TY - JOUR
T1 - γ-irradiation stability of saturated and unsaturated aliphatic polyanhydrides-ricinoleic acid based polymers
AU - Teomim, D.
AU - Mäder, K.
AU - Bentolila, A.
AU - Magora, A.
AU - Domb, A. J.
PY - 2001
Y1 - 2001
N2 - The effect of terminal sterilization by γ-irradiation on several ricinoleic acid based polyanhydrides was investigated. The following polymers were used: poly(ricinoleic acid maleate) [P(RAM)], poly(ricinoleic acid succinate) [P(RAS)], poly(hydroxy stearic acid succinate) [P(HSAS)], poly(hydroxy stearic acid maleate) [P(HSAM)], and their copolymers with sebacic acid. The polymers were irradiated with an absorbed dose of 2.5 or 10 Mrad by means of a 60Co source under dry ice or at room temperature. No differences were found between samples irradiated under dry ice and at room temperature. Polymers prepared from monomers containing maleate residues, which contain double bonds adjusted to the anhydride linkage along the polymer chain, decreased in molecular weight, became insoluble, and showed fast hydrolytic degradation. For example, p(RAM), p(HSAM), and their copolymers with sebacic acid decreased in Mw from about 10 000 to about 2000, and from about 30 000 to about 5000, respectively, while polymers based on RAS and HSAS remained stable. This phenomenon was explained by an anhydride interchange-self-depolymerization process of the unsaturated anhydride bonds induced by γ-irradiation. This explanation was supported by the depolymerization of another class of polymers having an anhydride bond between two double bonds, fumaric acid anhydride polymers. The anhydride bond that lies between two double bonds was found to be more sensitive to γ-irradiation. This anhydride bond may be cleaved to form two radicals that further react with aliphatic anhydride bonds along the polymer chain to form inter- and/or intracyclization products.
AB - The effect of terminal sterilization by γ-irradiation on several ricinoleic acid based polyanhydrides was investigated. The following polymers were used: poly(ricinoleic acid maleate) [P(RAM)], poly(ricinoleic acid succinate) [P(RAS)], poly(hydroxy stearic acid succinate) [P(HSAS)], poly(hydroxy stearic acid maleate) [P(HSAM)], and their copolymers with sebacic acid. The polymers were irradiated with an absorbed dose of 2.5 or 10 Mrad by means of a 60Co source under dry ice or at room temperature. No differences were found between samples irradiated under dry ice and at room temperature. Polymers prepared from monomers containing maleate residues, which contain double bonds adjusted to the anhydride linkage along the polymer chain, decreased in molecular weight, became insoluble, and showed fast hydrolytic degradation. For example, p(RAM), p(HSAM), and their copolymers with sebacic acid decreased in Mw from about 10 000 to about 2000, and from about 30 000 to about 5000, respectively, while polymers based on RAS and HSAS remained stable. This phenomenon was explained by an anhydride interchange-self-depolymerization process of the unsaturated anhydride bonds induced by γ-irradiation. This explanation was supported by the depolymerization of another class of polymers having an anhydride bond between two double bonds, fumaric acid anhydride polymers. The anhydride bond that lies between two double bonds was found to be more sensitive to γ-irradiation. This anhydride bond may be cleaved to form two radicals that further react with aliphatic anhydride bonds along the polymer chain to form inter- and/or intracyclization products.
UR - http://www.scopus.com/inward/record.url?scp=0034821817&partnerID=8YFLogxK
U2 - 10.1021/bm010078n
DO - 10.1021/bm010078n
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C2 - 11710004
AN - SCOPUS:0034821817
SN - 1525-7797
VL - 2
SP - 1015
EP - 1022
JO - Biomacromolecules
JF - Biomacromolecules
IS - 3
ER -