The Experiments And Simulation For The Cumulated Composition And Sequence Distribution Of Gradient Polymer Latex Particles

Polymer latex particles with special structure have been widely investigated for its uniqueapplications. Power feed technique is one of the major tools used in the production ofnonuniform latex particles, while the quantitative control theory for the process is still underdevelopment. In this paper, on the basis of traditional free radical polymerization, latex particleswith gradient structure were firstly synthesized by use of power feed technology. Aftermathematical analysis of the accumulated composition and sequential distribution, simulationof the reaction process is achievable which is obviously important for the industrial production.Reactivity ratios are crucial for the control of accumulated composition and sequentialdistribution in the free radical polymerization. The apparent reactivity ratios of MMA and BAin emulsion polymerization were measured by use of1H-NMR. Various methods have beenused to obtain monomer reactivity ratios, which were input arguments for the established model.The calculated values for MMA and BA are2.660.05and0.350.02, respectively, beingdifferent from the corresponding2.28and0.40in solution polymerization. The departure canbe interpreted by the radical entry mechanism developed by Maxwell-Morrison. The averagesequence length of MMA units and BA units are3.66and1.33, respectively, illustrating thatMMA are more liable to self-polymerization.On the suppose of Mayo-Lewis equation and first-order Markov propagation, by drop-stepanalysis of the power feed, that is to divide the total procedure into enormous instantaneousbatch reactor, the corresponding cumulated composition and sequence distribution equation canbe deduced with reactivity ratios and conversion function as the parameters. The simulationresults are in good correspondence with the experimental data by1H-NMR and13C-NMR.The reactivity ratios by different methods made little influence on the simulation result.The PMMA/PBA nano particles were synthesized by use of SDS/Pentanol with mass ratioat7/1as surfactant and co-surfactant. Core-shell structure of the particles was characterized byTEM and1H-NMR.It was found by the experiments that the maximum of achievable solidcontent for the system was39.4%and the required minimum surfactant accounted for6.3%of monomer mass. The size of nano particles showed a downward trend when increasing the usageof surfactants?while an inverse trend was observed when improving the usage of core monomer.Especially,1.3%surfactant usage was found to be effective in synthesizing core-shell particles,avoiding the formation of new particles in second stage.