Investigation of the influence of freeze-thaw processing on the properties of polyvinyl alcohol/polyacrylic acid complexes

This paper reports a nontoxic, soft and electroactive hydrogel made with polyvinyl alcohol (PVA) and cellulose nanocrystal (CNC). The CNC incorporating PVA-CNC hydrogels were prepared using a freeze–thaw technique with different CNC concentrations. Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy results proved the good miscibility of CNCs with PVA. The optical transparency, water uptake capacity and mechanical properties of the prepared hydrogels were investigated in this study. The CNC incorporating PVA-CNC hydrogels showed improved displacement output in the presence of an electric field and the displacement increased with an increase in the CNC concentration. The possible actuation mechanism was an electrostatic effect and the displacement improvement of the hydrogel associated with its enhanced dielectric properties and softness. Since the prepared PVA-CNC hydrogel is nontoxic and electroactive, it can be used for biomimetic soft robots, actively reconfigurable lenses and active drug-release applications.

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RHEOLOGY OF WATER-SOLUBLE MONOMERS AND THEIR MIXTURES

Вестник Тверского государственного университета. Серия: Химия ◽

10.26456/vtchem2021.2.11 ◽

2021 ◽

pp. 113-122

Author(s):

Межлум Левонович Ерицян ◽

Армен Мамиконович Арустамян ◽

Валентина Межлумовна Мависакалян

Keyword(s):

Acrylic Acid ◽

Spatial Structure ◽

Polyvinyl Alcohol ◽

Aqueous Solutions ◽

Functional Groups ◽

Polyacrylic Acid ◽

Relative Viscosity ◽

Water Soluble ◽

Simultaneous Formation

Исследована реология водных растворов полиакриловой кислоты, полиакриламида, поливинилового спирта, сополимера акриловой кислоты с акриламидом, a также смесeй водных растворов этих полимеров. В результате образования ассоциатов между функциональными группами уаказанных полимеров значительно повышается относительная вязкость их водных растворов. Установлено, что при температуре 95C в водных растворах полиакриламида и сополимера акриловой кислоты с акриламидом происходит интенсивное выделение аммиака с одновременным образованием полимера пространственной структуры. The rheology of aqueous solutions of polyacrylic acid, polyacrylamide, polyvinyl alcohol, copolymer of acrylic acid with acrylamide, as well as mixtures of aqueous solutions of these polymers was investigated. As a result of the formation of associates between the functional groups of the polymers indicated, the relative viscosity of their aqueous solutions significantly increases. It was established that at a temperature of 95°C in aqueous solutions of polyacrylamide and a copolymer of acrylic acid and acrylamide, there is an intense release of ammonia with simultaneous formation of a polymer of spatial structure.

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PREPARATION OF CARBOXYMETHYL CELLULOSE AND POLYVINYL ALCOHOL (CMC/PVA) HYDROGELS USING FREEZE−THAW PROCESSES FOR ADSORPTION OF Zn2+ AND Cu2+

Cellulose Chemistry and Technology ◽

10.35812/cellulosechemtechnol.2021.55.36 ◽

2021 ◽

Vol 55 (3-4) ◽

pp. 375-383

Author(s):

NEDA PAVANDI ◽

ELHAM TAGHAVI ◽

NAVIDEH ANARJAN

Keyword(s):

Polyvinyl Alcohol ◽

Carboxymethyl Cellulose ◽

Numerical Optimization ◽

Polynomial Equations ◽

Swelling Ratio ◽

Process Variables ◽

Freeze Thaw ◽

Gel Fraction ◽

Zero Order Kinetics ◽

Order Polynomial

"The preparation of carboxymethyl cellulose and polyvinyl alcohol (CMC/PVA) composites is proposed in the present work. The CMC/PVA hydrogels were prepared using freeze−thaw processes. The effects of freezing time and of the number of freeze−thaw cycles on the swelling ratio and gel fraction of achieved hydrogels were evaluated using response surface methodology. The multiple regression analysis suggested second order polynomial equations as models for predicting changes of the studied hydrogel characteristics by selected process variables, with relatively high coefficients of determination (R2 > 0.82). The numerical optimization suggested that freezing the polymer solutions for 5 h and repeating the freeze−thaw process for 5 times would give the most desirable hydrogels with highest either swelling ratio or gel fraction. Remarkably, the ion adsorption studies showed that the adsorption of Cu2+ and Zn2+ ions by the hydrogels obeys zero order kinetics and the high capability of the produced optimum hydrogels to adsorb selected ions from synthetic waste was confirmed."

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Physical Properties of Polyvinyl Alcohol Prepared from Freeze-Thaw Cycled Gel

Sen i Gakkaishi ◽

10.2115/fiber.72.p-387 ◽

2016 ◽

Vol 72 (8) ◽

pp. P-387-P-392

Author(s):

TAKAHIKO NAKAOKI

Keyword(s):

Polyvinyl Alcohol ◽

Physical Properties ◽

Freeze Thaw

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Understanding the Colloidal Behaviour or 45S5 Bioactive Glass Particles to Obtain Bioactive-Glass Based Composite Coatings by EPD

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.654.15 ◽

2015 ◽

Vol 654 ◽

pp. 15-19

Author(s):

Sandra Cabanas-Polo ◽

Aldo R. Boccaccini

Keyword(s):

Polyvinyl Alcohol ◽

Bioactive Glass ◽

Functional Groups ◽

Polyacrylic Acid ◽

Glass Phase ◽

Composite Coatings ◽

Surface Reactions ◽

Colloidal Processing ◽

And Control ◽

Soft Composite

The interaction between bioactive glass particles and polymers with different functional groups has been established in this work to better understand and control the colloidal processing of the bioactive glass phase. Cationic polyvinylpyrrolidone (PVP), anionic polyacrylic acid (PAA) and neutral polyvinyl alcohol (PVA) were selected and the surface reactions in alcoholic media and between bioactive glass particles and polymers were considered. All three polymers were successfully employed to obtain soft composite coatings incorporating bioactive glass particles.

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