Synthesis and Lcst Behavior of Thermally Responsive Poly(N-Isopropylacrylamide)/Layered Silicate Nanocomposites

1996 ◽  
Vol 457 ◽  
Author(s):  
Phillip B. Messersmith ◽  
F. Znidarsich
Keyword(s):  
Aqueous Suspension ◽  
Layered Silicate ◽  
Polymer Nanocomposite ◽  
Solution Temperature ◽  
Stimuli Responsive ◽  
Thermally Responsive ◽  
Isopropyl Acrylamide ◽  
Lcst Behavior ◽  
Hydrogel Composites

ABSTRACTStimuli responsive polymeric hydrogel composites were synthesized by room temperature copolymerization of N-isopropyl acrylamide and methylene bisacrylamide (crosslinking monomer) in an aqueous suspension of Na-montmorillonite. Hydrogels containing 3.5 weight % of montmorillonite exhibited a lower critical solution temperature (LCST) similar to unmodified PNIPAM hydrogel (approximately 32°C), and underwent a reversible 60–70% volume shrinkage when heated from ambient temperature to above the LCST. However, hydrogels containing 10 weight% montmorillonite did not exhibit a measurable LCST, and underwent considerably less shrinkage when heated. A solvent exchange reaction was used to replace the water with an acrylic monomer, which was polymerized in-situ to create a delaminated montmorillonite/polymer nanocomposite.

scholarly journals Thermally responsive polymeric hydrogel brushes: synthesis, physical properties and use for the culture of chondrocytes

2006 ◽  
Vol 4 (12) ◽  
pp. 117-126 ◽  
Author(s):  
John Collett ◽  
Aileen Crawford ◽  
Paul V Hatton ◽  
Mark Geoghegan ◽  
Stephen Rimmer
Keyword(s):  
Crosslink Density ◽  
Cell Attachment ◽  
Viable Cell ◽  
Contact Angles ◽  
Polymer Chains ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Thermally Responsive ◽  
Isopropyl Acrylamide ◽  
Responsive Polymer

Hydrogel brushes are materials composed of a water-swollen network, which contains polymer chains that are grafted with another polymer. Using a thermally responsive polymer, poly( N -isopropyl acrylamide) (polyNIPAM), as the graft component we are able to maintain the critical solution temperature ( T crit ), independent of the overall composition of the material, at approximately 32°C. The change in swelling at T crit is a function of the amount of polyNIPAM in the system. However, there is a much smaller change in the surface contact angles at T crit . PolyNIPAM-based materials have generated considerable interest, as ‘smart’ substrates for the culture of cells and here, we show the utility of hydrogel brushes in cell culture. Chondrocytes attached to the hydrogel brushes and yielded viable cell cultures. Moreover, the chondrocytes could be released from the hydrogel brushes without the use of proteases by reducing the temperature of the cultures to below T crit to induce a change in the conformation of the polyNIPAM chain at T crit . The importance of the crosslink hydrogel component is illustrated by significant changes in cell attachment/cell viability as the crosslink density is changed.

Nanocomposite coatings with stimuli-responsive catalytic activity

RSC Advances ◽  
2014 ◽  
Vol 4 (34) ◽  
pp. 17579-17586 ◽  
Author(s):  
Meike Koenig ◽  
David Magerl ◽  
Martine Philipp ◽  
Klaus-Jochen Eichhorn ◽  
Martin Müller ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Metallic Nanoparticles ◽  
Nanocomposite Coatings ◽  
Stimuli Responsive ◽  
Isopropyl Acrylamide ◽  
Vinyl Pyridine

Stimuli-responsive catalytic coatings are fabricated by in situ-synthesis of metallic nanoparticles in binary poly(N-isopropyl acrylamide)–poly(2-vinyl pyridine) brushes.

Preparation of Low-K Fluorinated Polyimide/Phlogopite Nanocomposites

2008 ◽  
Vol 47-50 ◽  
pp. 987-990
Author(s):  
Yi He Zhang ◽  
Qing Song Su ◽  
Li Yu ◽  
Li Bing Liao ◽  
Hong Zheng ◽  
...  
Keyword(s):  
In Situ Polymerization ◽  
Layered Silicate ◽  
Polymer Nanocomposite ◽  
Nanocomposite Films ◽  
Polymerization Process ◽  
Ultrasonic Dispersion ◽  
Thermal Stabilities ◽  
Fluorinated Polyimide ◽  
Polyimide Matrix

Phlogopite with layered silicate structure had been firstly chemically modified via an in situ intercalation method, and phlogopite-polymer nanocomposite films were prepared from 2,2'-bis (3,4-dicarboxyphenyl) hexafluropropane dianhydride (6FDA) and oxydimethyl aniline (ODA) in N,N-dimethylacetamide as a solvent by using in-situ polymerization process combined with ultrasonic dispersion and multi-step curing. The structure of phlogopite minerals and its polymer nanocomposites were characterized by X-ray diffraction (XRD) and infrared spectra (FTIR) respectively. The experimental results indicated that the phlogopites with layered nanostructure had lost their ordered structure and had been exfoliated or intercalated. Thereafter, they were dispersed randomly in the polyimide matrix. The dependence of dielectric properties and thermal stabilities of the nanocomposite films on the phlogopite content and frequency were studied.

Encapsulation of Stimuli-Responsive Fusion Proteins in Silica: Thermally Responsive Metal Ion-Sensitive Hybrid Membranes

2013 ◽  
Vol 1498 ◽  
pp. 169-175
Author(s):  
Linying Li ◽  
Owen Im ◽  
Ashutosh Chilkoti ◽  
Gabriel P. López
Keyword(s):  
Fusion Proteins ◽  
Metal Ion ◽  
Sol Gel ◽  
Solution Temperature ◽  
Hybrid Membranes ◽  
Stimuli Responsive ◽  
Critical Solution Temperature ◽  
Thermally Responsive ◽  
Sol Gel Process ◽  
Sequential Addition

ABSTRACTIn this study, we demonstrate the fabrication of hybrid membranes that exhibit discrete and reversible changes in permeability in response to changes in calcium ion (Ca2+) concentration and temperature. Fusion proteins comprising calmodulin (CAM) and elastin-like polypeptides (ELPs) were used as stimuli-responsive elements due to their ability to undergo a reversible lower critical solution temperature (LCST) phase transition, which is sensitive to Ca2+ binding. The calmodulin elastin-like polypeptides fusions (CAM-ELPs) were incorporated into polymerizing silica networks using a simple sol-gel process and spin coating. Permeation experiments with solutions of crystal violet showed that the membranes are both Ca2+-responsive and thermally responsive. Under suitable pressure drop across the membranes, in the absence of Ca2+ or below the LCST of the ELPs, the hybrid membranes are impermeable to water. After addition of Ca2+ or above the LCSTs, they become permeable to water. The permeability can be toggled back and forth by sequential addition of calcium and ethylenediamine tetraacetic acid (EDTA). These results demonstrate that CAMELP/silica hybrid membranes can serve as tunable molecular filters whose permeability can be switched on and off in response to Ca2+ and temperature.

Polydopamine Nanoparticle for Poly(N-Isopropylacrylamide)-Based Nanocomposite Hydrogel with Good Free-Radical-Scavenging Property

2016 ◽  
Vol 848 ◽  
pp. 94-98 ◽  
Author(s):  
Shu Qiang Xiong ◽  
Yan Wang ◽  
Jing Zhu ◽  
Zu Ming Hu ◽  
Jun Rong Yu
Keyword(s):  
Free Radical ◽  
Radical Scavenging ◽  
Antioxidant Property ◽  
Solution Temperature ◽  
Scavenge Activity ◽  
Initial Reaction ◽  
Critical Solution Temperature ◽  
Nanocomposite Hydrogels ◽  
Isopropyl Acrylamide

Nanocomposite hydrogels (NC gels) consisting of poly (N-Isopropyl acrylamide) (pNIPAM)/polydopamine nanoparticles (PDAPs) were prepared by in-situ-free-radical polymerization of N-isopropyl acrylamide in the presence of modified PDAP in aqueous solution. The composition of the NC gels could be controlled directly by altering the composition of the initial reaction mixture. The lower critical solution temperature (LCST) of the NC gels were studied by DSC, and the LCST of both of pure pNIPAM hydrogel and NC gels was at 34°C. Besides, the NC gels showed superior antioxidant property, and the ability to scavenge activity of NC gel was up to 70% with the addition of 6 wt% modified PDAP into pNIPAM.

Thermosensitive Nanocontainers Prepared from Poly(N-isopropylacrylamide-co-N-(hydroxylmethyl)acrylamide)-g-Poly(lactide)

2006 ◽  
Vol 6 (9) ◽  
pp. 2896-2901 ◽  
Author(s):  
Yan Zhang ◽  
Wuli Yang ◽  
Changchun Wang ◽  
Wei Wu ◽  
Shoukuan Fu
Keyword(s):  
Self Assembly ◽  
Solution Temperature ◽  
Temperature Sensitive ◽  
Critical Solution Temperature ◽  
Spherical Structure ◽  
Thermally Responsive ◽  
Transmission Electron ◽  
Isopropyl Acrylamide ◽  
Fundamental Research ◽  
Spatial Specificity

Thermally-responsive graft copolymer of poly(N-isopropylacrylamide-co-N-(hydroxylmethyl)acrylamide)-g-poly(lactide) was synthesized by ring-opening polymerization of D,L-lactide (LA). The polymerization was initiated by the hydroxy group of poly(N-isopropyl acrylamide-co-N-(hydroxylmethyl)acrylamide), using stannous octoate as catalyst. The resulting polymer was temperature-sensitive and the lower critical solution temperature (LCST) was affected by their composition. The chemical structure and physical properties of the grafted copolymers were investigated by various methods. Nanocontainers formed from the self-assembly of poly(N-isopropylacrylamide-co-N-(hydroxylmethyl) acrylamide)-g-poly(lactide) were characterized by transmission electron microscopy (TEM), and a spherical structure was observed. Dynamic light scattering (DLS) results indicate that the particle size increased with the increase of polylactide content in the copolymer. The properties of this polymer are interesting for both industrial application and fundamental research. In particular it will combine a spatial specificity in a passive manner and a temperature-responsive active targeting mechanism for drug delivery system.

Smart Polymers and their Applications: A Review

2017 ◽  
Vol 8 (03) ◽  
Author(s):  
Gore S. A. ◽  
Gholve S. B. ◽  
Savalsure S. M. ◽  
Ghodake K. B. ◽  
Bhusnure O. G. ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Water Soluble ◽  
Solution Temperature ◽  
Smart Polymers ◽  
Stimuli Responsive ◽  
Responsive Materials ◽  
Water Soluble Polymers ◽  
Commercial Applications ◽  
Stimuli Sensitive ◽  
External Stimuli

Smart polymers are materials that respond to small external stimuli. These are also referred as stimuli responsive materials or intelligent materials. Smart polymers that can exhibit stimuli-sensitive properties are becoming important in many commercial applications. These polymers can change shape, strength and pore size based on external factors such as temperature, pH and stress. The stimuli include salt, UV irradiation, temperature, pH, magnetic or electric field, ionic factors etc. Smart polymers are very promising applicants in drug delivery, tissue engineering, cell culture, gene carriers, textile engineering, oil recovery, radioactive wastage and protein purification. The study is focused on the entire features of smart polymers and their most recent and relevant applications. Water soluble polymers with tunable lower critical solution temperature (LCST) are of increasing interest for biological applications such as cell patterning, smart drug release, DNA sequencing etc.

scholarly journals Thermo- and Photoresponsive Behaviors of Dual-Stimuli-Responsive Organogels Consisting of Homopolymers of Coumarin-Containing Methacrylate

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 329
Author(s):  
Seidai Okada ◽  
Eriko Sato
Keyword(s):  
Functional Group ◽  
Solution Temperature ◽  
Stimuli Responsive ◽  
Critical Solution Temperature ◽  
Equilibrium Degree ◽  
Stimuli Responsive Polymers ◽  
Responsive Polymers ◽  
Dual Functional ◽  
Wide Range ◽  
Increasing Temperature

Coumarin-containing vinyl homopolymers, such as poly(7-methacryloyloxycoumarin) (P1a) and poly(7-(2′-methacryloyloxyethoxy)coumarin) (P1b), show a lower critical solution temperature (LCST) in chloroform, which can be controlled by the [2 + 2] photochemical cycloaddition of the coumarin moiety, and they are recognized as monofunctional dual-stimuli-responsive polymers. A single functional group of monofunctional dual-stimuli-responsive polymers responds to dual stimuli and can be introduced more uniformly and densely than those of dual-functional dual-stimuli-responsive polymers. In this study, considering a wide range of applications, organogels consisting of P1a and P1b, i.e., P1a-gel and P1b-gel, respectively, were synthesized, and their thermo- and photoresponsive behaviors in chloroform were investigated in detail. P1a-gel and P1b-gel in a swollen state (transparent) exhibited phase separation (turbid) through a temperature jump and reached a shrunken state (transparent), i.e., an equilibrium state, over time. Moreover, the equilibrium degree of swelling decreased non-linearly with increasing temperature. Furthermore, different thermoresponsive sites were photopatterned on the organogel through the photodimerization of the coumarin unit. The organogels consisting of homopolymers of coumarin-containing methacrylate exhibited unique thermo- and photoresponsivities and behaved as monofunctional dual-stimuli-responsive organogels.

scholarly journals UHMWPE-layered silicate nanocomposites by in situ polymerization with tris(pyrazolyl)borate titanium/clay catalyst

2009 ◽  
Vol 20 (3) ◽  
pp. 472-477 ◽  
Author(s):  
Fernando Junges ◽  
Mariana S. Beauvalet ◽  
Bárbara C. Leal ◽  
Adriana C. A. Casagrande ◽  
Fábio F. Mota ◽  
...  
Keyword(s):  
In Situ Polymerization ◽  
Layered Silicate ◽  
Silicate Nanocomposites ◽  
Clay Catalyst
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