Synthesis and thermoreversible gelation of diblock methylcellulose analogues via Huisgen 1,3-dipolar cycloaddition
- 495 Downloads
A novel synthetic method to link acetylated cellulose derivatives with methylated cellulose derivatives via Huisgen 1,3-dipolar cycloaddition was developed to produce 1,2,3-triazole-linked diblock copolymers consisting of hydrophilic cellobiose or low-molecular-weight cellulose and a hydrophobic 2,3,6-tri-O-methyl-cellulose. Huisgen 1,3-dipolar cycloaddition had the advantage over glycosylation reaction of being able to connect a hydrophilic block having higher molecular weight than cellobiose with a hydrophobic 2,3,6-tri-O-methyl-cellulose block. As a consequence, 2.0 wt% aqueous solutions of the 1,2,3-triazole-linked diblock methylcellulose analogues exhibited the thermoreversible gelation in water at around 25 °C as same as that of β-(1 → 4)-linked diblock methylcellulose. Differential scanning calorimetry measurements of 2.0 wt% aqueous solutions of the diblock copolymers revealed that an important structural factor for its thermoreversible gelation was not a β-(1 → 4)-glycosidic linkage between hydrophilic and hydrophobic blocks of diblock methylcellulose, but a sequence of anhydro 2,3,6-tri-O-methyl-glucopyranosyl units and that of unmodified glucopyranosyl ones.
KeywordsDiblock copolymer Methylcellulose Click chemistry Triazole Thermoreversible gelation DSC
This investigation was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science, and Culture of Japan (Nos. 18680009 and 21580205).
- Bodvik R, Dedinaite A, Karlson L, Bergström M, Bäverbäck P, Pedersen JS, Edwards K, Karlsson G, Varga I, Claesson PM (2010) Aggregation and network formation of aqueous methylcellulose and hydroxypropylmethylcellulose solutions. Colloids Surf A Physicochem Eng Aspects 354(1–3):162–171CrossRefGoogle Scholar
- Nakagawa A, Fenn D, Koschella A, Heinze T, Kamitakahara H (2011a) Physical properties of diblock methylcellulose derivatives with regioselective functionalization patterns: first direct evidence that a sequence of 2,3,6-tri-O-methyl-glucopyranosyl units causes thermoreversible gelation of methylcellulose. J Polym Sci, Part B: Polym Phys 49(21):1539–1546CrossRefGoogle Scholar