Poly(N-Isopropylacrylamide) Microgel Synthesised by Emulsion Polymerization

2020 ◽  
Vol 307 ◽  
pp. 345-350
Author(s):  
Ernest Hsin Nam Yong ◽  
Kim Yeow Tshai ◽  
Siew Shee Lim ◽  
Ing Kong
Keyword(s):  
Main Chain ◽  
Hydrodynamic Diameter ◽  
Smart Polymers ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Thermally Responsive ◽  
Hydrogel Particles ◽  
Chemical Behaviour ◽  
External Stimuli ◽  
Average Hydrodynamic Diameter

Smart polymers have been one of the most popularly studied materials owing to their capability to alter physio-chemical behaviour upon exposure to specific external stimuli. The biocompatible thermally responsive poly (N-isopropylacrylamide), PNIPAm shows reversible transition between hydrophilic-hydrophobic characteristics at the vicinity of human physiological temperature has great potential to propel the development of smart tissue engineering scaffold and drug delivery. However, the limited availability and its high cost have dampened the extent of research on this polymer. To address these challenges, the current work demonstrates an economical lab-scale polymerization of crosslinked PNIPAm and the optimised parameters to produce mono-dispersed polymer hydrogel particles were investigated. Characterisation of the synthesized PNIPAm polymer revealed particle size polydispersity index of 0.215, indicative of distribution within the mono-dispersed range, with average hydrodynamic diameter of 346.3 nm. Zeta-potential of the synthesized PNIPAm was found to be -20.6 mV, suggesting an incipient instability in terms of colloidal coagulation. Viscosity of the synthesized PNIPAm (4 wt% concentration in methanol) was 28.6 cP. Thermal gravimetric analysis (TGA) indicated the thermal degradation of main chain PNIPAm fell in the range of 340 to 480°C.

Synthesis and Properties of Poly(3,4-Ethylenedioxythiophene) via Solid-State Polymerization

2011 ◽  
Vol 306-307 ◽  
pp. 261-264
Author(s):  
Shu Ai Chen ◽  
Jing Kun Xu ◽  
Dan Hua Zhu ◽  
Xue Min Duan
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Solid State ◽  
Main Chain ◽  
Conductivity Measurement ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Electrical Conductivity Measurement ◽  
Solid State Polymerization ◽  
Scanning Electron

Conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) has been synthesized by solid-state polymerization of 2,5-diiodo-3,4-ethylenedioxythiophene under normal conditions. The resulting iodine-doped PEDOT is completely insoluble in common organic solvents and retained partial crystal structure of monomer as indicated by scanning electron microscopy. Electrical conductivity measurement showed that PEDOT exhibited conductivity in the range of 0.16–0.23 S/cm (pressed powder pellet) with temperature dependence. Thermogravimetric and differential thermal gravimetric analysis of PEDOT indicated that its main chain was stable up to ca. 200 °C.

scholarly journals Coacervate Thermoresponsive Polysaccharide Nanoparticles as Delivery System for Piroxicam

2020 ◽  
Vol 21 (24) ◽  
pp. 9664
Author(s):  
Dorota Lachowicz ◽  
Agnieszka Kaczyńska ◽  
Anna Bodzon-Kulakowska ◽  
Anna Karewicz ◽  
Roma Wirecka ◽  
...  
Keyword(s):  
Delivery System ◽  
Water Solubility ◽  
Spherical Shape ◽  
Hydroxypropyl Cellulose ◽  
Biologically Active ◽  
Hydrodynamic Diameter ◽  
Temperature Dependent ◽  
Thermally Responsive ◽  
Derivatives Of ◽  
Average Hydrodynamic Diameter

Low water solubility frequently compromises the therapeutic efficacy of drugs and other biologically active molecules. Here, we report on coacervate polysaccharide nanoparticles (CPNs) that can transport and release a model hydrophobic drug, piroxicam, to the cells in response to changes in temperature. The proposed, temperature-responsive drug delivery system is based on ionic derivatives of natural polysaccharides—curdlan and hydroxypropyl cellulose. Curdlan was modified with trimethylammonium groups, while the anionic derivative of hydroxypropyl cellulose was obtained by the introduction of styrenesulfonate groups. Thermally responsive nanoparticles of spherical shape and average hydrodynamic diameter in the range of 250–300 nm were spontaneously formed in water from the obtained ionic polysaccharides as a result of the coacervation process. Their morphology was visualized using SEM and AFM. The size and the surface charge of the obtained objects could be tailored by adjusting the polycation/polyanion ratio. Piroxicam (PIX) was effectively entrapped inside the nanoparticles. The release profile of the drug from the CPNs-PIX was found to be temperature-dependent in the range relevant for biomedical applications.

Thermal gravimetric analysis of in-situ crosslinked nanocellulose whiskers • poly(methyl vinyl ether-co-maleic acid) • polyethylene glycol

TAPPI Journal ◽  
2011 ◽  
Vol 10 (4) ◽  
pp. 29-33
Author(s):  
LEE A. GOETZ ◽  
AJI P. MATHEW ◽  
KRISTIINA OKSMAN ◽  
ARTHUR J. RAGAUSKAS
Keyword(s):  
Thermal Stability ◽  
Polyethylene Glycol ◽  
Vinyl Ether ◽  
Thermal Gravimetric Analysis ◽  
Maleic Acid ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Methyl Vinyl ◽  
Methyl Vinyl Ether

The thermal stability and decomposition of in-situ crosslinked nanocellulose whiskers – poly(methyl vinyl ether-co-maleic acid) – polyethylene glycol formulations (PMVEMA-PEG), (25%, 50%, and 75% whiskers) – were investigated using thermal gravimetric analysis (TGA) methods. The thermal degradation behavior of the films varied according to the percent cellulose whiskers in each formulation. The presence of cellulose whiskers increased the thermal stability of the PMVEMA-PEG matrix.

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 Fabrication and characterization of hexadecyl acrylate cross-linked phase change microspheres

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 69-75
Author(s):  
Haoran Yun ◽  
Xingxiang Zhang
Keyword(s):  
Phase Change ◽  
Smooth Surface ◽  
Bone Conduction ◽  
Cross Linking ◽  
Gravimetric Analysis ◽  
Orthopedic Implant ◽  
Thermal Gravimetric ◽  
Fabrication And Characterization ◽  
Fast Release

AbstractMicrospheres with phase change properties were fabricated by polymerization of hexadecyl acrylate (HA) and different cross-linking agents. The samples were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA). The results show that, the samples that added cross-linking agents have a smooth surface and the latent heat of them is different. The experiments show that all of the cross-linked copolymer shells can be made into temperature controlled release microspheres. These materials can be potentially applied in the field of thermal energy storage. β-tricalcium phosphate was encapsulated in microspheres to obtain one with a fast release effect. It will effectively promote bone conduction when these microspheres were implanted into a bone defect. This microsphere can be used for orthopedic implant or coating of instrument in the future.

Trypsinolysis of Polyurethane Particles Based on Сyclodextrin with Encapsulated Moxifloxacin

2021 ◽  
Vol 37 (5) ◽  
pp. 72-79
Author(s):  
L.R. Yakupova ◽  
А.А. Skuredina ◽  
Е.V. Kudryashova
Keyword(s):  
Enzymatic Degradation ◽  
Dosage Forms ◽  
Oral Dosage ◽  
Hydrodynamic Diameter ◽  
Prolonged Action ◽  
Cyclodextrin Complexes ◽  
Acidic Media ◽  
Drug Molecules ◽  
Oral Dosage Forms ◽  
Average Hydrodynamic Diameter

Abstract-Moxifloxacin encapsulation in polymer cyclodextrin-based particles with an average hydrodynamic diameter of 150--200 nm has led to the formation of potential delivery systems with a degree of moxifloxacin inclusion of more than 80%. Cross-linking of the moxifloxacin-cyclodextrin complexes caused a pronounced slowdown in the release of the drug molecules in acidic media to less than 10% per day. In the presence of trypsin, the drug release was accelerated by 15--20% within 90 min. It was shown by Fourier-transform infrared spectroscopy that this acceleration was due to the partial enzymatic degradation of the urethane bonds of the polymer matrix near the surface of the particles. The results obtained are important for the development of highly effective oral dosage forms of prolonged action. Key words: fluoroquinolones, cyclodextrins, FTIR spectroscopy, trypsin

scholarly journals A simple and sensitive sensor for silver ions based on unmodified gold nanoparticles by using dynamic light scattering techniques

2017 ◽  
Vol 95 (12) ◽  
pp. 1267-1272 ◽  
Author(s):  
Zhiyou Xiao ◽  
Anjiang Tang ◽  
Hongsheng Huang ◽  
Ze Wang
Keyword(s):  
Gold Nanoparticles ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
High Sensitivity ◽  
Silver Ions ◽  
Hydrodynamic Diameter ◽  
Optimum Conditions ◽  
Sensitivity And Selectivity ◽  
Sensitive Sensor ◽  
Average Hydrodynamic Diameter

A simple and sensitive assay for Ag+ was developed with unmodified gold nanoparticles (AuNPs) by using dynamic light scattering techniques. Ag+ could induce the oligonucleotide (5′-ATC ACT ATA TCA TAT ACT CAT-3′) to change from a single-stranded structure to a double-stranded structure and desorb from the surface of AuNPs, which triggered the aggregation of AuNPs in the salt solution. The average hydrodynamic diameter of aggregated AuNPs could be detected by using dynamic light scattering techniques. Under the optimum conditions, the average hydrodynamic diameter of AuNPs is proportional to the concentration of Ag+ within the range of 13.3–100.0 nmol/L, with a detection limit of 3.2 nmol/L. The method is easy to operate and has low sample consumption, high sensitivity and selectivity.

Synthesis, Characterization and Application of Multi-Generations Hyperbranched Polyurethane Based on Isophorone Diisocyanate

2012 ◽  
Vol 554-556 ◽  
pp. 126-129 ◽  
Author(s):  
Shun Yin ◽  
Ning Sun ◽  
Chun Yun Feng ◽  
Zhi Mou Wu ◽  
Zhao Hua Xu ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Raw Materials ◽  
Degradation Mechanism ◽  
Resonance Spectroscopy ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Isophorone Diisocyanate ◽  
Scanning Calorimetry ◽  
Degradation Temperature ◽  
Hyperbranched Polyurethane

A series of different generation hyperbranched polyurethane(HBPU) was synthesized based on the raw materials of isophorone diisocyanate(IPDI) and diethanolamine(DEOA). Their structure, thermal degradation mechanism and glass transition temperature(Tg) were characterized by fourier transform infrared spectroscopy(FTIR), nuclear magnetic resonance spectroscopy(NMR), thermal gravimetric analysis(TGA) and differential scanning calorimetry(DSC). The results showed that: the yield of each generation HBPU was up to 90%, different generation HBPU had almost the same initial degradation temperature(about at 200°C) and they all had two decomposition platforms; with the increase of generation, Tg increased from 107.2°C to 132.1°C. The gloss and hardness of the HBPU coatings were significantly improved.

scholarly journals Polyurethane green composites for the treatment of boron present in the oil produced water

2020 ◽  
Author(s):  
Murtuza Ali Syed ◽  
Mohammed Al Sawafi ◽  
Feroz Shaik
Keyword(s):  
Produced Water ◽  
Chemical Properties ◽  
Gravimetric Analysis ◽  
Physical And Chemical Properties ◽  
Thermal Gravimetric ◽  
Boron Removal ◽  
Weight Losses ◽  
Chemical Solutions ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract Polyurethane (PU) based algae biocomposite is synthesized and tested for boron removal from oil produced water. The percentage of algae is varied in the biocomposite and its physical and chemical properties are evaluated. The surface morphology, crystalline structure, thermal stability is characterized using scanning electron microscope, fourier transform infrared spectroscopy and thermal gravimetric analysis. The density of synthesized PU/algae composites is in the range of 1.12 and 1.20 g/ml based on content of filler in the PU matrix. Weight losses of the tested specimens in various chemical solutions are less than 10%. The boron removal efficiency is in the range of 84–85%, depending upon the algae filler at pH 7.19.

Synthesis, Structure, and Characterization of La1−xBax (0 ≤ x ≤ 1)

1992 ◽  
Vol 271 ◽  
Author(s):  
Joseph E. Sunstrom ◽  
Susan M. Kauzlarich
Keyword(s):  
Magnetic Susceptibility ◽  
Powder Diffraction ◽  
Single Phase ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Temperature Dependent ◽  
X Ray ◽  
Early Transition Metal ◽  
Arc Melting

ABSTRACTThe compounds La1−xBaxTiO3 (0 ≤ × ≤ 1) have been prepared by arc melting stoichiometric amounts of LaTiO3 and BaTiO3. Single phase samples can be made for the entire stoichiometry range. The polycrystalline samples have been characterized by thermal gravimetric analysis, X-ray powder diffraction, and temperature dependent magnetic susceptibility. This series of compounds has been studied as a possible candidate for an early transition metal superconductor.

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