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Synthesis of Polyacrylonitrile Via Living/Controlled Radical Polymerization

Author: MaJing
Tutor: ChenHou
School: Lu Tung University
Course: Polymer Chemistry and Physics
Keywords: Activity controlled radical polymerization AGET ATRP Emulsion Polymerization SET-LRP AN
CLC: O632.62
Type: Master's thesis
Year: 2011
Downloads: 174
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Abstract


Polyacrylonitrile (PAN), is an important precursor of the polymer material, and has excellent physical and chemical properties. Narrow molecular weight distribution is an inevitable requirement for the synthesis of high-performance PAN. Activity controlled radical polymerization can be achieved the exact design of the polymer molecular structure, and is able to predict the molecular weight of the polymer, the synthesis of a narrow molecular weight distribution polymers, is therefore ideal for the preparation of a narrow molecular weight distribution of PAN polymerization techniques. In this thesis the electron transfer catalyst initiated atom transfer radical polymerization (AGET ATRP) technology and single-electron transfer living radical polymerization (SET-LRP) technique to synthesize a narrow molecular weight distribution of the PAN, and monomer acrylonitrile by gravimetric method were used conversion rate, measured by gel permeation chromatography (GPC) method for the determination of molecular weight and molecular weight distribution, the use of NMR spectroscopy (1H NMR) characterization of the structure of the PAN. AGET ATRP, acrylonitrile (AN) monomer, carbon tetrachloride (the CCl 4 ) as initiator, copper bromide (CuBr 2 ) / imino dicarboxylic acid (IDA) as a catalyst precursor, and ascorbic acid (VC) as the reducing agent, N, N-dimethyl formamide (DMF) as the solvent in a homogeneous system in the synthesis of a narrow molecular weight PAN Distribution. Kinetic experiments showed that the polymerization reaction is a kinetic reaction, the molecular weight of the PAN with the rate of increase of the monomer conversion increases linearly, and narrow molecular weight distribution, display activity controlled polymerization characteristics. The experiment also investigated the ligand, catalyst, initiator, reducing agent concentration and the polymerization temperature on the polymerization reaction. The study found that: When the the [AN: [CCl . 4 ]: [of CuBr 2 ]: [IDA]: [VC] = 200:1:1:2:0.75 when , the polymerization reaction controllability Preferably, the molecular weight distribution was 1.25; the polymerization reaction rate is accelerated as the polymerization temperature and the apparent activation enthalpy of polymerization reaction was 35.9 kJ / mol. AGET ATRP, AN as monomers, CCl 4 for the initiator, ferric chloride (FeCl 3 ) / lactic acid (LA) as a catalyst precursor, VC The reductant, DMF as solvent, in a homogeneous system in the synthesis of a narrow molecular weight PAN Distribution. Kinetic experiments showed that the polymerization reaction of the first order kinetics, the molecular weight of the PAN with the rate of increase of the monomer conversion increases linearly, and narrow molecular weight distribution, display activity controlled polymerization characteristics. The experiment also investigated the amount of ligand, initiator dosage, polymerization temperature and polymerization of different ligands. The study found that: When [AN]: [CCl 4 ]: [FeCl 3 ]: [LA]: [VC] = 200:1:1:2:0.75 , the polymerization reaction controllability Preferably, the molecular weight distribution was 1.20; polymerization reaction rate with the polymerization temperature and accelerated, the polymerization reaction of the apparent activation enthalpy of 32 kJ / mol. AGET ATRP, \tetramine (HMTA) as catalyst, VC as the reductant, polyoxyethylene lauryl ether (Brij35) as emulsifier, in an aqueous medium emulsion phase synthesis of a narrow molecular weight PAN Distribution. Kinetic experiments showed that the polymerization reaction is a kinetic reaction, the molecular weight of the PAN with the rate of increase of the monomer conversion increases linearly, and narrow molecular weight distribution, display activity controlled polymerization characteristics. The experiment also investigated the influence of the amount of the ligand, the polymerization temperature and monomer concentration in the polymerization reaction. The study found: When the molar ratio of [AN]: [CCl 4 ]: [of CuCl 2 ]: [HMTA]: [VC] = 200:2:1: 2:1.5, the polymerization reaction better controllability; the polymerization reaction rate is accelerated as the polymerization temperature, the polymerization reaction of the apparent activation enthalpy of 65 kJ / mol. SET-LRP, AN is the monomer, copper powder (Cu (0)) as the catalyst, CCl 4 for the initiator, HMTA as a ligand, a mixed solution of DMF or DMF, with water as solvent. at 25 ° C or 65 ° C in the heterogeneous system, a narrow molecular weight distribution of the synthesized PAN. Kinetic experiments showed that the polymerization in the two temperatures are a kinetic reaction, PAN molecular weight increases linearly with the increase in the conversion rate, narrow molecular weight distribution, active controlled radical polymerization characteristics. The experiment also investigated the amount of ligand, the amount of catalyst, triggering the dosage, and the influence of the solvent on the polymerization reaction. The study found that the monomer conversion rate with ligand HMTA concentration increases, when without HMTA when, due to the disproportionation of Cu (I) is weak, the polymerization reaction almost does not occur; increasing the catalytic system Cu (0) / HMTA the concentration, the polymerization reaction rate, adding the deactivators of CuCl 2 and the polymerization reaction controllability improved; monomer conversion versus CCl 4 concentration increases increases; hydro improve the polarity of a mixed solvent, thereby accelerating the polymerization reaction rate.

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CLC: > Mathematical sciences and chemical > Chemistry > Polymer chemistry ( polymer ) > Carbon - chain polymers > Nitrogen compounds in polymer > Nitrile polymer
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