| Free radical polymerization is a chemical reaction of the growing radical initating the monomer. It has already become a significant technique for producing a wide variety of polymeric products in industry. At present, the industrial polymers obtained by free radical polymerization has accounted for about 70% of the total production. The chain initiation process controlled by radical has directly effect on the reaction rate and the performance of polymeric materials. In this paper, we explored a novel initiator system, consisted of haloalkanes and amines, to initiate the polymerization of methyl methacrylate(MMA), methyl acrylate(MA)and styrene(St). The major contents and achievements of this paper are as follows:1. In this paper, we had firstly found that the free radical polymerizations of MA, MMA and St could be initiated by a series of hydrocarbons(halogenated nitriles)/amines, including EBi B/PMDETA, DAN/PMDETA, ECA/PMDETA, ECP/PMDETA, EBi B/ Me6 TREN, EBi B/HMTA, EBi B/TEOA from room temperature to 100 ℃. The initiation rate was designed in a wide range with the change of initiation system and reaction temperature.2.The polymerization kinetics of MMA initiated by EBi B/PMDETA, EBi B/Me6 TREN and EBP/PMDETA were investigated. The initiation efficiency and activity of EBi B/PMDETA were found to be higher than EBi B/Me6 TREN and EBP/PMDETA. The polymerization rate of MMA obtained by EBi B/PMDETA was significantly accelerated with the increase of the reaction temperature and the apparent activation energy initiation was 75.7 k J/mol. Though the polymerization rate of MMA was promoted remarkably in the presence of Na I、KI and glucide, these additives also reduced the efficiency of the novel initiator. Acetyl phenylhydrazine(APH) could improve the initiation efficiency of EBi B/PMDETA and obtained a lower molecular weight polymer at the same concentration of initiator and similar reaction conditions.3. A lot of initiator systems(EBi B/TEA, EBP/Me6 TREN and et al.) had been explored for free radical polymerization of MA. The results showed EBP/Me6 TREN system performsed high activity and efficiency. The number-average molecular weight of the polymer did not changed significantly with the increase of the monomer conversion which indicated the polymerization is a conventional radical polymerization.4. This paper explored the mechanism of radical generation in the experimental process. No polymer was obtained in presence of DPPH, which is a highly effective free radical trapper. The polymerization initiated by this system can inferred to be a free radical mechanism. A curcumin-based initiator(Br-Curcumin-Br) was synthesized by acylation reaction of curcumin with 2-bromoisobutyryl bromide. The Br-Curcumin-Br fragment was existed in the PMMA obtained by Br-Curcumin-Br/PMDETA which revealed by UV-vis of the polymer. Additionally, the 1H-NMR spectra of PMA solutions obtained by EBP/Me6 TREN initiator system revealed that the ethyl 2-phenylacetate(EP·) radical from haloalkane moieties was the end groups of polymer. The radical was further analyzed by electron spin resonance spin-trapping technique(ESR-ST). |
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