Superabsorbent resin of acrylic acid/ammonium acrylate copolymers synthesized by ultraviolet photopolymerization

A new method of synthesizing a superabsorbent resin (SAR) from an acrylic acid/ammonium acrylate copolymer by direct UV photopolymerization was studied. The effects of the degree of neutralization of acrylic acid, the photoinitiators, the crosslinking agents, and the UV‐light exposure time on the water absorbency (Q) were investigated. The results showed that Q of an SAR based on Irgacure 1700 or Irgacure 1800 and Irgacure 651 was high, reaching about 1200 mL/g, but under the same conditions, Q was low for an SAR based on other photoinitiators. The UV absorption spectrum proved that the photoinitiators matched the UV light source. Among the crosslinking agents, N,N′‐methylene bisacrylamide was more efficient than the others at a small concentration and a high value of Q. ¹³C‐NMR spectrometry was used to identify the mechanism of the crosslinking reaction through the esterification of hydroxyethyl acrylate (HEA) and 2‐hydroxypropyl acrylate with carboxylic acid group in acrylic acid/ammonium acrylate copolymerization, but the efficiency of the crosslinking reaction by esterification was lower than that of the copolymerization of vinyl groups in the crosslinking agent. Q of the acrylic acid/ammonium acrylate copolymer for the SAR reached 1255 mL/g under certain conditions (degree of neutralization of acrylic acid = 75%, Irgacure 651 concentration = 0.2 wt %, [HEA] = 0.2 wt %, exposure time = 10 min). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 546–555, 2005     

Crosslinking reaction of polyacrylate soap‐free hydrosol with zirconium chelate

The crosslinking reaction mechanism of polyacrylate copolymer (monomer mass ratio of methyl methacrylate/butyl acrylate/acrylic acid = 48.77:46.69:4.54) hydrosol with triethanolamine chelate of zirconium isopropyloxide was studied with IR spectroscopy, NMR spectroscopy, differential scanning calorimetry, and ultraviolet spectroscopy. The instrumental analyses on the copolymer mixture heated at different temperatures were investigated, and we proved that the crosslinking adduct had amino groups that were provided by the chelate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3605–3609, 2004     

Effects of carboxyl group on the ambient self‐crosslinkable polyacrylate latices

Ambient curable carbonyl functional acrylic latices were synthesized by incorporating diacetone acrylamide as functional monomer into acrylic copolymer, adipic acid dihydrazide (ADH) was used as curing agent. In this work acrylic acid (AA) and acrylic acid homopolymer (PAA) were used to facilitate the crosslinking reaction. We found that the properties of latex film were different when use AA and PAA as the source of the carboxyl groups separately. The results from the characterization of carboxyl groups of the latex particles demonstrated that the distribution of the carboxyl group on the latex particle surface is optimal for the crosslinking reaction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3948–3953, 2007     

Superabsorbent hydrogel of acrylic acid/potassium acrylate copolymers by ultraviolet photopolymerization: Synthesis and properties

Synthesis of superabsorbent hydrogel (SAHG) of acrylic acid‐potassium acrylate copolymer by direct Ultraviolet (UV) photopolymerization is a new method. The effects of degree of neutralization of acrylic acid (AA), photoinitiators, crosslinking agents, and exposure time of UV light on water absorbent properties were investigated. The results showed that the water absorbency (Q) and the salt solution (NaCl, 0.9%) absorbency (Qs) of SAHG, based on Irgacure 651, are high, reaching about 1400 and 130 mL/g, respectively. UV absorption spectrum proved that peak of UV absorption of Irgacure 651 matched the UV light source we used. Among the crosslinking agents, N,N′‐methylene bisacrylamide is more efficient than others, because of its very small content and high Q. ¹³C NMR spectrometry was used to identify the mechanism of crosslinking reaction through esterification of hydroxyethyl acrylate (HEA) and 2‐hydroxypropyl acrylate (HPA) with carboxylic acid group in acrylic acid‐ammonium acrylate copolymerization, but efficiency of crosslinking reaction by esterification was lower than that of copolymerization of vinyl group in crosslinking agent. The Q of acrylic acid‐potassium acrylate copolymer of SAHG reaches 1592 mL/g under the following conditions: degree of neutralization of acrylic acid is 80%, content of Irgacure 651 is 0.25 wt %, content of HEA is 0.2 wt %, and exposure time is 10 min. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1181–1187, 2006     

Studies on acrylate copolymer soap‐free waterborne coatings crosslinked by metal ions

Acrylate copolymers containing hydrophobic monomers (methyl methacrylate, butyl acrylate, styrene, or divinyl benzene) and hydrophilic monomer (acrylic acid) were synthesized by solution polymerization, and neutralized to form the soap‐free hydrosol. The waterborne coating was prepared from the hydrosol crosslinked by M(NH₃) (M²⁺ was Zn²⁺ , Cu²⁺, Ni²⁺ or Co²⁺). ¹³C‐NMR analysis was used to identify the copolymer. The result of GPC showed that the molecular weight of the copolymer was within the range of thermosetting resin for coating. The factors affecting the crosslinking degree of the coating films were studied by DSC and gravimetric analysis. The results indicated that the appropriate crosslinking agent was Zn(NH₃), and the optimum curing condition was heating at 80°C for 30 min. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 91–96, 1999     

Preparation of acrylic copolymer latex modified by fluorine,silicon, and epoxy resin

A series of modified acrylic copolymer latices have been prepared through a semicontinuous emulsion copolymerization process with a variety of hydrocarbon monomers and (perfluoroalkyl) methyl methacrylate, vinyltriethoxysilicone, and phenol‐formaldehyde epoxy resin. The composition of copolymer was analyzed by fluoride ion selective electrode analysis, ¹⁹F NMR, FTIR, crosslinking degree determination, and epoxy‐acetone method. The results showed that the fluorine monomer, silicon monomer and epoxy resin had copolymerized with acrylic monomers. The optimum mass ratio between the curing agent TEA and epoxy resin was 1.36 : 6. The determination results of stabilities (electrolyte stability, freeze‐thaw stability, high temperature stability and mechanical stability) of latices showed that the incorporation of fluorine monomer and silicon monomer improved freeze‐thaw stability and mechanical stability, whereas the epoxy resin did not have obvious effect on the stabilities. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polyurethane–polyaniline conducting graft copolymer with improved mechanical properties

The crosslinking effects on the mechanical and electrical properties of a conducting copolymer obtained by grafting polyaniline on a carboxylated polyurethane were investigated. The synthesis and characterization of the polyurethane–polyaniline copolymer (PEUAPAN) were previously reported. The crosslinking process was carried out by reacting ethylenediamine with those polyurethane residual carboxylic groups not involved in the amide binding to the conducting chains. The insoluble material obtained (PEUAPANc) shows a marked elastomeric feature, as evidenced in stress–strain and stress–relaxation measurements. Although the crosslinked graft copolymer conductivity is lower than that of the pristine material, its variation during deformation cycles is reversible because the chain relaxation and viscous flow phenomena are drastically suppressed by the crosslinks. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2516–2521, 2003     

Preparation and properties of a salt‐resistant superabsorbent polymer

Crosslinked sodium polyacrylate was prepared by solution polymerization with N,N‐methylene‐bisacrylamide (bisAM) as crosslinking agent; it was subsequently surface‐crosslinked by ethylene glycol diglycidyl ether (EGDE) and then was modified with inorganic salt to obtain a superabsorbent with water absorbency in 0.9 wt % NaCl aqueous solution at atmosphere and applied pressure (P ≈ 2 × 10³ Pa) of 55 and 20 g.g^?1, respectively. Moreover, it also had excellent hydrogel strength. The effects of reaction temperature, reaction time, neutralization degree (ND) of acrylic acid, amount of initiator, crosslinking agent, and surface‐crosslinking agent, mass ratio of inorganic salt to initial superabsorbent, molar ratio of sodium aluminate (NaAlO₂) to potassium dihydrogen hyphosphate (KH₂PO₄) on water absorbency (WA) in 0.9 wt % NaCl aqueous, and the hydrogel modulus were investigated and optimized. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2532–2541, 2004     

双亲嵌段共聚物PSt-b-P(St-alt-MA)-b-PAA的自组装行为

以三硫代碳酸二(α, α'-二甲基-α-乙酸)酯(BDATC)为链转移剂, 以苯乙烯、马来酸酐、丙烯酸为原料, 通过可逆加成-断裂链转移(RAFT)合成了双亲嵌段共聚物PSt-b-P(St-alt-MA)-b-PAA。通过选择性溶剂N, N-二甲基甲酰胺(DMF)诱导聚合物进行自组装, 利用紫外-可见光光度仪、纳米激光粒度仪详细研究了共聚物中亲疏水嵌段长度、初始浓度、体系pH值对聚合物自组装行为的影响。通过化学交联的方法制备得到了聚合物交联胶束, 利用透射电镜表征了形貌与尺寸, 研究明确了其形状和尺寸的稳定性。结果表明, 上述因素均会影响共聚物的自组装行为和自组装胶束的形态, 经乙二胺交联得到的交联自组装胶束平均粒径为145.4nm, 并具有良好的形状和尺寸稳定性。     

Ultraviolet curable dry polymer films from emulsion polymers

Low levels of functional acrylic monomers were incorporated into a core‐shell acrylic copolymer by seeded emulsion polymerization. The increase in glass transition temperature, T_g, from DSC measurement has showed that although certain amount of crosslinking reactions have occurred during the polymerization and isolation of the copolymer, the dried copolymer films could undergo further curing by UV irradiation. The structure and amount of the functional monomer, concentration of photoinitiator, and the extent of UV exposure have exerted significant influence on the T_g of the dry copolymer films. Because of the relatively low level of incorporated unsaturation, there was no significant change in FTIR during the curing of the film. Further, crosslinking of the copolymer film induced by UV irradiation has significantly increased the resistance to swelling in alkaline solution, although the gel content remained the same. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2317–2322, 2006     

Alkoxysilane‐functionalized acrylic copolymer latexes. I. Particle size,morphology, and film‐forming properties

Via the conventional emulsion copolymerization of acrylic monomers and vinyl‐containing alkoxysilane monomers with three siloxane groups, siloxane groups were added to acrylic copolymers to make alkoxysilane‐functionalized acrylic copolymer latexes. In producing stable polymer latexes, seeded polymerization was superior to the other two processes, batch and continuous addition polymerization. The experimental results showed that vinyltriethoxysilane–acrylic copolymer latexes were capable of film forming. In contrast, the incorporation of methacryloxypropyl trimethoxysilane gave rise to the formation of highly crosslinked acrylic copolymer latexes, which had poor film‐forming properties. Relatively small monodispersed particles with particle sizes of less than 100 nm were formed. These particles had a core–shell structure, although some of them were asymmetric. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 954–960, 2004     

Effect of naphthyl curing agent having thermally stable structure on properties of UV-cured pressure sensitive adhesive

Pressure sensitive adhesives (PSAs) with higher thermal stability were synthesized by crosslinking acrylic copolymer with naphthyl curing agent. The acrylic copolymer was synthesized for a base resin of PSAs by solution polymerization of 2-ethylhexyl acrylate, ethyl acrylate, and acrylic acid with N,N′-azobisisobutyronitrile as an initiator. The acrylic copolymer was further modified with glycidyl methacrylate to have the vinyl groups available for UV curing. Thermal stability of acrylic PSAs was improved noticeably with increasing naphthyl curing agent content and UV dose mainly due to the extensive formation of crosslinked structure in the polymer matrix. Although the peel strength decreased with UV curing of acrylic polymer, a proper balance between the thermal stability and the adhesion performance of PSAs was obtained by controlling the UV curing with naphthyl curing agent content and UV dose.     

Synthesis of superabsorbent resin by ultraviolet photopolymerization

Synthesis of superabsorbent resin (SAR) was achieved by a new method, that of direct UV photopolymerization, and in particular the synthesis of a SAR of acrylic acid–potassium acrylate copolymer by UV photopolymerization was investigated. Influences of ratio (mol) of acrylate monomer to acrylic acid monomer, photoinitiators, crosslinking agents, and exposure time of UV light on the water‐absorbent properties were investigated. The results showed that the water absorbency (Q) of SAR based on Irgacure 1700 or Irgacure 1800 was 545–530 mL/g, but under the same conditions Q was 450 mL/g for the SAR based on Irgacure 651. N,N′‐Methylene bisacrylamide, hydroethyl acrylate, and glycerol were used as crosslinking agents, of which N,N′‐methylene bisacrylamide was the most effective. It crosslinked the molecular chains through attending the copolymerization with acrylic acid (AA) and potassium acrylate. When the exposure time was 5 min, the value of Q was 1368 mL/g (the content of N,N′‐methylene bisacrylamide was 100 ppm). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1618–1624, 2004     

Characterization of crosslinked ethylene—Vinylacetate copolymers

Two types of ethylene-vinylacetate copolymers, containing 16% and 9% of vinylacetate, respectively, were crosslinked with dicumyl peroxide in a Brabender plastograf. The time of the torque maximum was proportional to the degree of crosslinking. The degree of crosslinking was determined by extraction and depended on the concentration of the crosslinking agent and of vinylacetate in the copolymer, and on the crosslinking temperature and time. It was found by DSC and by solid-state CP-MAS ¹³C NMR that with the progress of crosslinking the crystalline phase of the copolymers changed to the amorphous phase. Crosslinking took place mostly on the acetate groups.     

Synthesis of water‐reducible acrylic–alkyd resins based on modified palm oil

Water‐reducible acrylic–alkyd resins were synthesized from the reaction between monoglycerides prepared from modified palm oil and carboxy‐functional acrylic copolymer followed by neutralization of carboxyl groups with diethanolamine. Modified palm oil was produced by interesterification of palm oil with tung oil at a weight ratio of 1 : 1, using sodium hydroxide as a catalyst, whereas carboxy‐functional acrylic copolymer was prepared by radical copolymerization of n‐butyl methacrylate and maleic anhydride. The amount of acrylic copolymer used was from 15 to 40% by weight, and it was found that homogeneous resins was obtained when the copolymer content was 20–35 wt %. All of the prepared water‐reducible acrylic–alkyd resins were yellowish viscous liquids. Their films were dried by baking at 190°C and their properties were determined. These films showed excellent water and acid resistance and good alkali resistance. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1170–1175, 2005     

Crosslinking of isocyanate functional acrylic latex with telechelic polybutadiene. I. Synthesis and characterization

An ambient curable isocyanate functional acrylic latex was synthesized by incorporating dimethyl meta-isopropenyl benzyl isocyanate (TMI®), an isocyanate monomer, into styrene/n-butyl acrylate copolymer. An artificial latex of amino-terminated telechelic polybutadiene was prepared and blended with the acrylic latex as a curing agent. The isocyanate content in the blended latex was determined by titration and FTIR measurements. The latex blend properties, in terms of particle size and latex viscosity, and the latex film properties, in terms of stress–strain behavior and solvent swelling behavior, showed no significant change after 30 days' storage of the latex blend at 50°C. The good storage stability was attributed to the stable nature of the latex blend in which there was little chance for the isocyanate-containing particles to come into contact with the curing agent particles, thus preventing premature contact of the acrylic chains with the telechelic chains. The reactivity of different functional groups in the telechelic polymer was studied; the amino group was found to be the most reactive toward the TMI. In addition, a shorter chain telechelic crosslinker was found to result in a higher degree of crosslinking, but this was more intraparticle than interparticle in nature. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 965–975, 1998     

Synthesis and properties of acrylic‐based superabsorbent

Acrylic‐based superabsorbent polymers with partial‐neutralized acrylic acid were synthesized by inverse suspension polymerization. The effects of reaction parameters, including the concentration of crosslinking agent and initiator, the neutralization degree of monomer, the monomer concentration, and phase ratio of a system, on the water absorption have been investigated. Furthermore, to improve the properties of salt‐resistance and antielectrolyte for the polymer, acrylamide monomer containing nonionic and hydrophilic groups was introduced into the system, which can suppress the salt effect and homoion effect. The water absorption Q^5/3 is proportional to the reciprocal of ionic strength, 1/S, which follows Flory's elasticity gel theory. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 619–624, 2004     

Metal complexation studies of amylopectin‐graft‐poly[(N,N‐dimethylacrylamide)‐co‐(acrylic acid)]: a biodegradable synthetic graft copolymer

Synthesis of amylopectin‐graft‐poly[(N,N‐dimethylacrylamide)‐co‐(acrylic acid)] was carried out using solution polymerization technique with potassium persulfate as the initiator. The graft copolymer was characterized by measuring molecular weight using size exclusion chromatography, thermal analysis and Fourier transform infrared (FTIR) spectroscopy. The synthetic graft copolymer was used for the removal of some potentially toxic metal ions, Cu(II), Zn(II) and Ni(II), from their aqueous solutions. Various operating parameters like the amount of adsorbent, solution pH, contact time and temperature were studied. The adsorption data were well described by the pseudo‐second‐order and Langmuir isotherm models. Metal complexation studies were carried out experimentally using cyclic voltammetry and UV‐visible and FTIR spectroscopies. The metal complex structure was also studied theoretically using density functional theory with the Gaussian 09 program and the geometry of the complex structure was optimized. The metal complexation ability of the graft polymer was in the order Cu(II) > Ni(II) > Zn(II). Calculation of the various thermodynamic parameters was also done. The negative value of free energy change indicates the spontaneous nature of the adsorption. © 2015 Society of Chemical Industry     

Functionally‐modified egg white albumen hydrogels

Hydrogels were prepared by using egg white albumen (EWA) before and after chemical modification of its lysyl residues with ethylenediamine tetraacetic dianhydride (EDTAD) to incorporate carboxylic groups. This resulted in an increase in swelling ratio of the EWA hydrogels. The swelling ratio increased dramatically in deionized water substantially, more than in pH 7.4 buffer solution. The effects of medium pH, temperature and swelling were investigated, along with crosslinking of the gel network by glutaraldehyde (GLA), as well as acetone treatment. The gels denatured by acetone showed an insignificant increase in swelling ratio for the gels crosslinked with GLA during gel preparation, which is in contrast to the gels crosslinked subsequent to gel formation. The swelling behavior was positively affected by temperature and time. However, an insignificant effect of pH was observed due to electrostatic screening of the carboxylic groups by sodium ions in the buffer solution. Availability of various functional groups on EWA has resulted in adsorption of metals (Cu⁺² ions) and non‐metals (PO₄^?2 anions). Copyright © 2004 Society of Chemical Industry     

丙烯酸-丙烯酸钠自交联型高吸水性树脂的合成及性能研究

采用逆相悬浮法合成丙烯酸－ 丙烯酸钠自交联型高吸水性聚合物,研究了丙烯酸中和度、交联剂、引发剂、单体纯度、反应时间、反应温度等因素对共聚物吸水性能的影响。