Thermoreversible konjac glucomannan gel crosslinked by borax

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

Guo

et al. 2009

Self Cite

A series of thermoreversible konjac glucomannan gels crosslinked by organic borate were prepared. Required amount of hydrophilic SiO 2 was added into the konjac glucomannan solutions before the crosslinking reaction. The gel network was formed through the crosslinking reaction between borate ions dissociated from organic borate and the cis-diol hydroxyl groups on the mannose units of polysaccharide chains. The rheological properties of the complex gels were studied by dynamic viscoelastic measurement. The gelation kinetics of the complex gels was studied and the critical gelation points of the gels were exactly determined by the Winter-Chambon criterion. The effects of temperature and composite ratio on the shear storage modulus (G′), the loss modulus (G′′) and the sol-gel transition points were investigated.

Section: Sol-gel Transition Pointsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rheological properties of konjac glucomannan/SiO2/organic-borate gels

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

Guo

et al. 2009

Self Cite

“…The room temperature ionic liquid AMIMCl was synthesized according to previous reference [30]. 1-Methylimidazole (22.1 mL) and allyl chloride (26.9 mL) at a molar ratio 1:1.25 were added to a flask (100 mL) fitted with a reflux condenser for 7 h at 65°C under stirring.…”

Section: Synthesis Of Amimclmentioning

confidence: 99%

“…On the other hand, many chemical modifications confering on functional groups to the backbone of KGM can be readily carried out through esterification, etherification, and graft copolymerization [27]. The researches on KGM and its derivatives have being focus on film-forming ability [28], water-absorbing ability [29], gel-forming property [30], rheological property [31], biocompatibility and biodegradability [32]. So far, the only experimental finding about the liquid-crystalline behavior of KGM in aqueous solution was reported by Dave et al [33] in 1998.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of cyanoethyl konjac glucomannan and its liquid crystalline behavior in an ionic liquid

Shen

et al. 2011

J Polym Res

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Cyanoethyl konjac glucomannan (CKGM) products with various degree of substitution (DS) were synthesized, and their chemical structure was characterized by infrared spectroscopy and 1 H and 13 C NMR spectroscopy. Direct evidence of the formation of liquid crystalline phase of cyanoethyl KGM (DS02.10) solution in 1-allyl-3-methylimidazolium chloride (AMIMCl), a room temperature ionic liquid, was confirmed by using polarized optical microscopy (POM). The mesophase and anisotropic phase of cyanoethyl KGM solutions and the phase transition boundaries were investigated by steady shear and dynamic sweep measurements. The crystalline state of the cyanoethyl KGM powder and solution were studied by wide X-ray diffraction.

“…Making use of this phenomenon in chromatography or electrophoresis for the separation of polyhydroxy compounds including carbohydrates is well known . At pH ≥ 12, all boric acid is converted to borate and also polyborate ions should no longer occur . Higher stability of cis ‐ compared to trans ‐1,2‐diols is well known.…”

Section: Introductionmentioning

confidence: 99%

Borate‐Mediated Stereo‐ and Topo‐Selective Methylation of 1,4‐β‐Glucomannan

Macro Chemistry & Physics

Mischnick

2018

Konjak glucomannan (KGM) is methylated with NaOH/MeI in water in the presence of borate and as a reference without this additive. With increasing equiv. of borate increasing suppression of 2‐ and 3‐O‐methylation of mannosyl residues (M) is observed, while glucosyl units (G) are mainly affected at O‐6, but to much lower extent. Raising the temperature and/or addition of acetone as a co‐solvent enhance reactivity, but at the cost of M/G regioselectivity. O‐Methyl konjac glucomannans (M‐KGM) with an average degree of substitution (DS) up to 0.8 and a DS ratio for G and M up to 2 are obtained. From liquid chromatrography–electrospray ionization–mass spectrometry (LC‐ESI‐MS) of the oligosaccharides obtained from M‐KGM, it is concluded that borate‐mediated transient protection might also depend on the location of M within KGM. Comparison with random and block models supports random distribution of M and G in KGM. Thermogravimetric analysis shows higher decomposition temperature of M‐KGMs with increasing DS.