exhibit an increasing prevalence worldwide due to the improvement of economic levels. Injection therapies for MI using biodegradable biomaterials with/without cells have been recognized to stabilize and preserve mechanical properties in the infarcted area in pre-clinical animal models. Recently, thermally responsive hydrogels, which can be injected from a syringe below 37 °C and then solidified at body temperature, are considered an attractive material for injection therapy.[1] The advantages of using an injectable hydrogel lie in its high moldability, capability of filling irregular shaped defects, and ability to be delivered to the in vivo environment by limited surgical invasion. However, it is still not very clear how the injection of thermosensitive hydrogel affects local tissue structure and mechanics. Thus, the goal of this study is to investigate possible alterations in myocardial structure and mechanical behavior after hydrogel injection using a well-controlled in vitro model.
3
Ningrum, Eva Oktavia, Agus Purwanto, Hikmatun Ni’mah, Sumarno, Dinny Islamiah Dewitasari, and Eka Octaviyatna Mulyadi. "Ion adsorption and desorption behaviors of thermosensitive NIPAM-co-DMAAPS gel by temperature swing." In INTERNATIONAL SEMINAR ON FUNDAMENTAL AND APPLICATION OF CHEMICAL ENGINEERING 2016 (ISFAChE 2016): Proceedings of the 3rd International Seminar on Fundamental and Application of Chemical Engineering 2016. Author(s), 2017. http://dx.doi.org/10.1063/1.4982315.