Enhanced film-forming properties for ethyl cellulose and starch acetate using n-alkenyl succinic anhydrides as novel plasticizers.
OBJECTIVE
The aim of this study was to investigate the ability of n-alkenyl succinic anhydrides (n-ASAs) to improve the film-forming characteristics of a novel coating polymer, potato starch acetate degree of substitution 2.8 (SA). n-ASAs were also applied to improve the otherwise brittle properties of ethyl cellulose (EC) aqueous dispersion (Aquacoat) and EC solvent-based films.


METHODS
The effectiveness of two n-ASAs, 2-octenyl succinic anhydride (OSA) and 2-dodecen-1-ylsuccinic anhydride were evaluated as plasticizers. Mechanical properties, both water vapor and drug permeabilities, and glass transition temperatures of the cast free films were measured. Triethyl citrate and dibutyl sebacate were used as reference plasticizers.


RESULTS
The long hydrocarbon chain of n-ASA, with its accessible carbonyl groups, enabled a strong plasticization effect on the tested polymers. Due to the excellent mechanical properties (i.e., a tough film structure with considerable flexibility) and low permeability of the plasticized films, n-ASAs, and especially OSA proved to be an ideal plasticizer particularly for EC based coatings. Also, the EC aqueous dispersion plasticized with n-ASAs resulted in a markedly enhanced coalescence of the colloidal polymer particles, even at low drying temperatures.


CONCLUSIONS
In applications where a coating with high flexibility is required, n-ASAs can be used as plasticizers at moderately high concentrations (up to 60-70%, w/w) without losing the high tensile strength, excellent toughness and low permeability of EC and SA films.
Tarvainen
Maarit
M
Department of Pharmaceutics, University of Kuopio, P.O. Box 1627, FIN-70211, Kuopio, Finland. maarit.tarvainen@uku.fi
Sutinen
Riitta
R
Peltonen
Soili
S
Mikkonen
Hannu
H
Maunus
Jaana
J
Vähä-Heikkilä
Kalle
K
Lehto
Vesa-Pekka
VP
Paronen
Petteri
P
D000465:Algorithms; D002152:Calorimetry, Differential Scanning; D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002951:Citrates; D003460:Crystallization; D003998:Dicarboxylic Acids; D010539:Permeability; D010968:Plasticizers / Q000737:chemistry*; D012997:Solvents; D013213:Starch / Q000031:analogs & derivatives* / Q000737:chemistry*; D013387:Succinic Anhydrides / Q000737:chemistry*; D013718:Tensile Strength; D014867:Water
D002951:Citrates; D003998:Dicarboxylic Acids; D010968:Plasticizers; D012997:Solvents; D013387:Succinic Anhydrides; D014867:Water; C055481:dibutyl sebacate; C013517:ethyl cellulose; C023001:ethyl citrate; D002482:Cellulose; D013213:Starch; C050766:starch acetate