Making poly(alkylene carbonates) of controlled molecular weight

Details Making poly(alkylene carbonates) of controlled molecular weight Making poly(alkylene carbonates) of controlled molecular weight

1989-06-08

1990-07-24

Nielsen, Earl

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From heterocyclic reactant containing as ring atoms oxygen,...

C08G 6402, C08G 6434

Patent

active

049436775

ABSTRACT:
Poly(alkylene carbonates) of controlled molecular weight are made by copolymerizing carbon dioxide and one or more oxirane compounds using zinc polycarboxylate catalyst in the presence of a sterically hindered organic proton donor. The acidity of the donor is in the range of 3 to 20 pK.sub.a and the steric quality of the donor is such that it has a steric parameter (E.sub.s) of -0.38 or less. The molecular weight of the polymer can be regulated by altering the level of proton donor over a range which does not adversely affect catalyst productivity. Benzoic acid and phenol are examples of suitable proton donors. The preferred catalyst is one made from zinc oxide and a dicarboxylic acid, such as glutaric acid or adipic acid.

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