TY - JOUR
T1 - In-depth characterization of granular starch-graft-polyester compositions as obtained by in situ polymerization of lactones from the starch surface
AU - Rutot-Houzé, Delphine
AU - Degée, Philippe
AU - Gouttebaron, Rachel
AU - Hecq, Michel
AU - Narayan, Ramani
AU - Dubois, Philippe
PY - 2004/6/1
Y1 - 2004/6/1
N2 - The synthesis of poly(ε-caprolactone) (PCL)-grafted granular starch was carried out either in bulk (without solvent) or in toluene suspension by a two-step procedure. First step relied upon the activation of the hydroxyl groups available at the starch surface by alkylaluminum derivatives like AlEt3 and removal of non-surface-grafted organo-aluminum active species. The latter species were made free in solution by reaction with the remaining water molecules still contaminating the polymerization medium despite intensive drying of the starch granules. In the second step, ε-caprolactone was polymerized via a coordination-insertion ring-opening polymerization as initiated by the surface-grafted aluminum alkoxide species. The present contribution aims at investigating various parameters such as nature of the alkyl aluminum activator and monomer (δ-valerolactone was studied as well), temperature, concentration, and addition of a solvent (polymerization in toluene suspension), reaction time, and also the experimental procedure used to recover the polyester chains and measure the grafting efficiency. It turns out that, under the studied conditions, dialkylaluminum alkoxides surface-grafted onto the starch granules were more likely generated and promote a fast polymerization reaction with the formation of grafted PCL chains with a molecular weight that can be as high as 225 000 (Mn value) for polymerization carried out in toluene suspension.
AB - The synthesis of poly(ε-caprolactone) (PCL)-grafted granular starch was carried out either in bulk (without solvent) or in toluene suspension by a two-step procedure. First step relied upon the activation of the hydroxyl groups available at the starch surface by alkylaluminum derivatives like AlEt3 and removal of non-surface-grafted organo-aluminum active species. The latter species were made free in solution by reaction with the remaining water molecules still contaminating the polymerization medium despite intensive drying of the starch granules. In the second step, ε-caprolactone was polymerized via a coordination-insertion ring-opening polymerization as initiated by the surface-grafted aluminum alkoxide species. The present contribution aims at investigating various parameters such as nature of the alkyl aluminum activator and monomer (δ-valerolactone was studied as well), temperature, concentration, and addition of a solvent (polymerization in toluene suspension), reaction time, and also the experimental procedure used to recover the polyester chains and measure the grafting efficiency. It turns out that, under the studied conditions, dialkylaluminum alkoxides surface-grafted onto the starch granules were more likely generated and promote a fast polymerization reaction with the formation of grafted PCL chains with a molecular weight that can be as high as 225 000 (Mn value) for polymerization carried out in toluene suspension.
KW - Coordination-insertion
KW - Poly(ε-caprolactone)
KW - Ring-opening polymerization
KW - Starch
KW - Surface grafting
UR - http://www.scopus.com/inward/record.url?scp=2542501490&partnerID=8YFLogxK
U2 - 10.1002/pi.1387
DO - 10.1002/pi.1387
M3 - Article
AN - SCOPUS:2542501490
SN - 0959-8103
VL - 53
SP - 656
EP - 663
JO - Polymer international
JF - Polymer international
IS - 6
ER -