Synthesis and properties of carboxymethyl cellulose‐graft‐poly(acrylic acid‐co‐acrylamide) as a novel cellulose‐based superabsorbent

A new cellulose‐based superabsorbent polymer, carboxymethyl cellulose‐graft‐poly(acrylic acid‐co‐acrylamide), was prepared by the free‐radical grafting solution polymerization of acrylic acid (AA) and acrylamide (AM) monomers onto carboxymethyl cellulose (CMC) in the presence of N,N′‐methylenebisacrylamide as a crosslinker with a redox couple of potassium persulfate and sodium metabisulfite as an initiator. The influences of reaction variables such as the initiator content, crosslinker content, bath temperature, molar ratio of AA to AM, and weight ratio of the monomers to CMC on the water absorbency of the carboxymethylcellulose‐graft‐poly(acrylic acid‐co‐acrylamide) copolymer were investigated. The copolymer's structures were characterized with Fourier transform infrared spectroscopy. The optimum reaction conditions were obtained as follows: the bath temperature was 50°C; the molar ratio of AA to AM was 3 : 1; the mass ratio of the monomers to CMC was 4 : 1; and the weight percentages of the crosslinker and initiator with respect to the monomers were 0.75 and 1%, respectively. The maximum water absorbency of the optimized product was 920 g/g for distilled water and 85 g/g for a 0.9 wt % aqueous NaCl solution. In addition, the superabsorbent possessed good water retention and salt resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1382–1388, 2007     

Synthesis,characterization, and flocculation performance of anionic polyacrylamide P (AM‐AA‐AMPS)

In this study, a kind of anionic polyacrylamide (P(AM‐AA‐AMPS)) was synthesized using acrylamide (AM), acrylic acid (AA), and 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS) under ultraviolet (UV) irradiation. The conditions of the polymerization reaction such as monomer mass ratio, solution pH value, EDTA concentration and urea concentration were investigated by using the single factor approach and an L₁₆ (4⁵) orthogonal array. The structure and morphologies of the copolymer were determined by nuclear magnetic resonance spectrometer (NMR), infrared spectrometer (IR) and scanning electron microscope (SEM). The results show P(AM‐AA‐AMPS) with the intrinsic viscosity of 1.5 × 10³ mL g^?1 was synthesized at optimal conditions: mass ratio, m(AM) : m(AA) : m(AMPS) of 70 : 10 : 10, pH value of 9.0, EDTA concentration of 0.10% and urea concentration of 0.20%. In addition, P(AM‐AA‐AMPS) had better flocculation efficiency than commercial PAM in sludge dewatering experiment; the minimum filter cake moisture content could be reduced to 65.1%. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of acrylic acid and AMPS cointercalated layered double hydroxide and its application for superabsorbent

This article reports the cointercalation of acrylic acid (AA) and 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) in the interlayer region of Mg₂Al layered double hydroxide (LDH) and the application of this inorganic–organic composite material in the field of water superabsorbent. The monomers of AA and AMPS were cointercalated into galleries of Mg₂Al−LDH (denoted as AA−AMPS/LDH) with various molar ratios by ion‐exchange method, which was confirmed by powder X‐ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), and elemental analysis. The polymer‐based superabsorbent was prepared through in situ free‐radical aqueous copolymerization of AA and AMPS, with AA−AMPS/LDH as additive, N,N′‐methylenebisacrylamide (NMBA) as crosslinker and potassium persulfate (KPS) as initiator. The composition of this poly(AA‐co‐AMPS)/LDH was demonstrated as a good water superabsorbent. The LDH content, water absorbency, thermal stability, and swelling rate of this superabsorbent were also investigated in detail. Results showed that the incorporation of a 5 wt % AA−AMPS/LDH into polymer matrix increased its water absorbency significantly by 27.7% (in water) and by 51.5% (in 0.9 wt % NaCl solution). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Experimental research of hydroquinone (HQ)/hexamethylene tetramine (HMTA) gel for water plugging treatments in high‐temperature and high‐salinity reservoirs

Polymer gel, as a water plugging treatment agent, has been successfully used in enhanced oil recovery (EOR) of mature oil fields. A new thermal‐resistance and salt‐tolerance polymer gel was developed based on HPAM and HQ/HMTA under the condition of high‐temperature (100.8 °C) and high‐salinity (up to 19.8 × 10⁴ mg/L and Ca²⁺&Mg²⁺ 0.8 × 10⁴ mg/L). The influence factors of gelling performance and coreflood performances were studied, the microstructure of the gel was observed with the environmental scanning electron microscopy, and gelation mechanism was proposed to illuminate the detailed gelation process. The gelation time decreases and the gel strength increases with the increase of polymer concentration, crosslinker concentration, or temperature. Although shearing had a negative effect on the viscosity of gelling solution, the gel strength, and the stability of gel have not been affected. The gelling solution has a good ability of injection and could selectively flow into high permeable zone. Additionally, the plugging rate increases and stays above 85% with the increase of the permeability or the gel strength. The microstructure of the gel confirms that the gel formed a three‐dimensional network structure. Based on the microstructure and the reaction process of the gel, a possible gelation mechanism is proposed. This study suggests that the gel system can be used in harsh reservoir conditions and the gelation time and gel strength can be controlled with adjusting the formation rate and the concentration of crosslinking agents. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44359.     

Homogeneous complex solution formed through interactions of poly(acrylamide‐co‐acrylic acid)/poly(acrylamide‐co‐dimethyldiallylammonium chloride) complex with M n+ hydration metal ions in aqueous media

A homogeneous complex solution, formed through inter‐polyelectrolyte complexation of poly(acrylamide‐co‐acrylic acid) (P(AM‐AA)) with poly(acrylamide‐co‐dimethyldiallylammonium chloride) (P(AM‐DMDAAC)) and interaction of the P(AM‐AA)/P(AM‐DMDAAC) complex with M ⁿ⁺ hydrated metal ion, was prepared and the structure and properties of the P(AM‐AA)/P(AM‐DMDAAC)/M ⁿ⁺ homogeneous complex solution were studied by UV spectrometry, dynamic light scattering and viscometry. The experimental results show that the homogeneous complex solution can be obtained by controlling the composition of the P(AM‐AA)/P(AM‐DMDAAC) complex and the M ⁿ⁺ metal ion content. Compared to the constituents, ie the P(AM‐AA) solution, the P(AM‐DMDAAC) solution and the P(AM‐AA)/P(AM‐DMDAAC) complex solution, the P(AM‐AA)/P(AM‐DMDAAC)/M ⁿ⁺ complex solution has a new peak at 270 nm in its UV spectrum, a larger hydrodynamic radius, and hence a higher solution viscosity, all of which indicate that there exist specific interactions between polymers and M ⁿ⁺ metal ions. These interactions lead to the formation of a network structure and hence an obvious increase not only in solution viscosity but also in resistance of the polymer solution to simple salts, to temperature changes and to shearing. © 2001 Society of Chemical Industry     

Influence of the initiator system on the spatial inhomogeneity in acrylamide‐based hydrogels

The effect of the initiator system used in the gel preparation on the spatial inhomogeneity in poly(acrylamide) (PAAm) and poly(N,N‐dimethylacrylamide) (PDMA) hydrogels was investigated by static light scattering and elasticity measurements. The hydrogels were prepared by free‐radical crosslinking copolymerization of the monomers acrylamide (AAm) or N,N‐dimethylacrylamide (DMA) with N,N′‐methylenebisacrylamide as a crosslinker. Two different redox‐initiator systems, ammonium persulfate (APS)–N,N,N′,N′‐tetramethylethylenediamine (TEMED) and APS–sodium metabisulfite (SPS), were used to initiate the gelation reactions. Compared to the APS–TEMED redox pair, no significant scattered light intensity rise was observed during the crosslinking polymerization reactions initiated by the APS–SPS system. It was found that both PAAm and PDMA gels are much more homogeneous when the APS–SPS redox pair was used as the initiator. The results are explained by the formation of shorter primary chains as well as the delay of the gel point in APS–SPS initiated gel formation reactions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3228–3237, 2007     

Synthesis and characterization of novel core‐shell magnetic nanogels based on 2‐acrylamido‐2‐methylpropane sulfonic acid in aqueous media

Ultrafine well‐dispersed Fe₃O₄ magnetic nanoparticles were directly prepared in aqueous solution using controlled coprecipitation method. The synthesis of Fe₃O₄/poly (2‐acrylamido‐2‐methylpropane sulfonic acid) (PAMPS), Fe₃O₄/poly (acrylamide‐co‐2‐acrylamido‐2‐methylpropane sulfonic acid) poly(AM‐co‐AMPS) and Fe₃O₄/poly (acrylic acid‐co‐2‐acrylamido‐2‐methylpropane sulfonic acid) poly(AA‐co‐AMPS) ‐core/shell nanogels are reported. The nanogels were prepared via crosslinking copolymerization of 2‐acrylamido‐2‐methylpropane sulfonic acid, acrylamide and acrylic acid monomers in the presence of Fe₃O₄ nanoparticles, N,N′‐methylenebisacrylamide (MBA) as a crosslinker, N,N,N′,N′‐tetramethylethylenediamine (TEMED) and potassium peroxydisulfate (KPS) as redox initiator system. The results of FTIR and ¹H‐NMR spectra indicated that the compositions of the prepared nanogels are consistent with the designed structure. X‐ray powder diffraction (XRD) and transmission electron microscope (TEM) measurements were used to determine the size of both magnetite and stabilized polymer coated magnetite nanoparticles. The data showed that the mean particle size of synthesized magnetite (Fe₃O₄) nanoparticles was about 10 nm. The diameter of the stabilized polymer coated Fe₃O₄ nanogels ranged from 50 to 250 nm based on polymer type. TEM micrographs proved that nanogels possess the spherical morphology before and after swelling. These nanogels exhibited pH‐induced phase transition due to protonation of AMPS copolymer chains. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Hydrosoluble copolymers of acrylamide‐(2‐acrylamido‐2‐methylpropanesulfonic acid). Synthesis and characterization by spectroscopy and viscometry

Hydrosoluble copolymers containing sulfonic acid groups incorporated into a macromolecule were synthesized. The group of polymers studied was obtained by free radical solution polymerization, using potassium persulfate as an initiator. The copolymerization of the monomers 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) and acrylamide (AA) was carried out at different pH values of the reaction medium of the monomer mix. The copolymers were characterized by proton nuclear magnetic resonance spectroscopy (¹H NMR) and Fourier transform infrared spectroscopy (FTIR). The viscosity behavior of the copolymers in NaCl solution showed a dependency on the pH of the reaction medium, with higher pH leading to lower viscosities. The acidic conditions of this medium affect the initiator decomposition rate, which is a probable cause of the viscosity variation, and the extent of decomposition increases with increasing pH. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 192–198, 2003     

Rheological properties of poly(ethylene glycol)/poly(N‐isopropylacrylamide‐co‐2‐acrylamido‐2‐methylpropanesulphonic acid) semi‐interpenetrating networks

For the increasing demands of multifunctional materials in applications such as drug delivery system, a pH‐ and temperature‐responsive polyelectrolyte copolymer gel system was studied using rheometry. Rheological properties, determined by plate–plate rheometry in oscillatory shear, of hydrogels formed by free radical initiated copolymerization of N‐isopropylacrylamide (NIPA) and 2‐acrylamido‐2‐methylpropanesulphonic acid (AMPS) in the presence of methylene bisacrylamide (MBAA) as crosslinker are compared with the properties of semi‐interpenetrating network (SIPN) polyelectrolyte gels made by incorporation of poly(ethylene glycol) with molar mass 6000 g mol^?1 (PEG6000). Based on our systematic studies for this PEG/SIPN system, the effects of initiator and crosslinker concentration, relative proportions of comonomer units in the main chains, PEG6000 content and temperature on viscoelastic properties, unusual high storage moduli at small strain for the SIPN were discussed. The SIPN gel with characteristics of PEG molecules as well as pH and temperature responsiveness from AMPS and NIPA units has potential application in drug delivery system design. Ice‐like rheological behavior of the PEG/AMPS‐NIPA SIPN gels at low temperature was first time reported and water remains homogeneous without phase separation in PEG/AMPS‐NIPA SIPN hydrogels at low temperature may be considered as an ideal candidate for water storage material. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Factors influencing absorbent properties of saponified starch‐g‐(acrylic acid‐co‐acrylamide)

Mixtures of acrylamide (AM) and acrylic acid (AA) were grafted onto gelatinized maize starch by using ceric ammonium nitrate (CAN) as an initiator. These graft copolymers were hydrolyzed with alkali to yield hydrogels. The effects of different reaction variables, such as the concentration of the initiator and crosslinker, initial dilution of monomers, gelatinization conditions of starch, and the ratio of AM and AA in the monomer feed, on the water absorption capacities of these hydrogels have been examined. Absorption increases on gelatinizing starch at a higher temperature for a longer time as smaller granules gelatinize only under these conditions. The higher proportion of AA in the monomer feed enhances absorption due to formation of polyelectrolyte. The optimum conditions for obtaining maximum water absorbency established in the present study are granular maize starch = 2.0 g; gelatinization temperature = 95°C; gelatinization time = 60 min; AM = 1.0 g; AA = 4.0 g; CAN = 0.008 mol/L; N,N′‐methylene bisacrylamide = 1%. The product so formed was saponified with NaOH and then precipitated in excess of methanol. The dried and finely powdered product showed the maximum water absorbency of 510 g/g. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2480–2485, 2000     

Homogeneous complex solution formed through interpolyelectrolyte complexation of poly(acrylamide–acrylic acid) with poly(acrylamide‐dimethyldiallylammonium chloride) in aqueous media

Interpolyelectrolyte complexation of two oppositely charged polymers in aqueous media is a new approach for modifying polymer solutions, especially for enhancing solution viscosity. In this paper, a homogeneous complex solution was prepared through complexation of poly(acrylamide–acrylic acid) [P(AM‐AA)] containing adjustable anionic content and poly(acrylamide–dimethyldiallylammonium chloride) [P(AM‐DMDAAC)] containing adjustable cationic content. The interactions between these two oppositely charged polymers and the viscosity of the complex solution were studied by means of visible spectrophotometry, UV spectrometry, fluorescence spectrometry, dynamic light scattering and viscometry. The experimental results show that a P(AM‐AA)/P(AM‐DMDAAC) homogeneous complex solution exhibits characteristics different from those of its constituents, due to intermacromolecular interactions. Compared to the two component polymer solutions, ie P(AM‐AA) solution and P(AM‐DMDAAC) solution, the complex solution has a new peak around 210 nm in its UV spectrum, lower fluorescence intensity and larger hydrodynamic radius, and hence higher solution viscosity. © 2000 Society of Chemical Industry     

耐盐型丙烯酸-丙烯酰胺接枝共聚高吸水树脂的合成及其性能研究

采用溶液聚合法,以丙烯酸(AA)和丙烯酰胺(AM)为单体,N,N＇-亚甲基双丙烯酰胺(NMBA)为交联剂,过硫酸钾(KPS)为引发剂.合成出丙烯酸-丙烯酰胺接枝共聚高吸水树脂.探讨了单体比[m(丙烯酸):m(丙烯酰胺)]、交联剂和引发荆用量、单体中和度及聚合温度对树脂吸水率的影响.IR光谱表明,丙烯酸和丙烯酰胺发生了接...     

Influence of hydrogen bonding interactions on the properties of ultraviolet‐curable coatings

Phenolic novolac type epoxy resin has been modified with acrylic acid (AA) and 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) to form ultraviolet‐curable coatings, and integrated performances of the coatings were evaluated. It was found that the hydrogen bonding interactions among the oligomers became stronger along with the increase of AMPS content, thus the oligomer viscosity and a variety of polymer properties were affected. The polar hydrogen bond donors significantly enhanced the adhesion strength and surface wetting behavior of the coatings. Meanwhile, hydrogen bonding interactions can also reinforce the three‐dimensional structure of the film as in polymeric state, which potentially increased its glass transition temperature and mechanical properties. Results of chemical resistance showed that coatings modified with moderate amount of AMPS could be completely removed in several minutes when exposed to alkali solution or anhydrous ethanol. With these attractive features, modified films had prospective applications in temporary protective coatings. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43113.     

Synthesis and characterization of functionalized acrylic‐acrylamide‐based superabsorbent gels

We have synthesized series of superabsorbent polymers (SAPs) by solution free radical polymerization of acrylic acid (AA), acrylamide (AM) with different functional monomers (FM). Three functional monomers including zwitterionic monomer [3‐(methacryloylamino) propyl] dimethyl (3‐sulfopropyl) ammonium (MPDSA), cationic monomer (3‐acrylamidopropyl) trimethylammonium chloride (APTAC) and anionic monomer 2‐acrylamidoglycolic acid monohydrate (AGAM) were selected to provide different charged groups on the superabsorbents. The effect of reaction parameters, such as degree of neutralization, content of initiator and crosslinker on the swelling capacity were assessed. The water absorbency of the superabsorbent were characterized in the distilled water, 0.9 wt % NaCl solution and the mixed solution containing 60 mg L^?1 CaCl₂ and 30 mg L^?1 MgCl₂, respectively. In addition, the swelling rate and water retention capacity in the soil were also investigated. Finally, the mechanism of different absorbency induced by the variety kinds of functional monomers was studied by XPS and FTIR, and tentative interpretation was presented as well. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Hydrophobically associating polyacrylamide derivatives with double bond for enhanced solution properties

A hydrophobically associating polyacrylamide with double bond P (AM‐MAA‐AMPS‐HDDE‐SA) (PAMAHS) has been synthesized by micellar copolymerization technique in mixed solvents (anhydrous ethanol and distilled water (1:10 by volume)) and characterized. The morphology and microstructure of PAMAHS copolymer observations show the formation of multilayer network‐like stacked structure, and the dissolution property and temperature resistance of the copolymer measurements show that PAMAHS has a good solubility and exhibits unique solution behavior. Due to the hydrophobic associations, the solution viscosity increases sharply when the polymer concentration exceeds a certain value. AFM confirms the existence of the polymer network structure in aqueous solution, and the enhancement of thermal stability of polymer is affirmed through TGA. Compared with the unmodified P (AM‐MAA‐AMPS‐SA) (PAMAS) copolymer, PAMAHS incorporation of capsaicin‐like monomer with biological activity is endowed with excellent antibacterial performance against Escherichia coli and Staphylococcus aureus. POLYM. ENG. SCI., 56:1203–1212, 2016. © 2016 Society of Plastics Engineers     

Poly(acrylic acid‐co‐acrylamide‐co‐2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid)‐grafted nanocellulose/poly(vinyl alcohol) composite for the in vitro gastrointestinal release of amoxicillin

Superabsorbent polymer composites (SAPCs) are very promising and versatile materials for biomedical applications. This study concentrates on the development of novel cellulose‐based SAPC, Poly(acrylic acid‐co‐acrylamide‐co?2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid)‐grafted nanocellulose/poly(vinyl alcohol) composite, P(AA‐co‐AAm‐co‐AMPS)‐g‐NC/PVA, as a potential drug delivery vehicle. Amoxicillin was selected as a model drug, which is used for the treatment of Helicobacter pylori induced peptic and duodenal ulcers. P(AA‐co‐AAm‐co‐AMPS)‐g‐NC/PVA was synthesized by graft copolymerization reaction, and FTIR, XRD, SEM, and DLS analyses were performed for its characterization. Equilibrium swelling studies were conducted to evaluate the stimuli‐response behavior of the SAPC and found that equilibrium swelling was dependent on pH, contact time, temperature, ionic strength, concentration of crosslinker and PVA. Maximum drug encapsulation efficiency was found out by using different concentrations of amoxicillin. Drug release studies were carried out at simulated gastric and intestinal fluids and the release % was observed as maximum in intestinal fluids within 4 h. The drug release kinetics was investigated using Peppas' potential equation and follows non‐Fickian mechanism at pH 7.4. Thus, the drug release experiments indicate that P(AA‐co‐AAm‐co‐AMPS)‐g‐NC/PVA would be a fascinating vehicle for the in vitro administration of amoxicillin into the gastrointestinal tract. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40699.     

Properties of high‐temperature‐resistant drilling fluids incorporating acrylamide/(acrylic acid)/(2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid) terpolymer and aluminum citrate as filtration control agents

A terpolymer of acrylamide (AM), acrylic acid (AA), and 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) was synthesized by a free‐radical solution polymerization technique, characterized by FTIR methods, and applied together with aluminum citrate in oilfield drilling as a high‐temperature‐resistant filtration control agent. Before and after thermal aging for 16 h at 180°C, the combined effect of the terpolymer and aluminum citrate on the Bingham‐type rheological and fluid‐loss properties of the corresponding fresh‐water and salt‐water muds was further investigated. The results showed that before the thermal aging, there was a similar changing trend in the rheological and fluid‐loss properties of the muds with terpolymer concentration, regardless of the presence of aluminum citrate. After the thermal aging, some hydrophilic polycomplexes of AM‐AA‐AMPS terpolymer with aluminum citrate may have been formed and consequently inhibited viscosity loss of the muds, thereby improving the fluid‐loss properties. A possible mechanism is proposed to explain the improvement. J. VINYL ADDIT. TECHNOL, 2010. © 2009 Society of Plastics Engineers     

Study on the morphology of the hydrophobically‐modified polyelectrolyte in aqueous solution by AFM measurements

This work focuses on the AFM study of the aggregation morphology and association mechanism of the hydrophobically‐association water‐soluble polymer P (AM‐AA‐BPAM) in aqueous solution. It shows that the P (AM‐AA‐BPAM) molecule chain, which has hydrophobic and hydrophilic ionic groups, forms the “spherical” aggregations as micelles below 0.2 g · dL^?1, and then connect each other to form the string‐like aggregations, which produce large viscosity for the polymer solution. It is also coincident with the FCS, DLS, and viscosity study result. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1175–1178, 2004     

丙烯酸-丙烯酰胺共聚物吸水树脂的制备

采用溶液聚合法,以丙烯酸(AA)和丙烯酰胺(AM)为单体,N,N’-亚甲双丙烯酰胺(NMBA)为交联剂,过硫酸铵为引发剂,制备了丙烯酸-丙烯酰胺共聚物吸水树脂,探讨了单体配比(mAA/mAM)、交联剂和引发剂用量对树脂吸水率的影响。结果表明:在65℃时,丙烯酸-丙烯酰胺共聚物吸水树脂的最佳制备条件为:丙烯酸和丙烯酰胺质量比为4:1,交联剂和引发剂用量分别为聚合单体(丙烯酸和丙烯酰胺)总质量的0.02%和0.4%。     

Synthesis and solution properties of temperature‐sensitive copolymers based on NIPAM

A kind of temperature‐sensitive water‐soluble polymers P(NIPAM‐HEMA‐AM) of N‐isopropylacrylamide (NIPAM), hydroxyethyl methacrylate (HEMA) and acrylamide (AM) were synthesized by free radical aqueous solution copolymerization. The polymers were characterized by Fourier transform infrared spectrum (FTIR) method. Solution properties, such as the influences of monomer ratios and additives on the low critical soluble temperature (LCST) of the polymer solutions as well as the viscosity‐temperature properties were studied. The results show that the polymer concentrations have no significant influence on the LCST of polymer solutions. The incorporation of HEMA units leads to a lower LCST, while AM units to a higher LCST. The additions of small molecules such as salt and surfactant also have significant effect on the LCST, the addition of NaCl decreases the LCST, while the addition of sodium dodecylbenzenesulfonate (SDBS) increases the LCST. The apparent viscosity of polymer solutions depends on temperature. The 1.5 wt % aqueous solutions of P(NIPAM‐HEMA‐AM) exhibits good thermo‐thickening behavior over 55°C, whereas the 0.8 wt % aqueous solutions do not show this behavior during the heating process. The aqueous solutions of P(NIPAM‐HEMA‐AM) are viscoelastic fluids, and the viscoelasticities mainly depend on temperature. Both the storage modulus (G') and loss modulus (G'') of 1.5 wt % polymer solutions increase with temperature. Over 55°C, G' exceeds G'', and the polymer solutions are elasticity‐dominated. In contrast, below 55°C, G'' is larger than G', and the polymer solutions are viscosity‐dominated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010