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N-isopropyl Acrylamide (n-isopropyl + acrylamide)

Distribution by Scientific Domains

Polymers and Materials Science	50%
Chemistry	50%

Selected Abstracts

Effect of molecular weight of poly(N -isopropyl acrylamide) temperature-sensitive flocculants on dewatering

AICHE JOURNAL, Issue 8 2009
Haihong Li
Abstract The influence of molecular weight (MW) and dose of Poly(N-isopropyl acrylamide) (PNIPAM) (temperature-sensitive flocculant) on sedimentation rate, sediment density, and supernatant clarity of silica suspensions was investigated. The addition of PNIPAM resulted in rapid sedimentation (T > critical solution temperature, CST) and low sediment moisture (T < CST). Higher MW polymers resulted in more effective flocculation and sediment consolidation. At 10 ppm, PNIPAM (3.6 million Da) produced 20 m/h settling rate and 48 vol % solids sediment density, whereas 0.23 million Da polymer produced 0.1 m/h settling rate. PNIPAM produces effective flocculation and consolidation by cycling the interparticle interactions between repulsion and attraction as temperature is cycled around the CST. The change in temperature produces a hydrophilic/hydrophobic transition of the polymer, influencing adsorption onto the surface and the inter-particle forces. Conventional polyacrylamide flocculants (not influenced by temperature), cannot be used to produce both rapid sedimentation and dense sediments. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

Metal Nanoparticle/Polymer Hybrid Particles: The Catalytic Activity of Metal Nanoparticles Formed on the Surface of Polymer Particles by UV-Irradiation

MACROMOLECULAR SYMPOSIA, Issue 1 2009
Toshiyuki Tamai
Abstract Summary: Polymer particles decorated with metal nanoparticles were prepared by UV-irradiation of polystyrene particles incorporating polymethylphenylsilane (PS/PMPS) and P[S- co -NIPAM]/PMPS particles (NIPAM: N-isopropyl acrylamide) in the presence of metal salts. The metal nanoparticle/polymer hybrid particles were used as a catalyst for the reduction of 4-nitrophenol with NaBH4. The Pd- and Ag-P(S- co -NIPAM)/PMPS hybrid particles had larger metal nanoparticles and the lower catalytic activity than those of Pd- and Ag-PS/PMPS, respectively. The surface functional group of the polymer particles affected the formation of the metal nanoparticles and their catalytic activity. [source]

Synthesis and characterization of dual-responsive micrometer-sized core-shell composite polymer particles

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3 2008
M. Ashraful Alam
Abstract Dual-responsive micrometer-sized core-shell composite polymer particles were prepared by dispersion polymerization followed by seeded copolymerization. Polystyrene (PS) particles prepared by dispersion polymerization were used as core particles. N-isopropyl acrylamide (NIPAM) and methacrylic acid (MAA) were used to induce dual-responsive that is thermo- and pH-responsive properties in the shell layer of composite polymer particles, prepared by seeded copolymerization with PS core particles. Temperature- and pH-dependent adsorption behaviors of some macromolecules on composite polymer particles indicate that produced composite polymer particles exhibit dual-responsive surface properties. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Control of Drug Release through the In Situ Assembly of Stimuli-Responsive Ordered Mesoporous Silica with Magnetic Particles

CHEMPHYSCHEM, Issue 17 2007
Shenmin Zhu Dr.
Abstract A site-selective controlled delivery system for controlled drug release is fabricated through the in situ assembly of stimuli-responsive ordered SBA-15 and magnetic particles. This approach is based on the formation of ordered mesoporous silica with magnetic particles formed from Fe(CO)5 via the surfactant-template sol-gel method and control of transport through polymerization of N-isopropyl acrylamide inside the pores. Hydrophobic Fe(CO)5 acts as a swelling agent as well as being the source of the magnetic particles. The obtained system demonstrates a high pore diameter (7.1 nm) and pore volume (0.41 cm3,g,1), which improves drug storage for relatively large molecules. Controlled drug release through the porous network is demonstrated by measuring the uptake and release of ibuprofen (IBU). The delivery system displays a high IBU storage capacity of 71.5 wt,%, which is almost twice as large as the highest value based on SBA-15 ever reported. In vitro testing of IBU loading and release exhibits a pronounced transition at around 32,°C, indicating a typical thermosensitive controlled release. [source]