The aim was the synthesis of chain-extended poly(ethylene glycol) (PEG) derivatives containing periodic side-chain carboxyl groups. The chain extension of PEG diols with pyromellitic dianhydride was performed in toluene or dimethylformamide solution and in bulk. The degree of chain extension (DoCE) was between 6 and 21, the highest value being recorded when the reaction was performed using low-molecular-weight PEG. The recorded limited increase of molecular weight could be at least partially attributed to the rather low reactivity of the aromatic dianhydride. To overcome this issue, a more reactive aliphatic dianhydride, ethylenediaminetetraacetic dianhydride (EA), was tested. However, the reaction of PEG with EA only afforded a DoCE of 2.5. Appreciably higher DoCE values were obtained when EA was reacted with bisamino-terminated PEG. Independent of prepolymer and dianhydride structure, all chain-extended products displayed less of a tendency to crystallization than the starting prepolymer, very likely due to interference by anhydride residues. The low in vitro cytotoxicity of the chain-extended polymers and the presence of carboxyl groups point to their possible use in biomedical applications, particularly in controlled drug release and tissue engineering.
Poly(ethylene glycol) derivatives containing periodic side-chain carboxyl groups: synthesis and characterization
ALTOMARE, ANGELINA;CHIELLINI, FEDERICA;SOLARO, ROBERTO
2015-01-01
Abstract
The aim was the synthesis of chain-extended poly(ethylene glycol) (PEG) derivatives containing periodic side-chain carboxyl groups. The chain extension of PEG diols with pyromellitic dianhydride was performed in toluene or dimethylformamide solution and in bulk. The degree of chain extension (DoCE) was between 6 and 21, the highest value being recorded when the reaction was performed using low-molecular-weight PEG. The recorded limited increase of molecular weight could be at least partially attributed to the rather low reactivity of the aromatic dianhydride. To overcome this issue, a more reactive aliphatic dianhydride, ethylenediaminetetraacetic dianhydride (EA), was tested. However, the reaction of PEG with EA only afforded a DoCE of 2.5. Appreciably higher DoCE values were obtained when EA was reacted with bisamino-terminated PEG. Independent of prepolymer and dianhydride structure, all chain-extended products displayed less of a tendency to crystallization than the starting prepolymer, very likely due to interference by anhydride residues. The low in vitro cytotoxicity of the chain-extended polymers and the presence of carboxyl groups point to their possible use in biomedical applications, particularly in controlled drug release and tissue engineering.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.