Pagliacci . Ruggero Leoncavallo

Hydrophobic porous copolymer resins based on divinylbenzene (DVB) and acrylonitrile (AN) could be prepared as directly swellable in water by using purified DVB (98.8%) and technical DVB (79.3%) in the presence of 1,2-dichloroethane as porogen. Compared with the resins based on DVB and methyl acrylate (MA/DVB resins), the AN/DVB resins thus obtained are waterswellable over a wider range of copolymer compositions, and the swelling ability of the AN/DVB resins in water was further confirmed by investigating the water-swelling behavior of the AN/DVB resins undergoing solvent treatment. The copolymer composition (AN and DVB contents) of the resins and the property of the porogen affect the waterswellable behavior of the AN/DVB resins profoundly. The results in this paper provide additional evidence to support the hypothesis that the swelling ability of a hydrophobic porous copolymer in water originates from the existence of the inner stresses in the strained polymer network of the resins and the weak interaction between polymer and water that is negligible in the case of a conventional hydrophobic polymer.

Section: Resultsmentioning

confidence: 99%

Water‐swellable hydrophobic porous copolymer resins based on divinylbenzene and acrylonitrile. I. Water‐swelling behavior

Tang

Wei

Yan

2004

“…As a porous copolymer, the swelling of the EGDM/DVB resins is a very complex process that must be discussed by considering the expansion of the permanent pores, and the “reopening” of the collapsed pores 12–14. However, the gel phase of the porous copolymers, as we know, is composed of highly crosslinked microgel particles that are closely linked together by fewer crosslinked networks to form a continuous phase 15–18. In this case, any expansion of the permanent or the collapsed pores is not a separate course, and it must be accompanied by either the deformation of the gel phase or the relaxation of the crosslinked network chains.…”

Section: Resultsmentioning

confidence: 99%

Water‐swelling behavior of hydrophobic porous copolymer resins composed of two kinds of crosslinkers

Zhao

Wang

Yan

2004

ABSTRACT:Hydrophobic, but water-swellable, porous copolymer resins composed of divinylbenzene (DVB) and ethylene glycol dimethacrylate (EGDM) or ethylene glycol diacrylate (EGDA) were prepared by using purified DVB (98.8%) in the presence of toluene as porogen. The EGDM/ DVB resins thus obtained, whose polarity was nearly identical to that of the resins based on DVB and methyl methacrylate (MMA) at the same DVB levels, were water-swellable by direct contact with water up to a DVB content of 64%, whereas the latter did not swell in water at any DVB levels. EGDA is also hydrophobic, but with a polarity greater than that of EGDM. As a result, the EGDA/DVB resins were more water swellable than EGDM/DVB resins, and could also be prepared as water-swellable materials by using technical DVB (79.3%), besides the use of the purified DVB. All these results were explained on the basis of the network rigidity (crosslinking density) and the polymer polarity of the resins that were formed in the presence of a well-solvating porogenic solvent.

“…Further details on morphology control in resins prepared by suspension polymerizations are available in the literature. [22][23][24][25] In addition, the type or amount of the pore-forming agent or porogen is important in the resulting pore structure and morphology of the polymer.…”

Section: Introductionmentioning

confidence: 99%

Production of macroporous resins for heavy‐metal removal. I. Nonfunctionalized polymers

Ortíz-Palacios

Cardoso

Manero

2007

The aim of this work was the synthesis of macroporous resins with large specific surface areas through the use of organic solvents (known as porogens or pore-forming agents) for applications in hexavalent chromium (Cr 16 ) removal operations. The synthesis of these materials by suspension polymerization allowed the generation of macroporous structures. The comonomers 4-vinylpyridine and divinylbenzene were considered in different ratios. Poly(vinyl alcohol) was used as a suspension agent in a mixture of toluene and hexane. The materials produced were characterized with Fourier transform infrared spectroscopy, elemental analysis, thermogravimetry, nitrogen adsorption, and scanning electron microscopy. The macroporous resin with the largest surface area (130 m 2 /g) was thermally stable up to 3008C and had a structure that included spherical domains with a mean diameter of 68 lm, uniform porosity, and expected high sorption capability. The sorption properties of the resins were evaluated for applications in water-treatment operations to eliminate Cr 16 ions at a pH near 7. The advantages of these materials were their high removal capability, high selectivity, and fast adsorption kinetics at a pH 6.5. An aqueous solution of 4 ppm K 2 Cr 2 O 7 was used to quantify the Cr 16 content by ultraviolet-visible spectroscopy. A remarkable sorption level (94%) of chromate ions (Cr 16 ) was obtained during a 15-h period for the resin with the highest pyridine group content.