title: Controlled graft copolymerization of lactic acid onto starch in a supercritical carbon dioxide medium.
abstract: This work presents a new approach for the synthesis of a starch-g-poly L-lactic acid (St-g-PLA) copolymer via the graft copolymerization of LA onto starch using stannous 2-ethyl hexanoate (Sn(Oct)2) as a catalyst in a supercritical carbon dioxide (scCO2) medium. The effects of several process parameters, including the pressure, temperature, scCO2 flow rate and reaction time, on the polymerization yield and grafting degree were studied. Amorphous graft St-g-PLA copolymers with increased thermal stability and processability were produced with a high efficiency. The maximum grafting degree (i.e., 52% PLA) was achieved with the following reaction conditions: 6h, 100°C, 200 bar and a 1:3 (w/w) ratio of St/LA. It was concluded that these low cost biobased graft biopolymers are potential candidates for several environment-friendly applications.
authors.affiliation: Hacettepe University, Chemical Engineering Department and Bioengineering Division, 06800 Çankaya, Ankara, Turkey. Electronic address: salimi@hacettepe.edu.tr.
authors.forename: Kouroush
authors.initials: K
authors.lastname: Salimi
authors.affiliation: Hacettepe University, Chemical Engineering Department and Bioengineering Division, 06800 Çankaya, Ankara, Turkey. Electronic address: ylmzmehmet@yahoo.com.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Yilmaz
authors.affiliation: Hacettepe University, Chemical Engineering Department and Bioengineering Division, 06800 Çankaya, Ankara, Turkey. Electronic address: rzayevzmo@gmail.com.
authors.forename: Zakir M O
authors.initials: ZMO
authors.lastname: Rzayev
authors.affiliation: Hacettepe University, Chemical Engineering Department and Bioengineering Division, 06800 Çankaya, Ankara, Turkey; Biyomedtek/NanoBiyomedtek, 06800 Çankaya, Ankara, Turkey. Electronic address: piskin@hacettepe.edu.tr.
authors.forename: Erhan
authors.initials: E
authors.lastname: Piskin
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry* / Q000378:metabolism; D019344:Lactic Acid / Q000737:chemistry* / Q000378:metabolism; D011091:Polyesters; D058105:Polymerization; D011108:Polymers / Q000737:chemistry* / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013213:Starch / Q000737:chemistry* / Q000378:metabolism; D014961:X-Ray Diffraction
chemical_list: D011091:Polyesters; D011108:Polymers; D002245:Carbon Dioxide; D019344:Lactic Acid; C033616:poly(lactide); D013213:Starch
keywords: Graft copolymerization; Lactic acid; Starch; Supercritical carbon dioxide