China
Africa
Explore chapters and articles related to this topic
Materials and Synthesis of pH-Responsive Membranes
Published in Randeep Singh, Piyal Mondal, Mihir Kumar Purkait, pH-Responsive Membranes, 2021
Randeep Singh, Piyal Mondal, Mihir Kumar Purkait
The temperature-induced grafting method is a simple and easy-to-use method for the grafting of pH-responsive groups or polymers over a membrane surface. The basic requirement of this method is a chemical initiator or a cleavage agent, such as Azobisisobutyronitrile (AIBN). Generally, the polymerization is performed in a heterogeneous polymer-monomer reaction system in a solvent, such as water, toluene, ethanol, and others. Later, this prepared pH-responsive polymer is used to synthesize PRM. Both the “graft to” and “graft from” routes can be used. Sinha et al. [3] used this method for the preparation of pH-responsive flat sheet polysulfone ultrafiltration membranes. In this study, the copolymer poly(acrylic acid)-co-poly(ethylene glycol methyl ether methacrylate) (poly(AA-co-PEGMA)) was prepared by precipitation polymerization in toluene using AIBN as the chemical initiator. The reaction components were taken in a round-bottom three-neck flask having a condenser and an inlet and outlet for nitrogen gas. The reaction was carried out in an inert atmosphere in a boiling oil bath for ~2 h. On completion of the reaction, the reaction mixture was brought to room temperature by cooling and then vacuum filtered. Lastly, the final product was heat dried at 50°C for 4 days. The presence of pH-responsive groups in the copolymer was checked by using Fourier transform infrared spectroscopy (FTIR). Later, this pH-responsive copolymer was blended in the polysulfone membranes to impart pH responsiveness and tested for pH response with pH-based bovine serum albumin rejections.
Molecular-Imprinting-Based Sensors
Published in Banshi Dhar Gupta, Anand Mohan Shrivastav, Sruthi Prasood Usha, Optical Sensors for Biomedical Diagnostics and Environmental Monitoring, 2017
Banshi Dhar Gupta, Anand Mohan Shrivastav, Sruthi Prasood Usha
Polymerization initiators: Molecular imprinting is broadly performed by free radical polymerization, electropolymerization, and photopolymerization methods. The rate of free radical polymerization is strongly affected by the initiator properties (Lanza et al. 2001). 2-Azobisisobutyronitrile (AIBN) is the mostly used initiator for polymerization. This is because of thermal decomposition of AIBN which results in the formation of two isobutyronitrile radicals, which initiate the polymerization process. For free radical polymerization, mostly azo-group compounds are used as the initiators. Figure 6.2 shows the few initiators used for the synthesis of the polymerization. The removal of oxygen bubbles from prepolymerized solution is also important before starting the polymerization process because the presence of oxygen molecules may lead to the instability of the final product. The oxygen removal is usually performed by keeping the prepolymerization complex in an inert gas atmosphere such as nitrogen or argon.
Thermal decomposition kinetics of synthesized poly(N-isopropylacrylamide) and Fe3O4 coated nanocomposite: Evaluation of calculated activation energy by RSM
Published in Petroleum Science and Technology, 2023
Ersin Pekdemir, Ercan Aydoğmuş, Hasan Arslanoğlu
PNIPA was synthesized by free-radical polymerization method using azobisisobutyronitrile (AIBN) initiator (Vihola et al. 2005). Firstly, 27 mmol (3.0 gram) NIPA monomer was placed in the polymer tube and dissolved in 10 mL of C4H8O2. A solution of AIBN (0.027 mmol) prepared in 1 mL C4H8O2 was added to the monomer solution. Argon (Ar) gases were passed through the solution for 15 min and mixed under room conditions for a while and then the temperature was increased to 70 °C. The reaction was stirred at this temperature for 18 h. At the end of the reaction, the temperature of the solution was decreased to room temperature and precipitated in cold diethyl ether. The obtained polymer was dried for 24 hours in a vacuum oven at 40 °C. Figure 1 clearly shows the schematic diagram of PNIPA synthesized from NIPA.
Droplet size controllable fabrication of Pickering emulsion stabilized by soy protein isolate-carbon nanotubes/carboxymethyl cellulose sodium
Published in Soft Materials, 2022
Xiang Li, Fantian Wang, Jiaxin Ma, Haibiao Zhu, Rui Yang, Hirofumi Tanaka, Xiaoming Ma, Liu Hong
In order to disperse CNTs in aqueous environment, 30 mg CNTs were mixed with 10 mg CMC-Na in 10 mL deionized water and sonicated for 90 min. SPI powder (protein concentration c = 0.5%, w/v) and various organic solvents including paraffin oil, toluene, hexane, and olive oil of different oil fraction (ϕ) were consequently mixed in the CNT suspension. The mixture was homogenized for another 2 min at a speed of 15,000 rpm (DH-S10, Lawson Scientific) so as to form a black sticky liquid as Pickering emulsion. The pH value of the emulsion was further adjusted from the original 7.0 to different values (3.0, 5.0, 9.0, and 11.0) via the blending of 1 M hydrochloric acid and 1 M sodium hydroxide and confirmed by pH meter (Sartorius PB-10). The zeta potential of emulsion particles was determined using Zetasizer 2000 (Malvern Instruments). The emulsion droplet morphology and size were characterized by super-high magnification lens zoom 3D microscope (VHX-1000 C, Keyence). For the observation of transmission electron microscope (TEM), 2 mL styrene solution of azobisisobutyronitrile (AIBN, 1%) was used as organic solvent, mixed with above CNT suspension and heated at 70℃ for 24 h so as to coat SPI-CNTs/CMC-Na layer on the interface of synthesized polystyrene droplets.
Improvement of mechanical properties of elastic materials by chemical methods
Published in Science and Technology of Advanced Materials, 2020
Yukikazu Takeoka, Sizhe Liu, Fumio Asai
A polyrotaxane crosslinking agent (HPR-C) (Figure 16(a)) obtained from a derivative (HPR) synthesized by adding a hydroxypropyl chain to the α-CD of PR was used. Furthermore, diethylene glycol methyl ether methacrylate (MEO2MA) (Figure 16(b)), which is in a liquid state at room temperature for both the monomer and the polymer, was used as the monomer. MEO2MA and HPR-C were dissolved in dimethylsulfoxide (DMSO) together with the radical initiator azobisisobutyronitrile (AIBN), and a gel swollen with DMSO was obtained by thermal polymerization. Then, unreacted materials and DMSO were washed with methanol, and methanol was distilled off to obtain an elastomer composed of MEO2MA and HPR-C (Figure 16(b)). For comparison, an elastomer composed of MEO2MA using ethylene glycol methyl ether methacrylate (EGDMA) as a typical cross-linking agent was also synthesized (Figure 16(b)).