Multiporous microstructure for enhancing the water absorption and swelling rate in poly(sodium acrylic acid) superabsorbent hydrogels based on a novel physical and chemical composite foaming system

Abstract

In this article, we report a novel physical and chemical composite foaming system, which was used to successfully prepare high‐performance and low‐cost composite superabsorbent [poly(sodium acrylic acid) (PAA–Na)] hydrogels based on acrylic acid by free‐radical polymerization in a water bath under a nitrogen atmosphere without the use of any organic solvents. The prepared hydrogels showed superabsorbent properties, high water‐absorption abilities and swelling rates, a lighter packing density, and a multiporous microstructure. Fourier transform infrared spectroscopy and scanning electron microscopy revealed that the sodium dodecyl sulfate surfactant, sodium bicarbonate chemical foaming agent, and 1,1,2‐trifluorotrichloroethane physical foaming agent were evenly distributed and grafted onto the PAA–Na matrix. Water‐absorption, swelling rate, and packing density testing confirmed that the superabsorbent had a high water‐absorption ability and swelling rate and a lighter packing density. Furthermore, we investigated the effects of different foaming agents, including chemical and physical foaming agents, on the swelling and water‐retention capabilities of the superabsorbent hydrogels (SAHs).The results show that the combination of these foaming agents significantly improved the water‐absorbing capacity. With the help of these foaming agents, we obtained PAA–Na hydrogels without any organic solvents for posttreatment or special porogens; this is an environmentally beneficial way to prepare SAHs for hygiene and biomedical products. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44149.

Preparation of Poly (Allylthiourea-Co-Acrylic Acid) Derived Carbon Materials and Their Applications in Wastewater Treatment

“…To elaborate further, PAT–PAC-70 had the best ability to hold water, followed by PAT–PAC-50, and PAT–PAC-30. AA contained the hydrophilic groups –COOH, which could form hydrogen bonds with water molecules or ionize in a basic environment, while AT units were hydrophobic [ 23 ]. Thus, it can be deduced that PAT–PAC hydrogels were synthesized successfully.…”

“…With further increases in the carbonization temperature to 400 °C, the C=O vibration was completely invisible and the C=C vibration split into two peaks at 1653 and 1600 cm −1 , indicating that two different conjugated C=C systems may have been produced and the residual C=O groups were not detectable. Moreover, the peak of O–C=O at 1167 cm −1 and 1239 cm −1 [ 7 , 23 ] merged into a new single peak (1203 cm −1 ), which ultimately disappeared at the highest carbonization temperature of 400 °C. Therefore, it can be concluded that pyrolysis was accelerated under the higher carbonization temperature, leading to the loss of the functional groups (i.e., O–H, N–H, C=N, –COO–, and C=O, etc.)…”

Structural Modifications of Sodium Polyacrylate-Polyacrylamide to Enhance Its Water Absorption Rate

“…Researchers also tried to innovate on the foaming system. Si et al successfully prepared a porous sodium polyacrylate with a new foaming system [23]. Qing et al [24] studied the effect of two foaming techniques (gas blowing and porosigen) on the physical and swelling properties of the polymers.…”

Desenvolvimento de hidrogéis neutros e iônicos para a remoção de água livre do biodiesel

“…Durante a reação de polimerização são introduzidas substâncias formadoras de poros. Um exemplo é a utilização de bicarbonato de sódio durante a síntese do hidrogel de poli(ácido acrílico) (CHEN et al, 2016). Em meio ácido, ocorre a protonação do bicarbonato, que é convertido a ácido carbônico (Equação 2.3).…”

“…Visando à aplicação comercial, uma característica desejada é a rápida difusão de água para dentro da estrutura tridimensional. Um grupo de pesquisa sintetizou um hidrogel poroso de acrilato de sódio (CHEN et al, 2016). Para tanto, bicarbonato de sódio e outros reagentes foram utilizados para a formação de poros na estrutura do hidrogel.…”