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

2011 
This article describes detailed structure-property relationships of 5 regioselectively methylated celluloses and 10 diblock cellulose derivatives with regioselective functionalization patterns: methyl 2,3,6-tri-O- (1, 236MC), methyl 2,3-di-O- (2, 23MC), methyl 2,6-di-O- (3, 26MC), methyl 3-O- (4, 3MC), methyl 6-O-methyl-cellulosides (5, 6MC), methyl β-D-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl- (6, G-236MC), methyl β-D-glucopyranosyl-(1→4)-2,3-di-O-methyl- (7, G-23MC), methyl β-D-glucopyranosyl-(1→4)-2,6-di-O-methyl- (8, G-26MC), methyl β-D-glucopyranosyl-(1→4)-3-O-methyl- (9, G-3MC), methyl β-D-glucopyranosyl-(1→4)-6-O-methyl- (10, G-6MC), methyl β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl- (11, GG-236MC), methyl β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→4)-2,3-di-O-methyl- (12, GG-23MC), methyl β-D-glucopy-ranosyl-(1→4)-β-D-glucopyranosyl-(1→4)-2,6-di-O-methyl- (13, GG-26MC), methyl β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→4)-3-O-methyl- (14, GG-3MC), and methyl β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→4)-6-O-methyl-cellulosides (15, GG-6MC). Surface tension, differential scanning calorimetry, fluorescence, and dynamic light scattering measurements of aqueous solutions of compounds 1–15 revealed that there was no relationship between aggregation behaviors and gel formation, gelation occurred only when the hydrophobic environments formed by hydrophobic interactions between the sequences of 2,3,6-tri-O-methyl-glucopyranosyl units upon heating. The diblock structure consisting of cellobiosyl block and approx. ten 2,3,6-tri-O-methyl-glucopyranosyl units was of crucial importance for thermoreversible gelation of methylcellulose. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1539–1546, 2011
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