Carboxylation method of polyoxyethylene-poly-oxypropylene polyoxyethylene copolymer

Abstract

The invention discloses a method for the carboxylation of a polyoxyethylene-polyoxypropylene-polyoxyethylene copolymer. The method comprises the following steps: allowing the addition reaction of an unsaturated nitrile compound and PEO-PPO-PEO block polymer in an aqueous solution in the presence of alkaline catalysts, hydrolyzing nitrile groups contained in the addition reaction product under alkaline or acidic conditions, extracting the crude product of carboxyl PEO-PPO-PEO block polymer from the hydrolysate by using organic solvents, and purifying by ether precipitation method to obtain a purified carboxyl PEO-PPO-PEO block polymer. The method has mild conditions and avoids the cleavage of ether bonds in PEO-PPO-PEO block polymer. Corresponding chemical bonds can be introduced to the original polymer structure during the carboxylation process as required so as to produce a modified product with uniform structure and stable performance. Furthermore, the method is suitable for mass preparation and industrial production.

Description

technical field [0001] The invention relates to a synthesis method in the technical field of polymer materials, in particular to a method for carboxylation of polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymers. Background technique [0002] Polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO-PPO-PEO) block copolymer is a polymer compound in which the hydrophilic PEO segment and the hydrophobic PPO segment are linked together by covalent bonds. A class of nonionic polymer surfactants, trade name Pluronic (BASF Company) or Poloxamer (ICI Company), as polymer nonionic surfactants, can be used as defoamers, emulsifiers, demulsifiers, lubricants Compared with low molecular surfactants, PEO-PPO-PEO copolymers have more superior properties, such as extremely low critical micelle concentration, The diversification of molecular chemical composition and the resulting diversification of amphiphilic properties, extremely low toxicity, good biocompatibility and protein ...

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Problems solved by technology

[0003] However, the terminal hydroxyl activity of the PEO-PPO-PEO copolymer itself is very small, which limits its further application in many fields. It is necessary, and one of the important methods is to carboxylate PEO-PPO-PEO. Common hydroxyl carboxylation methods can be divided into two categories: the first category is to introduce carboxyl groups on hydroxyl groups through chemical reactions. The more common method is through The disadvantage of the reaction between hydroxyl and acid anhydride is that the reaction product contains ester bonds, and the ester bonds are easily decomposed in the human body, which will reduce the half-life of the drug-carrying system in the human body, and this method requires an anhydrous environment. PEG It is also very easy to absorb water, so it is extremely inconvenient and expensive; the second type is to directly convert hydroxyl groups into carboxyl groups, often using potassium permanganate to oxidize hydroxyl groups to obtain carboxylated products. fracture

[0004] Found through document retrieval to prior art, Iwasaki Keiji etc. published patent " Hemoglobin combined with a poly(alkylene oxide) " (hemoglobin Links with polyoxyalkylene), the patent proposes to use milder manganese dioxide to oxidize hydroxyl groups to aldehyde groups, and then use hydrogen peroxide to oxidize aldehyde groups to carboxyl groups. The disadvantage is that the yield of this method is very low, only 30%

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