Preparation of hydrogels via ultrasonic polymerization

Cass, Peter; Knower, Warren; Pereeia, Eliana; Holmes, Natalie P.; Hughes, Timothy C.

doi:10.1016/j.ultsonch.2009.08.008

Cited by 72 publications

(36 citation statements)

References 40 publications

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“…The polymerization does not require the use of chemical initiators, although water-soluble additives (sorbitol, glucose or glycerol, especially the latter) are essential for success. 52 This can be attributed to various effects, notably an increase in the population of secondary alkyl radicals which are more stable than hydroxyl radicals. Furthermore, glycerol leads to more viscous solutions, thereby reducing the polymer solubility and hence avoiding depolymerization side reactions.…”

Section: Ultrasound Effects On Polymer Formationmentioning

confidence: 99%

Harnessing mechanochemical effects with ultrasound-induced reactions

Cravotto

Cintas

2012

Chem. Sci.

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Chemical reactions may experience numerous and varied effects under the influence of ultrasound. This soft radiation, often viewed as a lab trick, induces and improves both physical and chemical transformations by means of efficient agitation, dissolution, mass and heat transfers, and reagents sonolysis, which all arise from the cavitational collapse. An empirical rationale that distinguishes between true chemical effects and mechanical ones, especially in heterogeneous reactions, was introduced more than two decades ago and has been a useful guidance on reporting sonochemical mechanisms. Recent studies have witnessed a truly remarkable data set that boosts sonochemistry over the wall of applied science. This perspective highlights the importance of the so-called false sonochemistry-closely related to mechanochemistry-in modern synthesis, thus illustrating the advantages of using pressure waves in chemistry. Emphasis is put on green transformations, mild polymerization reactions and the selective cleavage of functionalized polymers, which may have an effective impact in process chemistry and represent a realistic option in industry.

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Section: Ultrasound Effects On Polymer Formationmentioning

confidence: 99%

Harnessing mechanochemical effects with ultrasound-induced reactions

Cravotto

Cintas

2012

Chem. Sci.

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“…The results indicate that the cavitation effects at lower temperature were more effective than the mechanical effects at higher temperature in the viscosity depression of hydrogel solutions. At higher temperature, clearly the vapor pressure will be higher and so the vapor will enter the cavitation bubble, which leads to the cushioning effect [19,22]. The increased viscosity of the solvent at lower temperatures increases rapid transmission of shock waves and favors the defragmentation of polymer chain at low strain rates [22].…”

Section: Effect Of Temperature On the Rate Of Degradationmentioning

confidence: 99%

“…The effects of various parameters like ultrasound pulse and intensity [12,[17][18][19][20], frequency [20,21], temperature [17,[22][23][24], vapor pressure, volume [19,23,24], solvent [17,22], dissolved gases [21], molecular weight [25,26], and polymer concentration [12,19,20] on the ultrasonic degradation of macromolecules have been studied. The ultrasonic degradation of low density polyethylene at different concentrations, volumes, and temperatures has been studied.…”

Section: Introductionmentioning

confidence: 99%

The Study of Ultrasonic Degradation of Superabsorbent Hydrogels

Ebrahimi

Tarhande

Rafiei

2012

Organic Chemistry International

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Viscometry is a valid and practical approach for monitoring the degradation of polymers in solution. In this work, at constant power and pulse, the effects of different operating parameters such as time of irradiation, temperature, solution concentration, volume, solvent, and immersion depth of horn on the rate of degradation have been investigated in aqueous solution using laboratory scale operation. A method of viscometry was used to study the degradation behavior of aqueous dispersions of microgels. The experimental results show that the viscosity of polymer solution decreased with an increase in the ultrasonic irradiation time and approached a limiting value. The present work has enabled us to understand the role of the different operating parameters in deciding the extent of viscosity reduction in aqueous dispersions of microgels and also the controlling effects of them.

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“…The use of PTC and ultrasound techniques in the area of polymerization has been gaining remarkable consideration in industrial and academic arena because it is a potent and versatile technology which offers several advantages. It has been reported that a combination of PTC and ultrasound condition is a valuable technique to enhance the reaction rate in an organic heterogeneous reactions [51][52][53][54][55][56] and also successfully employed in different polymerization techniques to synthesis polymers [57], homopolymers, block copolymers [58], hydrogels [59] and polymer-inorganic composites, etc. [49].…”

Section: Introductionmentioning

confidence: 99%

Ultrasonic condition boosts up the rate of phase transfer catalyzed polymerization of acrylonitrile in two-phase system

Marimuthu

Murugesan

2017

Appl Petrochem Res

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An ultrasound condition associated with phasetransfer catalyst (PTC) has great diverse applications in synthesis of various organic and polymeric materials because of its fast reaction and high yield in short period of time. Phase transfer catalyst (cetyltrimethylammonium bromide as PTC) extracts the reactive radical anion from aqueous phase and transfer to organic phase whilst ultrasound condition enhances the radical formation; consequently, acrylonitrile was polymerized in ethyl acetate/ water two-phase system at 60 ± 1°C under ultrasound (25 kHz/300 W) and silent condition. The rate of polymerization (R p ) was doubled under ultrasound compare to silent condition. The various experimental parameters such as monomer, initiator, catalyst and temperature, solvent polarity on the rate of polymerization was studied in both conditions. The activation energy (E a ) and other thermodynamic parameters were calculated. The E a value of ultrasound condition supports the enhancement of rate of polymerization. On the basis of observed results, a suitable kinetic model, mechanism and effect of ultrasound in the rate of polymerization were discussed. The obtained polymer was analyzed by TG/DTA and FT-IR. The viscosity average molecular weight of the polymer was found to be 6.8526 9 10 4 g mol -1 .

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Preparation of hydrogels via ultrasonic polymerization

Cited by 72 publications

References 40 publications

Harnessing mechanochemical effects with ultrasound-induced reactions

Harnessing mechanochemical effects with ultrasound-induced reactions

The Study of Ultrasonic Degradation of Superabsorbent Hydrogels

Ultrasonic condition boosts up the rate of phase transfer catalyzed polymerization of acrylonitrile in two-phase system

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