Carbon dioxide (CO2) was used as activator to produce much porous structure with various pore diameter. The CS hydrogel was synthesized through its grafting onto poly(N-isopropylacrylamide), acetylation of methacryloyl groups and incorporation into photothermal carbon. These copolymer systems exhibit a solution–gel transition at close to human body temperature that permits their application as injectable implants (Samchenko et al., 2011). The hydrogels are three-dimensional hydrophilic polymer networks of either chemically or physically cross-linked polymers, which undergo swelling following absorption of many times their weight in water. [9][10] The drop in viscosity can be indirectly observed. S. Saeki, N. Kuwahara, M. Nakata, M. Kaneko. Thermo-responsive polymers are the most comprehensively studied responsive polymers because of their unique property of sol–gel transition above certain temperature. Shape memory polymers have also been used in conjunction with Nanocellulose to fabricate composites exhibiting both chiroptical properties and thermo-activated shape memory effect. The thermo-activated reprocessing ability of a chemically crosslinked epoxidized natural rubber (ENR) is investigated. The extent of phase separation in a given temperature interval depends on the particular polymer-solvent phase diagram. That means that the gel could re-dissolve in a good solvent under some conditions. Further, the pNIPAM polymer can be conjugated with poly-(acrylic acid) to form a temperature and pH dual-responsive poly(N-isopropylacrylamide)-block-poly-(acrylic acid) copolymer [80]. m Also, the hydrogel exhibited sufficiently high MR relaxivity value (r2 = 173 mM− 1 s− 1) for MR imaging. Daniela Pamfil, Cornelia Vasile, in Polymeric Nanomaterials in Nanotherapeutics, 2019. It is convenient to add the glass transition curve to the phase diagram, although it is no real equilibrium. [86] developed novel, temperature-sensitive poly[N-isopropylacrylamide-co-2-hydroxyethylacrylate] [P(NIPAAmHEAc)] colloidal crystals containing β-CD for the slow and controlled release of 5-fluorouracil. In the field of “active materials” (e.g. In the swollen state, previously incorporated drugs are released easily by diffusion. The most common behaviour of these materials is characterized by polymer solutions that appear monophasic below a specific lower critical solution temperature (LCST), and biphasic above it. Tomasz Śliwa, Maciej Jarzębski, Ewa Andrzejewska, Mikołaj Szafran and Jacek Gapiński, Uptake and controlled release of a dye from thermo-sensitive polymer P(NIPAM- co -Vim), Reactive and Functional Polymers, 10.1016/j.reactfunctpolym.2017.04.003, 115, (102-108), (2017). They include the direct photoetching under UV-lamp irradiation and the direct writing by a cw laser beam on a polymethylmetacrylate (PMMA) film and some other polymeric materials. The thermo-responsive polymers are those, which are associated with temperature stimulus. Δ For a polymer in aqueous solution, LCST is the point in the phase diagram at which entropy of the water in the system increases due to less ordered arrangement of water molecules and becomes more than enthalpy of water hydrogen bonded to the polymer (Kumar, Srivastava, Galaev, & Mattiasson, 2007), therefore entropy of system governs LCST, and enthalpy of system governs UCST (Southall, Dill, & Haymet, 2002). An effective process of chemical treatment with dilute sulfuric acid was conducted to improve the thermal stability of primary fibers for further heating treatment. Zhang et al. Unlike thermo-softening polymers these thermosetting polymers are cross-linked to one another can you think about how this might affect the properties of these polymers? Temperature-responsive polymers or thermoresponsive polymers are polymers that exhibit a drastic and discontinuous change of their physical properties with temperature. Alteration in temperature triggers the delivery of drug, which may be because of enhanced temperature of body or due to external temperature (e.g., heat-triggered subdermal implants). The intersection of the glass transition curve with the cloud point curve is called Berghmans point. Salecan is known as a water soluble polysaccharide created by a salt-tolerant strain Agrobacterium sp. Curves showing phase transition phenomenon. Thermoresponsive polymers belong to the class of stimuli-responsive materials, in contrast to temperature-sensitive (for short, thermosensitive) materials, which change their properties continuously with environmental conditions. It is so used commonly due to its phase transition property as it occurs at approximately body temperature. The thermo-responsive polymers normally have a critical working temperature, above which the polymers present significantly different properties from below this temperature. The recent progress in the synthetic stimulus-responsive polymers has been discussed with focus pH-responsive, photo-responsive, and thermo-responsive polymers. The ideal entropy of mixing of multiple pure compounds is always positive (the term -T∙ΔS is negative) and ΔG would be negative for all compositions, causing complete miscibility. The combination of the two polymers exhibited a thermosensitive response with a phase transition temperature at 32 °C and 34 °C, respectively, close to that of the PNIPAAm homopolymer. ⋅ Usually these polymers have both hydrophilic and hydrophobic phases, and undergo abrupt changes in their electrostatic and hydrophobic interactions in an aqueous medium at a critical solution temperature. Their highly porous structure permits loading of drugs into the gel's matrix, with subsequent drug release occurring at a rate dependent on the diffusion coefficient. 1 Related polymers such as poly(N,N-diethyl acrylamide), poly(dimethylaminoethyl methacrylate), and poly(N-(L)-(1-hydroxymethyl)propylmethacrylamide), with LCSTs in the range 30–50 °C, were also investigated. Recent studies have shown that both hydrogen bonding and hydrophobic interactions in polymer solvent system are responsible for phase transition and hydrated random coil to hydrophobic globule transition above critical solution temperatures (Lin, Chen, & Liang, 1999; Volpert, Selb, & Candau, 1998). (2015) focused on chimeric advanced drug-delivery systems based on thermo-sensitive liposomes, combining lipids and thermo-responsive polymers. The ω-dithioester group of each polymer chain could quantitatively be either removed with AIBN treatment or substituted with a PFP ester by using a modified diazo compound. At the volume phase transition temperature (VPTT) the degree of swelling changes drastically. [12] The cloud point can be affected by many structural parameters of the polymer like the hydrophobic content,[26][27][28][29][30] architecture[26][27] and even the molar mass. To obtain excellent drug release kinetics and various thermo-sensitive functionalities, a strategy for preparing thermo-sensitive liposomes is conjugating thermo-sensitive polymers, as triggered parts of thermo-sensitive liposomes, in liposomal membranes (Hayashi et al., 1999). Δ Tailoring the temperature that the polymer solution gels can be challenging because this depend by many factors like the polymer composition,[26][27][28][29] architecture[26][27] as well as the molar mass. Thermally Activated Energy Dissipation in Semi-Crystalline Polymer Nanocomposites Significance Statement It has been observed that polymers as well as nanocomposites with presence of carbon nanotubes exhibit coupled thermo-mechanical properties which can be used for energy dissipation and damping undesired vibrations. [41], Polymer solutions that show thermoresponsivity in water are especially important since water as a solvent is cheap, safe and biologically relevant. The workers found that the scanning electron microscopy images exhibited excellent distribution of silver nanoparticles on the fabric surface. T The aqueous solutions of these polymers exhibit a critical solution temperature at which the solubility phase of the polymer is changed. layer approach, where the curing process is activated by an ultra-violet (UV) light. Thermoresponsive polymer chains in solution adopt an expanded coil conformation. x Physiologically, this stimuli is essential, viz. The ex vivo screening of porcine skin was used to evaluate the permeation ability of the nanogels. ATLANTA CHEMICAL ENGINEERING offers NON-TOXIC Thermochromic Powder Pigments. Thermo-responsive or temperature-sensitive hydrogels and polymers are mainly considered for stimuli-responsive polymeric system [61,64,65]. It was found that incubation of microspheres in PBS and Tris-HCl buffers at pH 7.4 exhibited the influence of ion- chelating phosphate on the matrix erodability which proposed an inherently A activation via changing the pH near the neutral value. With straightforward polymer science one color to another or color to another color. Insoluble below it exhibit upper critical solution temperature at which UCST behavior organic! Gradient elution, thermoresponsive polymers featuring the appropriate combination of structural characteristics,.! Very interesting area of research in the case of polymer phase diagrams thermoresponsive... 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