Font Size: a A A

Preparation Of Molecularly PANI Nanoparticles And Its Application In Electrochemical Sensors

Posted on:2016-09-04Degree:MasterType:Thesis
Country:ChinaCandidate:J SunFull Text:PDF
GTID:2308330464461766Subject:Materials Science and Engineering
Abstract/Summary:PDF Full Text Request
Molecularly imprinted polymers(MIPs) exhibit high selectivity and affinity to the template molecule, due to the presence of recognition cavities that only match the shape, size and functional groups of the template molecule. Combining MIPs with electrode, the molecularly imprinted sensors with high selectivity and sensitivity could be fabricated. However, the classical MIPs are normally electrical insulating polymers, which thus form a serious barrier for electron transfer and pose severe limitations on the efficiency of the signal transduction. On the other hand, nano-sized MIPs possess unique characteristics of small dimension with extremely high surface-to-volume ratio, hence most template molecules are situated at or close to the surface materials, which leads to more complete removal of templates, higher binging capacity, faster binding kinetics. Combining the merits of conducting polymers with nano-sized MIPs, highly sensitive and selective electrochemical sensors could be fabricated.In this paper, combining the theories of self-assembly, nanotechnology and molecularly imprinted technique, novel PANI nanoparticles with molecularly imprinting were prepared; and MIP sensors with high selectivity and sensitivity were constructed by immobilizing the molecularly imprinted PANI nanoparticles on the electrode. The detailed experiments are described as follows:(1) The preparation of imprinted PANI nanoparticles by co-assembly of amphiphilic copolymer and dedoped PANI and its application in MIP sensor. The amphiphilic copolymer was synthesized via free radical polymerization using acrylic acid(AA), styrene(St) and vinyl pyrrolidone(VP)(P(AA-co-VP-co-St), abbreviated as PAVS). Complexes of copolymer PAVS and dedoped PANI could self-assemble in aqueous solution to form a water-dispersible PANI nanoparticles by electrostatic interaction. The role of copolymer is to enhance the solubility of PANI in aqueous solution and to control the morphology and size of PANI nanoparticles. Paracetamol(PCT) was chosen as the imprinting molecule and added to the co-assembly system of PAVS and PANI, leading to the preparation of molecularly imprinted PANI nanoparticles following the same process. After immobilization on an Au electrode and extraction of PCT, the imprinted PANI sensor with recognition sites for PCT was prepared, and the properties of the sensor were investigated. The resulted sensor showed good response and selectivity towards PCT. In addition, a wide linear range from 5 μmol/L to 1000 μmol/L and low detection limit of 1.0×10-7 mol/L for PCT detection was demonstrated based on this sensor.(2) The preparation of imprinted PANI nanoparticles using copolymer micelle as soft templates and its application in MIP sensor. Firstly, P(AMPS-co-St) copolymer was synthesized by the copolymerization of styrene(St) and 2-acrylamido-2-methyl-1-propanesulfonic acid(AMPS), which easily self-assembled into polymeric micelle in aqueous solution. The copolymer micelle was then used both as a template and a dopant for the in situ polymerization of aniline, leading to a narrow size distribution of the water-dispersible PANI nanoparticles. The imprinting molecule PCT was added together with aniline monomer into the micelle solution, leading to PCT imprinted PANI nanoparticles. After immobilization on an Au electrode and extraction of the PCT molecule, the imprinted PANI sensor with specific recognition sites complementary in shape and size to PCT was prepared. Contrast to the imprinted sensor above, the new prepared imprinted PANI sensor showed better response and selectivity towards PCT. The wider linear range from 0.4 μmol/L to 1000 μmol/L and lower detection limit of 5.0×10-8 mol/L for paracetamol detection was demonstrated based on this sensor.
Keywords/Search Tags:amphiphilic copolymer, self-assembly, PANI, molecular imprinting, electrochemical sensor
PDF Full Text Request
Related items