The Micro- And Gradient Structures Of The Living Free Radical Copolymerization Products

In this thesis the sequence distribution of the Intermittent Living copolymerization products was studied in system.A new simulation model is proposed to deal with the statistical structures of the products of intermittent living copolymerizations. In an ILcP involving n kinds of monomers, the changes in states of a propagating chain end form a sequence, a Markov chain of 2n states, of which, n states correspond to n kinds of active species and the other n states correspond to n kinds of dormant species. When getting rid of the nominal structure related to dormancy in the chain, the remained chain corresponds to an average molecular chain. Computer simulations of dual ILcPs of five kinds are carried out under the stable condition. The results indicate that the existence of the dormancy affects neither the instant composition nor the instant sequence distributions of ILcP products. Both are identical with that of conventional copolymerizations.Another dynamic computer simulation program is developed to get the more convincing results. Chains of which the lengthes obey the Poisson distribution are produced by this effective model according to the changing probabilities which are calculated by the instant concentration of monomers. Through recording the number of reacted monomers and calculating the number of left ones, instant probabilities are got when the reactivity ratios and the initiator selectivities to monomers are considered.Statistic is carried on under certain conversions, so segment length distribution, average composition in polymers and various of triads are available and relations between the given parameters(reactivity ratios, initiator selectivity to monomers and initial feed composition, etc.) and the concentration of triads are achieved. Other results show that the segment length distribution is a novel one different from Flory distribution.Because the information of triads is enough to analysis the sequencedistribution of the copolymers, ATRcP of MMA and BA is carried on and the living characters are discussed.The carbon-13 NMR spectras of MMA-BA copolymers with feed composition fM equals 0.6524 are used to determine the triads concentration under different total monomer conversion. The trends of the cumulative triads concentration are compared with those of the dynamic simulation results, then the corresponding triad peak areas under lower conversion is subtracted from that under higher conversion according to certain rule. The results are considered as the instant triads concentration under the average conversion, this technology is used for the first time.The cognition on the characterization of the gradient copolymers is formed based on this work.