Study On Preparation And Performance Of Acrylate Block Copolymer By RAFT Polymerization

Polypropylene (PP) plastics is widely used in electronics, toys, automobile and other industries because of its characteristic of easy processing, non-toxic and tasteless, low density, low cost, good chemical stability and so on. However, the problem thatcoatings are difficult to adhere to the substrate surface of polypropylene surface restricts the application of PP. Poly(isobornyl acrylate) has good adhesion to PP substrate because of the rubust dispersion force between poly(isobornyl acrylate) and polypropylene. Besides, acrylate copolymershave good compatibility with conventional UV resin. Reversible addition-fragmentation chain transfer (RAFT) living free radical polymerization is often used to prepare the block copolymer because of its advantage of suitable for wide range of monomers, having good molecular design ability and convenient conditions to implement, etc. In this paper, two kinds of RAFT agent were synthezied by phase transfer catalyzed (PTC) reaction, and thentwo kinds of acrylate block copolymers were also synthesized by RAFT method. The synthesized products are characterized and the polymerization kineticswas investigated. Finally, the synthesized block copolymers, in which one chain segment has good adhesion to PP substrate with the function of poly(isobornyl acrylate) and another chain segment has good compatibility with UV resin, are added to the coatings formula to study their effect on the adhesion property of raw PP substrate by mechanical properties test. The main research work and conclusions are as follows:1. Synthesis and characterization of RAFT agentTwo kinds of RAFT agent were synthesized:Using carbon disulfide, acetone, chloroform, sodium hydroxide as raw material and tetrabutylammonium hydrogen sulfate as catalyst, RAFT agent S,S’-bis(R,R’-dimethyl-R"-acetic acid)-trithiocarbonate(BDAATB) was synthezied. Using 1-Dodecanethiol, acetone, carbon disulfide, chloroform,sodium hydroxide as raw materials and tricaprylylmethylammonium chloride as catalyst, RAFT agent S-1-Dodecyl-S’-(R,R’-dimethyl-R"-acetic acid)-trithiocarbonate(DDAATB) was synthezied. The component and structure of two kinds of RAFT agent are characterized by FTIR,’H NMR, mass spectrum and elemental analysis.2. Preparation of acrylate block copolymers by RAFT polymerization.Poly(isobornyl acrylate) was prepared by using BDAATB as the RAFT agent, then the poly(isobornyl acrylate) block polymethyl methacrylate copolymer was prepared using poly(isobornyl acrylate) as the macro-RAFT agent. Polyacrylic acid is prepared by using DDAATB as the RAFT agent, and then polyacrylic acid block poly(isobornyl acrylate) was prepared using polyacrylic acid as the macro-RAFT agent. Finally, the products are characterized by FTIR,1H NMR and GPC.3. Studying on polymerization kineticsThe polymerization behavior of poly(isobornyl acrylate) and polyacrylic acid homopolymer, including reaction temperature, concentration ratio of monomer with RAFT agent, concentration ratio of monomer with initiator, were studied andthe effect of the chain length of the marco-RAFT agent on the preparation of block copolymers are also discussed.4. The effect of block copolymer on the adhesion property of PP substrate.The block copolymerprepared as the adhesion promoter was added to the coatings formula and paintted directly to the PP substrate. The peel strength of different mass fraction of block copolymer as the adhesion promotor was tested and comparasion with CPP was made.