A method for preparing a polymeric reagent is provided, which method includes the optional step of forming an N-hydroxysuccinimdyl ester derivative. Related methods, preparations, and so forth are also provided.

A biodegradable crosslinked polymer which is a reaction product of a polymer having aldehyde-reactive functional groups and a polyaldehyde, wherein the polymer having aldehyde-reactive functional groups comprises a biodegradable structure or the polyaldehyde comprises a biodegradable structure.

The present invention relates to a process for preparing polyether polyols by addition of alkylene oxides onto H-functional starter substances, characterized in that at least one urethane alcohol of formula (II) where R.sup.1 is linear or branched C.sub.2 to C.sub.24-alkylene which may optionally be interrupted by heteroatoms such as O, S or N and may be substituted, R.sup.2 is linear or branched C.sub.2 to C.sub.24-alkylene which may optionally be interrupted by heteroatoms such as O, S or N and may be substituted, R is H, linear or branched C.sub.1 to C.sub.24-alkyl, C.sub.3 to C.sub.24-cycloalkyl, C.sub.4 to C.sub.24-aryl, C.sub.5 to C.sub.24-aralkyl, C.sub.2 to C.sub.24-alkenyl, C.sub.2 to C.sub.24-alkynyl, each of which may optionally be interrupted by heteroatoms such as O, S or N and/or each of which may be substituted by alkyl, aryl and/or hydroxyl, is used as H-functional starter compound. The invention further provides the polyether polyols containing a urethane group, the polyether polyols obtainable by the process according to the invention, for the use of the inventive polyether polyols for preparation of a polyurethane polymer, and the resulting polyurethane polymers.

Among other aspects, provided herein are multi-armed polymer conjugates comprising an alkanoate-linker, compositions comprising such conjugates, and related methods of making and administering the same. Methods of treatment employing such conjugates and related uses are also provided. The conjugates are prepared with high drug loading efficiencies.

A method for producing an activated polyethylene glycol compound having a carbamate bond between a polyethylene glycol moiety and a functional group capable of reacting with a bio-related substance or a precursor of the functional group, includes: reacting a polyethylene glycol raw material having a nitrophenyl group at a terminal thereof with an amine compound having the functional group capable of reacting with the bio-related substance or the precursor of the functional group in a solution containing an aprotic solvent to obtain a reaction mixture containing the activated polyethylene glycol compound and 4-nitrophenol; adding a basic aqueous solution having a pH of 10 or more and 14 or less to the reaction mixture to obtain a two-phase mixture; and separating an organic layer of the two-phase mixture from an aqueous layer of the two-phase mixture and recovering the activated polyethylene glycol compound from the organic layer.

A biodegradable crosslinked polymer which is a reaction product of a polymer having aldehyde-reactive functional groups and a polyaldehyde, wherein the polymer having aldehyde-reactive functional groups comprises a biodegradable structure or the polyaldehyde comprises a biodegradable structure.