Study Of Atom Transfer Radical Copolymerization Of Acrylic Monomers

Copolymerization of methyl methacrylate(MMA) and 2-hydroxyethyl methacrylate (HEMA) was studied in emulsion by atom transfer radical polymerization (ATRP). The emulsion atom transfer radical copolymerization of MMA and HEMA was carried out with Tween-80 as surfactant ,benzyl bromide as an initiator and CuBr/CuBr2/bpy(2,2'-bipyridine)(or dNbpy (4,4'-dinonyl-2,2'-bipyridine) or phen (o-phenanthroline) or PMDETA (N , N ', N ', N" ,N"-pentamethyldiethylenetriamine)) as a catalyst system, and its influencing factors was discussed, and the best formula was obtained by experiments, and the copolymer of MMA and HEMA that made by the formula is tested by GPC, IR, NMR and hydroxyl value analysis.ATRP of two different ways of the added reactants was compared, the effects of ways of the added reactants was analyzed by total conversion of monomer. It is beneficial to polymerization that the oil-soluble initiator was added preceding to catalyst system and emulsion is precasted and the reaction occurred by catalyst system, because the initiator is easy into micelle. If the other reactants was added and emulsion is precasted and the reaction occurred by the initiator, then possibly initiator occurred more side-reaction, polymerization may be difficult or slow to carry out.When the reaction temperature is changed at different experiments, the polymerization rate increases depending on temperature, but the linear relationships of ln([M]0/[M])～t in polymerization is impacted. When proper ligand is used, the linear relationships of ln([M]0/[M])～t is better, the intrinsic viscosity of the polymer solution increases depending on monomer conversion, and the controlled characteristic is better. Polymerization can occur at wider temperature range when dNbpy is as ligand, and the reactions have the controlled characteristic; just the oil-soluble ligand is more beneficial to control the emulsion ATRP.When the ligand proportion increased in experiment, the initiator initiates easily, and polymerization speeds up. Conversely, proportion of CuBr2 in catalyst is increased, the reaction rate gets slower significantly, meanwhile the reaction controlled characteristics may be changed.Amount of emulsifier effects polymerization rate and latex stability. To increase amount of emulsifier, the reaction rate shows increasing trend, but amount of emulsifier has different effects of the reaction rate in ATRP and conventional emulsion polymerization, and the reaction rate is not proportional to 0.6 power of emulsifier concentration. The more emulsifier concentration benefits to latex stability.The proper initiation system of monomer([C6H5CH2Br]0/[CuBr]0/[CuBr2]0/ [dNbpy]0 :1/0.95/0.05/2), suitable amount of emulsifier (Tween-80/([MMA]0+[HEMA]0 =18.1%) and proper reaction temperature (30℃)was obtained by the above experiment. The copolymer of MMA and HEMA that made by the conditions was tested by GPC, Mn=36790, PDI=1.38; Curve of ln([M]0/[M])～t and Mn～monomer conversion shows linear relationships. These shows significantly controlled characteristics of polymerization. The differential thermal analysis (DTA) of the reaction production don't contain peak of homopolymer of MMA or HEMA . The proportion of MMA and HEMA in sample of the different time has small difference by IR, NMR and hydroxyl value analysis, it indicates that reactivity ratio of MMA and HEMA has small difference and hydroxyl has a better uniform distribution.