Synthesis and characterization of biodegradable aliphatic copolyesters with hydrophilic soft segments

Abstract

segmented poly(ester-ether)s based on poly(butylene succinate) and two different types of polyethers were investigated. The poly(ester-ether)s were synthesized by transesterification reaction of dimethyl succinate 1,4-butanediol and poly(ethylene oxide) (PEO, Mn = 1000 g/mol) in the first series, and poly(tetramethylene oxide) (PTMO,Mn = 1000 g/mol) in the second. The mass fraction of soft segments was varied between 10 and 50 mass. %. The effect of the introduction of two different polyether soft segments on the structure, thermal and rheological properties were investigated. The composition of the poly(ester-ether)s, determined from their 1H-NMR spectra showed that incorporation of soft polyether segments was successfully performed by the transesterification reaction in bulk. The molecular weight was estimated from solution viscosity measurements and complex dynamic viscosities. The thermal properties investigated by DSC indicated that the presence of soft segments lowers the melting and crystallization temperature of the hard phase, as well as the degree of crystallinity. Dynamical mechanical analysis was used to investigate the influence of composition on the rheological behavior of the segmented poly(ester-ether)s. The results obtained from an enzymatic degradation test performed on some of the synthesized polymers showed that the biodegradability is enhanced with increasing hydrophilicity.

U okviru ovog rada ispitana je sinteza i fizička svojstva dve serije segmentiranih poli(estar-etara) na bazi poli(butilen-sukcinata) i dva tipa različitih polietara. Poli(estar-etri) su sintetisani reakcijom transesterifikacije polazeći od dimetil-sukcinata, 1,4-butandiola i poli(etilen-oksida) (PEO, Mn = 1000 g/mol) u prvoj seriji, i poli(tetrametilen-oksida) (PTMO, Mn = 1000 g/mol) u drugoj seriji. Maseni udeo mekih segmenata u obe serije je variran od 10 do 50 mas. %. Izučavan je uticaj uvođenja različitih polietarskih mekih segmenata na strukturu, kao i termička i reološka svojstva. Na osnovu sastava poli(estar-etara) određenih iz 1H-NMR spektara je pokazano da je uvođenje mekih polietarskih segmenata uspešno izvedeno reakcijom transesterifikacije u rastopu. Molarna masa je procenjena na osnovu graničnih viskozitetnih brojeva i kompleksnih dinamičkih viskoziteta. Diferencijalnom skenirajućom kalorimetrijom je utvrđeno da se uvođenjem mekih segmenata snižavaju temperature topljenja i kristalizacije tvrde faze. Stepen kristaliničnosti celog uzorka, procenjen na osnovu promena entalpija topljenja, smanjuje se, dok je stepen kristaličnosti tvrde faze isti kao kod homopolimera ili nešto veći pri većim udelima mekih segmenata. Ispitivanje uticaja sastava na reološka svojstva poli(estar-etara) je izvedeno dinamičko-mehaničkom analizom. Rezultati dobijeni u testovima enzimske razgradnje pokazuju da se biodegradabilnost povećava sa povećanjem hidrofilnosti polimera.