Poly(methyl) crylic acid-b-styrene-b-styrene/acrylonitrile) segmented copolymer latex and preparation method thereof

Abstract

The invention discloses poly(methyl) crylic acid-b-styrene-b-styrene / acrylonitrile) segmented copolymer latex and a preparation method thereof. An emulsion polymerization system is adopted, a reversible addition fragmentation chain transfer free radical polymerization technique is adopted, and a styrene and acrylonitrile monomer is added so as to prepare the copolymer latex consisting of different monomers. The preparation method is simple in process and equipment and environmental-friendly and energy-saving; due to adoption of an amphipathy macromolecule reversible addition fragmentation chain transfer reagent which has functions of both a chain transfer reagent and an emulsion agent, both good control on polymerization of the monomers is achieved, and the use of a conventional emulsion agent is avoided; the reaction is free of polymerization blocking period, the reaction speed is fast, the final conversion rate is high, the latex particle is stably increased in the process, a product is wide in molecular weight range, wide in monomer consisting range and good in application prospect in the fields such as transparent structural materials and polymer alloy commixing components.

Description

technical field [0001] The invention relates to a block copolymer material, in particular to a reversible addition-fragmentation chain transfer emulsion polymerization to prepare poly((meth)acrylic acid-b-styrene-b-styrene / acrylonitrile) block copolymer latex Methods. Background technique [0002] Styrene / acrylonitrile copolymer has a series of excellent properties, such as solvent resistance, heat resistance, transparency and good processability, etc. It is mainly used in transparent structural materials or blending components of polymer alloys. Traditional styrene / acrylonitrile copolymers are obtained by free radical polymerization using solution method, suspension method or emulsion method. Compared with other polymerization methods, emulsion polymerization uses water as the medium, which is conducive to heat transfer, environmental protection and safety, and emulsion viscosity Low, convenient for pipeline transportation and continuous production; molecular chain growth ...

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Problems solved by technology

[0004] However, the RAFT emulsion polymerization system has problems such as colloidal instability, slow polymerization and inhibition, wide molecular weight distribution, and obvious deviation between actual molecular weight and theoretical molecular weight.

Gilbert et al. used polyacrylic acid-polybutylacrylate amphiphilic macromolecular reversible addition fragmentation chain transfer reagents to carry out RAFT semi-continuous emulsion polymerization of styrene with starvation method, which solved the problem of emulsion instability, but the process was complicated and The deviation between the actual molecular weight and the theoretical molecular weight is large, and no block copolymer can be prepared; Charleux et al. used the reversible addition and fragmentation chain transfer reagent containing polyethylene oxide macromolecules to carry out batch emulsion polymerization of styrene, and the reaction time was 22.7 hours. The final conversion rate is only 66.7%

The amphiphilic macromolecular reversible addition-fragmentation chain transfer reagents used in the styrene batch emulsion polymerization system reported in other literatures, such as polystyrene-polyvinylphenyltriethylammonium chloride diblock reversible addition-fragmentation Chain transfer reagents, polydiethylmethacrylate ethylamine monoblock reversible addition fragmentation chain transfer reagents, polyethylene oxide-polydiethylmethacrylate ethylamine diblock reversible addition fragmentation chain transfer reagents, etc. Neither failed to exhibit any controllability over the molecular weight

The main reason for the failure of the styrene RAFT emulsion polymerization reported in the literature is that the amphiphilic macromolecular reversible addition fragmentation chain transfer reagent used is improperly designed in the proportion of the length of the hydrophilic and lipophilic segments, and must be neutralized by adding alkali to dissolve in water. The reaction results show that the reaction polymerization inhibition period is long, the reaction speed is slow and the final conversion rate is low, the molecular weight of the product is out of control and the molecular weight distribution is wide, and the emulsion system is unstable, so high molecular weight polymers and block copolymers cannot be synthesized well.

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