A gelation mechanism depending on hydrogen bond formation in regioselectively substituted O-methylcelluloses

Sekiguchi, Yuka; Sawatari, Chie; Kondo, Tetsuo

doi:10.1016/s0144-8617(03)00050-x

Cited by 90 publications

(36 citation statements)

References 25 publications

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“…4, the intensity of each peak changed obviously, demonstrating structure transformation induced by ultrasonic treatment and chemical action took place during the preparation of MCC and SNCC. The spectra are normalized at 1,160 cm -1 which assigned to -C-O-stretching vibration within the anhydroglucose ring (Sekiguchi et al 2003). It can be observed that the -C-O-stretching vibration is almost identical, demonstrating that the degradation of cellulose can hardly occur at glucose rings.…”

Section: Ftir Measurementsmentioning

confidence: 99%

Comparing microcrystalline with spherical nanocrystalline cellulose from waste cotton fabrics

et al. 2012

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Microcrystalline cellulose (MCC) and spherical nanocrystalline cellulose (SNCC) were successfully prepared from waste cotton fabrics through acid hydrolysis. The comparative analysis of the morphology and structure between the obtained MCC and SNCC was carried out. The SNCC suspension exhibited higher stability than the MCC suspension. Transmission electron microscopy in combination with atomic force microscopy showed that the cellulose nanospheres with average size of 35 nm were achieved, while the average particle size of MCC was 49 lm. The MCC and SNCC had similar functional groups and crystalline structure as confirmed by Fourier transform infrared spectroscopy and X-ray diffraction analysis, respectively. Viscometric average molecular weight measurement and thermo gravimetric analysis indicated that the degree of polymerization and thermal stability of SNCC was lower than that of MCC. These results should improve understanding of the characteristics of MCC and SNCC derived from waste cotton fabrics and lead to many new applications.

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Section: Ftir Measurementsmentioning

confidence: 99%

Comparing microcrystalline with spherical nanocrystalline cellulose from waste cotton fabrics

et al. 2012

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“…However, at higher temperatures the influence of the hydrophobic group is predominant [18]. Some authors also suggest that not only hydrophobic interaction but also hydrogen bonding may be involved in the gelation mechanism of cellulose derivatives [19].…”

Section: Introductionmentioning

confidence: 99%

Aggregation and gelation in hydroxypropylmethyl cellulose aqueous solutions

Silva

Pinto

Antunes

et al. 2008

Journal of Colloid and Interface Science

115

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In this work we present an analysis of the thermal behavior of hydroxypropylmethyl cellulose aqueous solutions, from room temperature to higher temperatures, above gelation. We focus on significant aspects, essentially overlooked in previous work, such as the correlation between polymer hydrophobicity and rheological behavior, and the shear effect on thermal gelation. Micropolarity and aggregation of the polymer chains were monitored by both UV/vis and fluorescence spectroscopic techniques, along with polarized light microscopy. Gel formation upon heating was investigated using rheological experiments, with both large strain (rotational) tests at different shear rates and small strain (oscillatory) tests. The present observations allow us to compose a picture of the evolution of the system upon heating: firstly, polymer reptation increases due to thermal motion, which leads to a weaker network. Secondly, above 55 • C, the polymer chains become more hydrophobic and polymer clusters start to form. Finally, the number of physical crosslinks between polymer clusters and the respective lifetimes increase and a three-dimensional network is formed. This network is drastically affected if higher shear rates, at nonNewtonian regimes, are applied to the system.

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“…Although the gelation of MC has been extensively studied by various analytical techniques (NMR, differential scanning calorimetry, IR attenuated total reflectance spectroscopy, small-angle neutron scattering, static and dynamic light scattering, and rheology) and the researchers have proposed different gelation mechanisms, the specific molecular interactions that govern this process is still unclear. However, the results of various studies, which were in good agreement one with another, indicated several factors and/or phenomena which play an important role in the gelation of MC [24,[51][52][53][54][55][56][57][58][59][60][61][62][63][64]:…”

Section: Colloidal Dissolution and Gelation As Processes Involved In mentioning

confidence: 53%

Cellulose-Derivatives-Based Hydrogels as Vehicles for Dermal and Transdermal Drug Delivery

Vlaia¹,

Coneac²,

Olariu³

et al. 2016

Emerging Concepts in Analysis and Applications of Hydrogels

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The use of water-soluble polymers of natural, semisynthetic, and synthetic origin for dermal and transdermal drug delivery systems is manifold. Among the most used biopolymers in the formulation of skin preparations, the cellulose ether derivatives as representatives of semisynthetic polymers distinguish through their specific physicochemical properties, by which the pharmacist can select the appropriate cellulose derivative for a particular purpose. The hydrogels containing cellulose derivatives as gelling agents are widely used as water-soluble ointment bases, because they usually associate the characteristics of both conventional and innovative hydrogels, including especially safety, biocompatibility, biodegradability, and a relatively easy way of preparation and low price. The present chapter describes the following issues: the physicochemical properties of water-soluble cellulose derivatives in relationship with their type and grade; physical and chemical properties of cellulose-derivatives-based hydrogels and their compatibility with other auxiliary substances commonly used in the formulation of pharmaceutical hydrogels; the development and manufacturing of these hydrogels on both small and large scales; the characterization of cellulose derivatives hydrogels as pharmaceutical dosage forms through different compendial and noncompendial methods; and well-recognized and novel applications of cellulosederivatives-based hydrogels for dermal and transdermal drug delivery.

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A gelation mechanism depending on hydrogen bond formation in regioselectively substituted O-methylcelluloses

Cited by 90 publications

References 25 publications

Comparing microcrystalline with spherical nanocrystalline cellulose from waste cotton fabrics

Comparing microcrystalline with spherical nanocrystalline cellulose from waste cotton fabrics

Aggregation and gelation in hydroxypropylmethyl cellulose aqueous solutions

Cellulose-Derivatives-Based Hydrogels as Vehicles for Dermal and Transdermal Drug Delivery

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