Design Study Of The Synthesis Of Novel Block Copolymers By Living Polymerization Methods

Several living polymerization methods were used to synthesis well-defined novelcopolymers. AB type diblock copolymer and ABA type Triblock copolymer wereprepared in nanoreactor of miniemulsion using reversible addition-fragmentation chaintransfer (RAFT) polymerization. The well-defined polymer brush of St and n-butylmethylacrylate (BMA) was synthesized by ATRP with the copolymer of Styrene(St) andp-chloromethylstyrene(CMSt) as macroinitiator, which was first synthesized by thenitroxide-mediated radical copolymerization of St and CMSt. These copolymers werecharacterized by means of GPC, IR, ~1H-NMR and DLS.(1) The chian transfer agent 2-cyanopro-2-yl dithiobenzoate(CPDB) was used to prepareAB type block copolymer. The influences of surfactant (sodium dodecyl sulfate, SDS),co-stabilizer (hexadecane, HD), ultrasonic period and reaction tempreture on theRAFT/miniemulsion polymerization were studied. GPC have confirmed that themolecular weights of the polymers produced were increased linearly with the conversionsof the monomer. And the molecular weight distributions index were in the range of 1.2 to1.35. The block copolymers formed in miniemulsion polymerization, poly(MAA-block-BA), were investigated.(2) Two RAFT chain transfer agents, dibenzyl trithiocarbonate (DBTTC) ands,s'-bis(2-hydroxyethyl-2'-isobutyrate) trithiocarbonate (BHEIBT), were used inminiemulsion polymerization of MMA and BA. The kinetics of RAFT miniemulsionpolymerization using trithiocarbonate as chain transfer agent was studied.(3) Polymer molecular brushes were synthesized by the combination of NMP and ATRP.The kinetics of two kinds of "living"/controlled polymerization were studied. Thecopolymers, P(St-co-CMS) and P(St-g-BMA), were characterized by means of GPC, IRand 'H-NMR, respectively. It indicated that the length and densty of the brush could becontrolled by living radiacal polymerization.