Patent ID: 11912806
Assignee: ZHEJIANG UNIVERSITY
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. A preparation method for a multiblock copolymer with narrow molecular weight distribution, wherein a structural general formula of the multiblock copolymer is R—Xm1-b-Ym2-b-(M1)n1-b-(M2)n2-b-(M3)n3 . . . -b-(Mj)nj-T, wherein R is an isopropyl acid group, acetoxy, 2-nitrile acetoxy or 2-amino acetoxy; in Xm1, X is a methacrylic acid monomer unit or an acrylic acid monomer unit, m1 is an average polymerization degree of X, and m1=10-40; in Ym2, Y is a styrene monomer unit or a methyl methacrylate monomer unit, m2 is an average polymerization degree of Y, and m2=3-10; M1, M2, M3 . . . Mj are comonomers of the copolymer, and are selected from styrene, methyl acrylate, ethyl acrylate, butyl acrylate, tert-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, tert-butyl methacrylate, n-butyl methacrylate, methyl 2-ethylhexyl acrylate, acrylonitrile, isoprene, butadiene, or a mixture of some monomers thereof, where j=5-20; n1, n2, n3 . . . nj are average polymerization degrees of respective blocks of the polymer, and n1, n2, n3 . . . =50-2000; T is an alkyl dithioester group or an alkyl trithioester group; and a final PDI of the polymer is less than 2.0,
wherein the preparation method comprises:
step 1 of dissolving 0.6-3 parts by weight of an amphiphilic macromolecule reversible addition-fragmentation chain transfer reagent in 20-50 parts by weight of water while stirring, subsequently adding 5-15 parts by weight of an M1 monomer, stirring and pre-emulsifying to obtain a mixture, and then adding the mixture into a reactor; heating the reactor to 30-80° C., keeping stirring, and introducing nitrogen to remove oxygen for more than 30 minutes; adding 0.001-0.05 parts by weight of an initiator into a reaction system; after reacting for 1-5 hours, adding 5-10 parts by weight of a sodium hydroxide aqueous solution containing 0.05-0.2 parts by weight of sodium hydroxide, and continuing to react for 0.2-0.5 hour to obtain a block copolymer R-Xm1-b-Ym2-b-(M1)n1-T, in a form of particles stably dispersed in water to form a latex;
step 2 of after the reaction in the step 1 is finished, adding 5-30 parts by weight of an M2 monomer and 20-100 parts by weight of water, keeping a reaction temperature unchanged or adjusting the reaction temperature within a range of 30-80° C., then adding 0.001-0.05 part by weight of the initiator, and reacting for 1-10 hours to obtain a block copolymer R—Xm1-b-Ym2-b-(M1)n1-b-(M2)n2-b-T, in the form of particles stably dispersed in water to form a latex;
step 3 of after the reaction in the step 2 is finished, sequentially adding 5-30 parts by weight of M3, M4 . . . Mj monomers and 20-100 parts by weight of water, keeping the reaction temperature unchanged or adjusting the reaction temperature within a range of 30-80° C., then adding 0.001-0.05 part by weight of the initiator, and reacting for 1-15 hours in each reaction segment to obtain a j-block copolymer R—Xm1-b-Ym2-b-(M1)n1-b-(M2)n2-b-(Mj)nj-T, in a form of particles stably dispersed in water to form a latex; and
step 4 of demulsifying, cleaning and drying the obtained latex to finally obtain white or yellowish polymer powder or particles,
wherein when the M1, M2 . . . Mj monomers are styrene, methyl methacrylate, ethyl methacrylate, tert-butyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, acrylonitrile, or a mixture of some monomers thereof, the reaction temperature in step 2 or step 3 is adjusted to 60-80° C.; and when the M1, M2 . . . Mj monomers are methyl acrylate, ethyl acrylate, n-butyl acrylate, tert-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, isoprene butadiene or a mixture of some monomers thereof, the reaction temperature in step 2 or step 3 is adjusted to 30-60° C.