Statistical Characteristics Of Multiple Self-Condensing Vinyl Polymerization Systems In Semi-Batch Mode

In recent decades,hyperbranched polymers(HPs)have been attracted intense attentions due to their unique structure and properties such as low viscosity and high solubility.By far,various self-condensing vinyl polymerization(SCVP)systems have been widely employed to prepare HPs in the fields of industry and chemical engineering,it is therefore of great importance to illustrate the detailed influence of the semi-batch mode on relevant properties of polymers.As is well known,the reaction rate of some living polymerizations is so fast that the heat released might be a potential hazard.The semi-batch mode in a polymerization can maintain a low concentration of reactants in the reactor to avoid the problem of exothermic.In addition to this advantage,the regulation of molecular weight(distribution)and composition of polymers can also be realized through the semi-batch mode.In this dissertation,a Monte Carlo simulation on the binary and ternary SCVP system under the semi-batch mode is presented,where reactants are composed of “monomers”(inimers for binary system while inimers and vinyl monomers for ternary system)and multi-functionality core initiators.Specifically,we presented the influence of feeding ways,vinyl conversions,feeding batches and other factors on the average polymeric quantities of HPs.In the research,the simulation algorithm of the system for semi-batch process can be given based on the differential kinetic equations of SCVP and then the variation of weight-average molecular weight and polydispersity index on the different feeding modes in SCVP system are obtained.It is expected to provide useful clues for the large-scale production of HPs.There are four chapters in the dissertation as following:Chapter one: Introduction.At the beginning,the background of HPs is introduced.Secondly,the self-condensing vinyl system of one-pot mothed has been outlined from experiments,theories and simulations,respectively.Thirdly,an explanation of several reactors in chemical operation has been given and emphasize the relevant semi-batch feeding research for further study.Chapter two: Monte Carlo Simulation on the Semi-batch Process in the Selfcondensing Vinyl Polymerization System in the Presence of Core Initiators.The semi-batch process of the SCVP in the presence of core initiators is investigated by the method of Monte Carlo simulation.An attempt is made to find the influence of different feeding ways on the weight-average molecular weight and polydispersity index of the resultant polymers.Specifically,we present several semi-batch modes,such as the case that core initiators are fed into the reactor at distinct conversions,and different feeding ways together with their details concerning the added molecules and conversions.Consequently,a significant effect of the semibatch process on the present system is found,which is expected to be useful in the large-scale production of HPs.Chapter three: Monte Carlo Simulation on the Ternary Self-condensing Vinyl Polymerization System with Semi-batch Process.A Monte Carlo simulation on the ternary SCVP system under the semi-batch mode is presented,where reactants are composed of comonomers(inimers and monomers)and multi-functionality core initiators.For the semibatch process in the system,we mainly consider the influence of three feeding ways on the average polymeric quantities(weight-average molecular weight and polydispersity index)of hyperbranched polymers,where core initiators and comonomers are fed into the reactor at different time(or equivalently,at different conversions of vinyl group).As expected,the semibatch process has a significant effect on the average properties of polymers,and therefore the feeding schedule can be predetermined to prepare polymers with desired properties.Chapter four: Summary.Several important conclusions of the simulation in the multiple SCVP system on the different semi-batch modes are given.Furthermore,some shortcomings are summarized in this dissertation and a brief overview of the development prospects in related fields is presented.