Preparation process of polyester carbonate with high molecular weight whole alternant structure

Abstract

The invention is a method of preparing high-molecular weight fully alternative structural polycarbonate, providing a method of preparing high-molecular weight, highly alternative structural plycarbonate by using two-component catalyst to selectively catalyze epoxy alkane and carbon dioxide to react at low pressure or medium pressure. The two-component catalyst is composed of a primary catalyst tetradentate Schiff alkali metal complex (R1)(R2)SalenMX and an aid-catalyst R1R23YX1 salt, where R1 and R2 in (R1)(R2)SalenMX are -H, C1-C6 alkyls, C1-C6 alkoxys, -Cl,-Br or -NO2; M is trivalent metallic cation; X is monovalent anion; R1 and R2 in the salt are alkyls, Y is family-five element and X1 is monovalent anion. The molar ration of the primary catalyst to the aid-catalyst is 0.2-5 : 1. The catalytic efficiency reaches 10 to the power 5 g polymer / mol catalyst, the molecular weight of the polymer is over 30000, the molecular weight distribution is less than 2, the alternative structure is over 99%. The method has moderate reacting conditions, and simple operation; the used catalyst is simple to synthesize, low-cost, high-activity, and suitable for industrialized application.

Description

technical field [0001] The invention belongs to the technical field of polymer materials. The invention relates to a method for preparing high-molecular-weight polycarbonate with complete alternating structure, which is efficient, simple and has relatively mild reaction conditions. Background technique [0002] Carbon dioxide is the main gas that causes the greenhouse effect, and it is also one of the most abundant carbon sources on earth. The chemical fixation of carbon dioxide is an important research field of green chemistry. Among them, a main direction of utilizing carbon dioxide is to prepare polycarbonate by copolymerizing it with alkylene oxide under the action of a catalyst. The high polymer can be photodegraded and biodegraded; meanwhile, it has excellent performance of blocking oxygen and water. Therefore, polycarbonate can be used as engineering plastics, biodegradable non-polluting materials, disposable medical and food packaging materials, adhesives, and com...

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Problems solved by technology

Japanese published patents JP 02142824 and JP 02575199 use expensive porphyrin complexes to catalyze carbon dioxide and alkylene oxides to synthesize polycarbonate, with a catalytic efficiency of 10 3 ~10 4 gram of polymer / mole of catalyst, but the molecular weight of the polymer is only about 5000, and the reaction time needs more than 10 days

Chinese patent application numbers CN 89100701.6 and CN 91109459.8 disclose a bimetallic catalyst system supported by polymers with anion coordination, and can also obtain 10 4 Catalytic efficiency in grams of polymer per mole of catalyst, but the support is difficult to separate from the resulting polycarbonate

In U.S. Patent US 6133402 and J.Am.Chem.Soc., (2002, 124, 14284), Coates described a highly active single-site organozinc catalyst with catalytic activity for the reaction of carbon dioxide and propylene oxide As high as 235 moles of product / mole of catalyst per hour, polypropylene carbonate with a molecular weight of 20,000 to 40,000 and a narrow distribution is obtained, but simultaneously 13 to 25% of cyclic propylene carbonate by-products are also produced

[0004] Most of the above methods for preparing polycarbonate have low catalyst activity, long reaction time, and high pressure, requiring organic solvents; accompanied by the production of cyclic carbonate by-products or low carbonate units in the polymerization product; difficulty in separating the product from the catalyst, etc. question

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