Study On Catalyst Systems For ATRP Of Methyl Methacrylate

In this thesis, iron-mediated initiators for continuous activator regeneration atomtransfer radical polymerization （ICAR ATRP） of methyl methacrylate （MMA） were carriedout successfully and higher catalyst activity was observed in this catalyst system, whichfacilitates wider applications of iron catalyst. Besides, soap-free miniemulsionpolymerization of MMA was successfully carried out via a reverse ATRP technique using akind of organic copper salt as the catalyst, which helps to establish a facile method for thesynthesis of "living" soap-free miniemulsion. The works can be summarized as follows:（1） System I: Iron-mediated ICAR ATRP of MMA. The bifunctional initiator1,4-（2-bromo-2-methylpropionato） benzene （BMPB2） was firstly synthesized via reactionbetween1,4-dihydroxybenzene and2-bromoisobutyryl bromide. Then, the ICAR ATRP ofMMA was investigated using FeCl₃·6H₂O as the catalyst, triphenylphosphine （PPh₃） as theligand, BMPB₂as the initiator, and AIBN as thermal radical initiator. Effects of reactiontemperature, catalyst concentration and AIBN concentration on polymerization wereinvestigated. These results showed the first-order polymerization kinetics, and themolecular weight （Mn,GPC） values of the polymers increased linearly with monomerconversion with narrow molecular weight distribution （M_w/M_n） values. The chain end ofthe PMMA was analyzed by1H NMR spectroscopy. Successful chain extension reactionfurther proved the livingness of the obtained PMMA.（2） System II: soap-free miniemulsion polymerization of MMA by reverse ATRP. Inthis work, soap-free miniemulsion polymerization of MMA was successfully carried outvia a reverse ATRP technique, using a water-soluble potassium persulfate （KPS） or2,2′-azobis（2-methylpropionamidine） dihydrochloride （V-50） both as the initiator and thestabilizer; and using an oil-soluble N,N-n-butyldithiocarbamate copper （Cu（S₂CN（C₄H₉）₂）₂）as the catalyst without adding any additional ligand. Effects of the monomer ratio, catalyst concentration and reaction temperature on polymerization were investigated. All thepolymerization results showed the "controlled"/living radical polymerizationcharacteristics of ATRP in this novel miniemulsion system. The morphologies and particlesize distributions of the obtained latexes from soap-free emulsion polymerization wereobserved by field-emitting scanning electron microscopy （FE-SEM） and dynamic lightscattering （DLS）, respectively. The nucleation mechanism was proposed. The¹H NMR and¹³C NMR spectroscopy indicated that the chain ends of the obtained PMMA attached anultraviolet light sensitive group-S-C（=S）-N（C₄H₉）₂from the catalyst Cu（S₂CN（C₄H₉）₂）₂.Successful chain extension of MMA and St using PMMA as the macroinitiator underUV-light irradiation at room temperature further proved the "living"/controlled radicalpolymerization characteristics of this novel system.