A rapid, non-invasive and non-destructive method for studying swelling behavior and microstructure variations of hydrogels

Li, Yaqiong; Li, Xiunan; Chen, Chao; De, Zhao; Su, Zhiguo; Ma, Guanghui; Yu, Rong

doi:10.1016/j.carbpol.2016.06.054

Cited by 62 publications

(25 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Concerning the structure investigation, the effort has been addressed mainly toward the understanding of the liquid crystalline self-assembly resulting in ordered helical structures with peculiar mechanical and optical properties [7][8][9]. The self-assembly of NC or NC-composites into soft hydrogels [10,11] has been characterized in terms of macroscopic parameters such as mesh size, charge density, gelation rate, mechanical performances, or stability [12][13][14][15]. In this context, rheology experiments have been performed and a gel-like behavior of NC suspensions with an elastic response even at a low concentration [16] has been reported.…”

Section: Introductionmentioning

confidence: 99%

Role of sonication pre-treatment and cation valence in the sol-gel transition of nano-cellulose suspensions

Maestri

Abrami

Hazan

et al. 2017

Sci Rep

View full text Add to dashboard Cite

Sol-gel transition of carboxylated cellulose nanocrystals has been investigated using rheology, SAXS, NMR and optical spectroscopies to unveil the distinctive roles of ultrasound treatments and addition of various cations. Besides cellulose fiber fragmentation, sonication treatment induces fast gelling of the solution. The gelation is independent of the addition of cations, while the final rheological properties are highly influenced by the type, concentration and sequence of the operations since the cations must be added prior to sonication to produce stiff gels. The gel elastic modulus was found to increase proportionally to the ionic charge rather than the cationic size. In cases where ions were added after sonication, SAXS analysis of the Na+ hydrogel and Ca2+ hydrogel indicated the presence of structurally ordered domains in which water is confined, and 1H-NMR investigation showed the dynamics of water exchange within the hydrogels. Conversely, separated phases containing essentially free water were characteristic of the hydrogels obtained by sonication after Ca2+ addition, confirming that this ion induces irreversible fiber aggregation. The rheological properties of the hydrogels depend on the duration of the ultrasound treatments, enabling the design of programmed materials with tailored energy dissipation response.

show abstract

Section: Introductionmentioning

confidence: 99%

Role of sonication pre-treatment and cation valence in the sol-gel transition of nano-cellulose suspensions

Maestri

Abrami

Hazan

et al. 2017

Sci Rep

View full text Add to dashboard Cite

show abstract

“…Although both T 1 and T 2 (and consequently R 1 and R 2 ) of a sample can be extracted simultaneously from a CP‐CWFP experiment, T 2 is prone to interference arising from features not linked to the free‐radical effect on relaxation, such as chemical exchange and diffusion . The influence of these factors is better observed when relaxation time distributions are plotted for each monitored period of the reaction.…”

Section: Resultsmentioning

confidence: 99%

“…water molecules with restricted molecular mobility due to interactions with the solute. Their presence during the reactions is observed as isolated spots on the map's surface at T 2 values smaller than 3 s, which is the transverse relaxation time of bulk, non‐solvating water molecules in the spectrometer's magnetic field strength (0.54 T) . The number and intensity of relaxation domains pertaining to water molecules with restricted mobility is positively correlated with the monomer feed during the sample formulation, being in all likelihood the consequence of the solvation process undergone by the newly created polymer chains.…”

Section: Resultsmentioning

confidence: 99%

Real‐time monitoring by proton relaxometry of radical polymerization reactions of acrylamide in aqueous solution

Rodrigues¹,

Neto²,

Sebastião

et al. 2018

Polymer International

View full text Add to dashboard Cite

The potential of time‐domain nuclear magnetic resonance (TD‐NMR) for the real‐time monitoring of solution radical polymerizations is demonstrated. A model system composed of a redox‐pair initiator system, acrylamide as monomer and water as solvent was investigated. A second‐generation continuous wave free precession technique was employed to measure the longitudinal relaxation time constant (T1) of the samples throughout the polymerization reactions. This parameter was shown to be sensitive to the reactant feed free‐radical enhancement of the water molecule relaxation time, making it a good probe to monitor monomer conversion in real time in an automated, non‐destructive fashion. It was found that the T1 value was better than the transverse relaxation time constant (T2) for describing the evolution of the polymerization reactions, due to its greater sensitivity to paramagnetic effects. The TD‐NMR signal variation observed was linked to the formation, propagation and termination steps of the radical polymerization kinetics scheme. These first results may contribute to the application of real‐time monitoring of radical polymerization reactions employing low‐cost and robust TD‐NMR spectrometers. © 2018 Society of Chemical Industry

show abstract

“…In the copolymer–water mixtures, two types of major peaks due to water are observed in Figure (B–E), in the region from 20 to 100 ms and in the region from 200 to 500 ms. Their shift from the single water peak in Figure (A) reflects chemical exchanges with labile protons on the polymers as well as diffusive exchange of water in different microenvironment. The shorter the T 2 relaxation time, the harder to exchange and the slower the re‐orientational mobility of the water molecules . Peaks d, h, l, and p can all be assigned to the tightly bound water molecules with very restricted rotational mobility (slow re‐orientational mobility) in the copolymers, while peaks e, i, m, and t can all be attributed to the loosely bound water with fast re‐orientational mobility in the polymers (the minor peaks below 10 ms are due to the protons in the polymer).…”

Section: Resultsmentioning

confidence: 99%

“…This important parameter reveals different mobility and distributions of water components in the aqueous system. Because of the chemical exchange between water protons and labile protons on a polymer as well as the diffusive exchange of water in different microenvironment, T 2 of water protons in polymer solution is usually smaller than that in neat water . Therefore, T 2 of water protons also gives indirect information on the polymer chain dynamics.…”

Section: Introductionmentioning

confidence: 99%

Studies of relationship between polymer structure and hydration environment in amphiphilic polytartaramides

Chi

Cao

et al. 2016

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

The relationships between the chemical structures and hydration environment of the polymers can provide significant insight into the water‐amphiphilic polymer interactions. Here, the hydrophobicity of amphiphilic block copolymers poly(ethylene tartaramide‐b‐alkyl isocyanate) is gradually tuned by using of a series of pendant alkyl (isopropyl, n‐butyl, cyclopentyl, and cyclohexyl) groups. Dynamics of hydration probed by low‐field NMR relaxometry exhibits a heterogeneous environment of water molecules, corresponding to tightly bound water with slow re‐orientational mobility and loosely bound water with fast re‐orientational mobility. Progressively larger amounts of bound water are present in the copolymers, ongoing from pendant isopropyl, n‐butyl, cyclopentyl, and finally to cyclohexyl group. Water in the copolymer bearing the cyclohexyl group has a significantly high partial specific heat capacity. Therefore, hydrophobic interaction between the polymer and water is enhanced when the hydrophobicity of the polymer is increased, resulting in considerable hydrophobic hydration with decreased mobility of the bound water. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 138–145

show abstract

A rapid, non-invasive and non-destructive method for studying swelling behavior and microstructure variations of hydrogels

Cited by 62 publications

References 40 publications

Role of sonication pre-treatment and cation valence in the sol-gel transition of nano-cellulose suspensions

Role of sonication pre-treatment and cation valence in the sol-gel transition of nano-cellulose suspensions

Real‐time monitoring by proton relaxometry of radical polymerization reactions of acrylamide in aqueous solution

Studies of relationship between polymer structure and hydration environment in amphiphilic polytartaramides

Contact Info

Product

Resources

About