Preparation method of double-mercapto-terminal polymer

Abstract

The invention relates to a preparation method of a double-mercapto-terminal polymer. The preparation method comprises the following steps: reacting a mercapto protection reagent with halomercaptan in a polar solvent according to a molar ratio of 1:1 at -5-5DEG C for 24h, extracting with a weakly-polar solvent, taking the obtained supernatant, evaporating in a rotary evaporator to remove the solvents, and carrying out column chromatography separation to obtain an initiator intermediate, wherein a catalyst used in the above reaction is imidazole, pyrimidine or pyridine; reacting the initiator intermediate with metallic lithium in a non-polar solvent at 30-70DEG C to obtain an initiator, wherein the molar ratio of the initiator intermediate to the metallic lithium is 1:6.7; sequentially adding a solvent, the initiator, a monomer and a structure adjustment agent to a reaction kettle, and reacting at 0-60DEG C to obtain an active polymer; adding a terminating reagent to the polymer, reacting, and adding methanol to terminate; and acidifying the terminated polymer by an inorganic acid to obtain the double-mercapto-terminal polymer. The obtained polymer has the advantages of narrow molecular weight distribution, controllable molecular weight, adjustable chain microstructure, and high functionalization efficiency.

Description

technical field [0001] The invention belongs to the field of polymer preparation with terminal functional groups, and relates to a preparation method of a double-ended mercapto polymer, which uses a silane-protected mercapto initiator to initiate monomer polymerization to prepare the double-ended mercapto polymer. Background technique [0002] Terminal functional group polymer is a polymer with active groups at the end of the main chain of the molecule. Low molecular weight double-ended mercapto polybutadiene or polyisoprene is a kind of liquid rubber. Due to its special active end group And the liquid performance at room temperature makes it have special uses that solid rubber can't compare with. For example, double-ended mercapto polybutadiene has been successfully used in the bonding of caulking materials, sealing materials and solid rocket propellants due to its special mercapto groups that make it cure faster than double-ended hydroxyl polybutadiene at room temperature....

AI Technical Summary

Problems solved by technology

Although the steps of the double-terminated mercapto polymer prepared by the end group conversion method are simple, due to the problem of low conversion rate in the end group conversion process, there are still substances with other functional groups in the obtained terminal mercapto polymer.

On the other hand, since the viscosity of the liquid terminal functional group polymer will increase during the re-transformation of the terminal group, its application performance will be affected.

[0005] The currently reported anionic polymerization method of double-terminated mercapto polymers is mainly the polymerization of monomers initiated by organic alkali metal initiators, such as the preparation of mercapto-terminated polymers mentioned in USP3,240,844 and USP3,755,269. Double-ended mercapto polybutadiene or double-ended mercapto isoprene liquid rubber has a high apparent viscosity due to the high content of 1,2 structure in the microstructure

Moreover, pseudo-gel phenomenon is prone to occur during the end-capping process, so it affects the average functionality of the polymer.

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