To provide a highly heat resistant flame retardant. A polymer having repeating units represented by the following formula (1), which has a weight average molecular weight as calculated as standard polystyrene of at least 6,000: ##STR00001##
wherein R is a C.sub.1-6 alkylene group, —S— or —SO.sub.2—.

To provide a highly heat resistant flame retardant.

A polymer having repeating units represented by the following formula (1), which has a weight average molecular weight as calculated as standard polystyrene of at least 6,000:

##STR00001##

wherein R is a C.sub.1-6 alkylene group, S or SO.sub.2.

The present invention relates to a polymer including repeating units of the following general formula (1): ##STR00001##
wherein R.sub.1, R.sub.2, m, k and the asterisks are as defined in the specification and the claims, and wherein the bromine content in the polymer being 45 to 80 wt %, as well as to a method for producing such polymers.

A modification of natural or synthetic polysaccharides by grafting polyetheramines, and the use of modified polysaccharides in the form of a hydrogel as a medium for cell culture. These hydrogel preparations may have heat-sensitive rheological properties that are interesting for their intracorporeal use in human and veterinary medicine, for cell culture and transport of biological samples.

The present invention relates to a polymer including repeating units of the following general formula (1):

##STR00001##

wherein R.sub.1, R.sub.2, m, k and the asterisks are as defined in the specification and the claims, and wherein the bromine content in the polymer being 45 to 80 wt %, as well as to a method for producing such polymers.