Fast pH‐thermo‐responsive copolymer hydrogels with micro‐porous structures

Micro‐porous copolymer hydrogels were prepared by γ‐ray irradiation of mixed solutions of N‐isopropylacrylamide (NIPAAm) and acrylic acid (AAc) above the lower critical solution temperature (LCST). From Cryo‐SEM observations, the gels were found to consist of three‐dimensional fibrous micro‐gels and micro‐pores. The copolymer gels swelled at temperatures below the LCST and shrunk at temperatures above it, and they showed rapid volume transitions on a time scale on the order of a minute when experiencing temperature changes between 10 and 40°C. The transition times for thermal shrinking were almost the same regardless of AAc composition, but the transition times for thermal swelling were increased with increasing AAc contents. The copolymer gels also showed rapid volume transitions with time constants on the order of an hour on experiencing pH changes between 2 and 12. The transition times for pH volume change at 10°C were within one hour, except for the gels containing only small amounts of AAc. On the other hand, the transition times for pH‐dependent volume change at 40°C were increased with increasing AAc content. The lower responsiveness of the transition results from an increase in hydrophobicity arising from the formation of inter‐ and intra‐molecular hydrogen bonds between the non‐ionized carboxylic acid groups and the amide groups. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 75–84, 2003     

Copolymers of N‐isopropylacrylamide,HEMA‐lactate and acrylic acid with time‐dependent lower critical solution temperature as a bioresorbable carrier

Copolymers of N‐isopropylacrylamide (NIPAAm), 2‐hydroxyethyl methacryl lactate (HEMA‐lactate) and acrylic acid (AAc) were prepared, with varying mole ratios of monomers, to develop a bioresorbable in‐situ‐gelling material with a time‐dependent lower critical solution temperature (LCST). The synthesized copolymers were characterized by nuclear magnetic resonance, gel permeation chromatography and differential scanning calorimetry. In 0.1 M phosphate‐buffered saline solution of pH 7.4, these copolymers had an LCST below body temperature. The LCST decreased as the HEMA‐lactate content of the copolymers was increased. Furthermore, in these conditions, the LCST of the copolymers exhibited time‐dependent properties, due to hydrolysis of the HEMA‐lactate. As the HEMA‐lactate hydrolyzed, the copolymers became more hydrophilic, thereby leading to an increase in LCST. This hydrophilicity caused copolymers of approximately 6 mol% of AAc to exhibit an LCST above body temperature after hydrolysis. In neutral solution, copolymers with varying mol% of AAc saw their LCST rise above 37 °C within one to ten days, depending upon the HEMA‐lactate/NIPAAm ratio, due to the complete hydrolysis of the HEMA‐lactate. The above properties indicate that these copolymers would be useful for drug delivery because their variable LCST makes them bioresorbable. Copyright © 2004 Society of Chemical Industry     

Independent control of lower critical solution temperature and swelling behavior with pH for poly(N‐isopropylacrylamide‐co‐maleic acid)

Polymer solutions that gel in response to changes in temperature and pH are of interest for various forms of drug delivery, and it is desirable to increase swelling for diffusion‐controlled release without bringing the lower critical solution temperature (LCST) above 37°C. N‐isopropylacrylamide (NIP) was polymerized with maleic acid (MAc), a diprotic acid, and acrylic acid (AAc), a monoprotic acid, to compare swelling and temperature response with changes in pH. For samples with equal acid contents and almost identical LCST responses to pH, poly(N‐isopropylacrylamide‐co‐maleic acid) (pNIP MAc) demonstrated greater swelling than poly(N‐isopropylacrylamide‐co‐acrylic acid) (pNIP AAc). The LCST increase for MAc occurred at a pH corresponding to the deprotonation of almost all of the first acid groups. Further increases in pH led to the deprotonation of the second ? COOH and only served to increase the charge concentration at a given location. These results provide strong support for the theory that LCST results largely from uninterrupted chain lengths of NIP and that swelling results from the actual charge density of acid groups along the chain. Because the use of a diprotic acid copolymer allows swelling to be decoupled from LCST, pNIP MAc may be an appropriate candidate for pH‐sensitive drug‐delivery applications. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2110–2116, 2004     

Thermo‐ and pH‐ responsive copolymers: Poly(n‐Isopropylacrylamide‐co‐IAM) copolymers

Poly(N‐isopropylacrylamide) (NIPAAm) is well known as a smart material with good thermal sensitivity and favorable biocompatibility. A series of new smart hydrogels, NIPAAm copolymerized with IAM (itaconamic acid; 4‐amino‐2‐methylene‐4‐oxobutanoic acid), were synthesized through radical solution polymerization in this work. Poly(NIPAAm‐co‐IAM) can respond to the changes of temperature as well as pH value. Such a characteristic is due to the fact that IAM contains not only a hydrophilic acrylic acid moiety but also an acrylamide moiety to be thermal and pH sensitive. The experimental results show that the lower critical solution temperature (LCST) of the copolymer increases as the molar fraction of IAM increases. Moreover, based on the current experimental data, 3 wt % of Poly(NIPAAm‐co‐IAM) aqueous solution in this study exhibits a phase transition temperature (37.8°C) close to the human body temperature in the buffer solution of pH 7 possibly to be useful in drug delivery. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42367.     

Environmentally sensitive hydrogels: N‐isopropyl acrylamide/Acrylamide/ Mono‐, Di‐, Tricarboxylic acid crosslinked polymers

Environmentally sensitive hydrogels responsive to various stimuli such as temperature, pH, ionic strength of the medium and the solvent were prepared by using N‐isopropyl acrylamide (NIPAM), acrylamide (AAm) and monomers that have various number of carboxylic acid (XA) functionality using N,N′‐methylene bisacrylamide (Bis) as crosslinker. Hydrogels were prepared via free radical polymerization reaction in aqueous solution. P(NIPAAm‐co‐AAm) and p(NIPAAm‐co‐AAm)/XA hydrogels that contain monoprotic crotonic acid (CA) exhibit a lover critical solution temperature (LCST) at 28°C, whereas p(NIPAAm‐co‐AAm)/IA (IA:itaconic acid), and P(NIPAAm‐co‐AAm)/ACA (ACA:acotonic acid) hydrogels exhibit a lover critical solution temperature at 30.7°C and 34.4°C, respectively. Spectroscopic and thermal analyses were performed for the structural and thermal characterizations of the prepared hydrogel. The swelling experiments as equilibrium swelling percentages by gravimetrically were carried out in different solvents, at different solutions temperature, pH, and ionic strengths to determine their effects on swelling characteristic of hydrogels. POLYM. ENG. SCI., 55:843–851, 2015. © 2014 Society of Plastics Engineers     

Radiation synthesis and characterization of poly(N‐vinyl‐2‐pyrrolidone/acrylic acid) and poly(N‐vinyl‐2‐pyrrolidone/acrylamide) hydrogels for some metal‐ion separation

Two different hydrogels, prepared from N‐vinyl‐2‐pyrrolidone/acrylic acid (NVP/AAc) and N‐vinyl‐2‐pyrrolidone/acrylamide (NVP/AAm), were studied for the separation and extraction of some heavy‐metal ions from wastewater. The hydrogels were prepared by the γ‐radiation‐induced copolymerization of the aforementioned binary monomer mixtures. Further modification was carried out for the NVP/AAc copolymer through an alkaline treatment to improve the swelling behavior by the conversion of the carboxylic acid groups into its sodium salts. The thermal stability and swelling properties were also investigated as functions of the N‐vinyl‐2‐pyrrolidone content. The characterization and some selected properties of the prepared hydrogels were studied, and the possibility of their practical use in wastewater treatment for heavy metals such as Cu, Ni, Co, and Cr was investigated. The maximum uptake for a given metal was higher for a treated NVP/AAc hydrogel than for an untreated NVP/AAc hydrogel and was higher for an untreated NVP/AAc hydrogel than for an NVP/AAm hydrogel. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2642–2652, 2004     

Formation of thermosensitive water‐soluble copolymers with phosphinic acid groups and the thermosensitivity of the copolymers and copolymer/metal complexes

Thermosensitive and water‐soluble copolymers were prepared through the copolymerization of acryloyloxypropyl phosphinic acid (APPA) and N‐isopropyl acrylamide (NIPAAm). The thermosensitivity of the copolymers and copolymer/metal complexes was studied. The APPA–NIPAAm copolymers with less than 11 mol % APPA moiety had a lower critical solution temperature (LCST) of approximately 45°C, but the APPA–NIPAAm copolymers with greater than 21 mol % APPA moiety had no LCST from 25 to 55°C. The APPA–NIPAAm copolymers had a higher adsorption capacity for Sm³⁺, Nd³⁺, and La³⁺ than for Cu²⁺, Ni²⁺ and Co²⁺. The APPA–NIPAAm (10:90) copolymer/metal (Sm³⁺, Nd³⁺, or La³⁺) complexes became water‐insoluble above 45°C at pH 6–7, but the APPA–NIPAAm (10:90) copolymer/metal (Cu²⁺,Ni²⁺, or Co²⁺) complexes were water‐soluble from 25 to 55°C at pH 6–7. The temperature at which both the APPA–NIPAAm copolymers and the copolymer/metal complexes became water‐insoluble increased as the pH values of the solutions increased. The APPA–NIPAAm copolymers were able to separate metal ions from their mixed solutions when the temperature of the solutions was changed; this was followed by centrifugation of the copolymer/metal complexes after the copolymers were added to the metal solutions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 116–125, 2004     

Synthesis of water‐soluble thermosensitive polymers having phosphonium groups from methacryloyloxyethyl trialkyl phosphonium chlorides–N‐isopropylacrylamide copolymers and their functions

Water‐soluble thermosensitive polymers having phosphonium groups were synthesized by the copolymerization of N‐isopropylacrylamide (NIPAAm) with methacryloyloxyethyl trialkyl phosphonium chlorides (METRs) having varying alkyl lengths. The relative viscosities of the copolymer solutions increased with increasing content of phosphonium groups in the copolymers and decreased with increasing chain length of alkyl chains in the phosphonium groups. However, the copolymers of METR with octyl groups in phosphonium groups (METO) and NIPAAm became water insoluble with increasing contents of METO moieties in the copolymers. The transmittance at 660 nm of the copolymer solutions above the lower critical solution temperature (LCST) decreased gradually with increasing temperature and decreased with increasing chain length of alkyl chains in the phosphonium groups. The transmittance at 660 nm of the copolymer solutions above the LCST was greatly affected by the addition of neutral salts such as KCl. The copolymers of METR with ethyl groups in phosphonium groups and NIPAAm and those of METR with butyl groups in phosphonium groups and NIPAAm had high flocculating abilities against bacterial suspensions. The METO–NIPAAm copolymer was found to have a high antibacterial activity. The flocculating ability and the antibacterial activity of the copolymers were affected by not only the content of phosphonium groups but also the alkyl chain length in the phosphonium groups in the copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 386–393, 2003     

Synthesis and characterization of pH‐sensitive crosslinked (NIPA‐co‐AAC) nanohydrogels copolymer

A thermoresponsive polymeric nanohydrogels has been synthesized by inverse microemulsion polymerization of N‐isopropylacrylamide (NIPA) and acrylic acid (AAc) using Aerosol (AOT) as a surfactant, ethylene glycol dimethacrylate (EGDMA) as a crosslinker, and 2,2′‐azobisisobutyronitrile (AIBN) as initiator. The effect of concentration of AIBN, EGDMA, and NIPA/AAc weight ratio was investigated. The lower critical solution temperature (LCST) of poly (NIPA‐co‐AAC) can be manipulated to be 40°C and 45°C which was correlated to amount of AAc that was copolymerized with NIPA. FTIR, 1H NMR, TEM, and DSC characterized the nanohydrogels. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A study on solution properties of poly(N,N‐diethylacrylamide‐co‐acrylic acid)

Poly(N,N‐diethylacrylamide) (PDEA), poly(acrylic acid) (PAA), and a series of (N,N‐diethylacrylamide‐co‐acrylic acid) (DEA‐AA) random copolymers were synthesized by the method of radical polymerization. The measurement of turbidity showed that the phase behaviors of the brine solutions of the copolymers changed dramatically with the mole fraction of DEA (x) in these copolymers. Copolymers cop6 (x = 0.06) and cop11 (x = 0.11) in which acrylic acid content was higher presented the upper critical solution temperature (UCST) phase behaviors similar to PAA. Copolymer cop27 (x = 0.27) presented the lower critical solution temperature (LCST) behavior similar to PDEA. While copolymer cop18 (x = 0.18) in which acrylic acid content was moderate presented both UCST and LCST behaviors. The solution properties of the polymers were investigated by measurements of viscosity, fluorescence, and pH. It is reasonable to suggest that the sharp change of the phase behavior may be attributed to the interaction between acrylamide group and carboxylic group in the (DEA‐AA) copolymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Stimuli‐responsive properties of aminophenylboronic acid‐carrying thermosensitive copolymers

Thermosensitive copolymers of N‐isopropylacrylamide (NIPA) and N‐acryloxysuccinimide (NASI) were obtained by solution polymerization using azobisisobutyronitrile as the initiator in a tetrahydrofuran–toluene mixture at 65 °C. A boronic acid‐carrying ligand, m‐aminophenylboronic acid (APBA) was covalently attached to the thermosensitive copolymer via the reaction between amino and succinimide groups. APBA‐coupled thermosensitive copolymer exhibited both temperature and pH sensitivity. Thermally reversible phase transitions were observed both in the acidic and alkaline pH region for the APBA‐modified copolymers obtained with different NASI feed concentrations. In our study, ribonucleic acid (RNA) was selected as a biomolecule having reactive groups which could potentially interact with the boronic acid functionality. The response of boronic acid‐carrying thermosensitive copolymer against RNA was investigated in aqueous media in the pH range 4–9. In the acidic pH region, an increase was observed in the lower critical solution temperature (LCST) of the APBA‐coupled thermosensitive copolymer with increasing RNA concentration. However, LCST decreased with increasing RNA concentration at both neutral and alkaline pH values. The LCST of the APBA‐attached copolymer varied linearly with the RNA concentration at pH of 3, 4 and 7. © 2003 Society of Chemical Industry     

Thermo‐responsive injectable hydrogel system based on poly(N‐isopropylacrylamide‐co‐vinylphosphonic acid). I. Biomineralization and protein delivery

To achieve the injectable hydrogel system in order to improve bone regeneration by locally delivering a protein drug including bone morphogenetic proteins, thermo‐responsive injectable hydrogels composed of N‐isopropylacrylamide (NIPAAm) and vinyl phosphonic acid (VPAc) were prepared. The P(NIPAAm‐co‐VPAc) hydrogels were also biomineralized by urea‐mediation method to create functional polymer hydrogels that deliver the protein drug and mimic the bone extracellular matrix. The loosely cross‐linked P(NIPAAm‐co‐VPAc) hydrogels were pliable and fluid‐like at room temperature and could be injected through a small‐diameter aperture. The lower critical solution temperature (LCST) of P(NIPAAm‐co‐VPAc) hydrogel was influenced by the monomer ratio of NIPAAm/VPAc and the hydrogel with a 96/4 molar ratio of NIPAAm/VPAc exhibited an LCST of ～34.5°C. Water content was influenced by temperature, NIPAAm/VPAc monomer ratio, and biomineralization; however, all hydrogels maintained more than about 77% of the water content even at 37°C. In a cytotoxicity study, the P(NIPAAm‐co‐VPAc) and biomineralized P(NIPAAm‐co‐VPAc) hydrogels did not significantly affect cell viability. The loading content of bovine serum albumin in hydrogel, which was used as a model drug, gradually increased with the amount of VPAc in the hydrogel owing to the ionic interaction between VPAc groups and BSA molecules. In addition, the release behavior of BSA from the P(NIPAAm‐co‐VPAc) hydrogels was mainly influenced by the drug loading content, water content, and biomineralization of the hydrogels. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

A novel route for synthesis of temperature responsive nanoparticles

We report the preparation of responsive silica nanoparticles by reaction of epoxy modified silica with stimuli responsive poly (acrylic acid‐N‐isopropylacrylamide) (poly (AA‐co‐NIPAAm)). A series of copolymers of poly (AA‐co‐NIPAAm) were synthesized by a novel route, employing solid state condensation of polyacrylic acid and isopropyl amine in different feed ratios (44 mol %–100 mol % AA). The structure of the copolymers was characterized by FT‐IR, ¹H‐NMR. The lower critical solution temperature (LCST) was found to vary with the copolymer composition. The pH dependence of the LCST was also observed, and the copolymers exhibited a higher LCST at neutral pH than at acidic pH (4–5). Selected copolymers were used to prepare responsive core‐shell particles. Silica nanoparticles modified using glycidoxy propyl trimethoxy propyl silane were reacted with the responsive copolymer to form responsive core‐shell particles. The influence of reaction conditions on the modification of silica particles and reaction with responsive copolymers was investigated. The hydrodynamic behavior of the synthesized thermo responsive nanoparticles was also studied. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Graft copolymer–lanthanide complexes obtained by radiation grafting on polyethylene film

Radiation‐induced grafting of acrylic acid (AAc) onto polyethylene (PE) film was investigated. The grafted films rapidly adsorbed Eu, Gd, Tb, and Dy ions at high efficiency. The carboxylic acid groups on the AAc‐grafted PE film acted as a chelating site for the selected lanthanide ions. Complex formation of lanthanide ions and the carboxylic acid group on PE film was investigated by IR, FT–Raman, and X‐ray photoelectron spectroscopy (XPS). Photoluminescence (PL) spectra and the thermal properties of the graft copolymer–lanthanide complexes onto PE film were also investigated. The application of such prepared graft copolymer–lanthanide complexes in the field of fluorescence emission displays (FEDs) may be interest. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 328–336, 2003     

Thermoreversible hydrogels. VII. Synthesis and swelling behavior of poly(N‐isopropylacrylamide‐co‐3‐methyl‐1‐vinylimidazolium iodide) hydrogels

A series of N‐isopropylacrylamide/3‐methyl‐1‐vinylimidazolium iodide (NIPAAm/MVI) copolymer gels were prepared from the various molar ratios of NIPAAm, cationic monomer MVI, and N,N′‐methylene bisacrylamide (NMBA) in this study. The influence of the amount of MVI in the copolymer gels on the swelling behaviors was investigated in various aqueous saline solutions. Results showed that the swelling ratios (SRs) of copolymer gels were significantly greater than those of NIPAAm homopolymer gels, and the higher the MVI content, the higher the volume phase transition temperature. The SRs for the NIPAAm/MVI copolymer gels decreased with an increase of the salt concentration. In various saline solutions, results showed that the effect of divalent ions on the SR was greater than that of monovalent ions for these hydrogels. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3242–3253, 1999     

N‐(2‐hydroxypropyl)methacrylamide‐based polymer conjugates with pH‐controlled activation of doxorubicin. I. New synthesis,physicochemical characterization and preliminary biological evaluation

New method of synthesis of water‐soluble polymer‐drug conjugates, exhibiting remarkable anticancer activity in mice models, has been developed. In the conjugates, an anticancer drug doxorubicin (DOX) is attached to a polymer carrier based on N‐(2‐hydroxypropyl)methacrylamide (HPMA) copolymer via a hydrolytically labile hydrazone bond. New methacrylamide‐type comonomers, containing either hydrazide group or hydrazon of DOX, were used for copolymerization with HPMA. In contrast to the synthetic procedure described earlier the new method is simpler, cheaper, and results in a better‐defined conjugate structure. The conjugates are fairly stable in buffer at pH 7.4 (model of blood stream) but release DOX under mild acid conditions modeling the tumor microenvironment. The conjugates showed significant in vivo antitumor activity in treatment of T‐cell lymphoma EL‐4 bearing mice with up to 100% long‐term survivors. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Study of dual responsive poly[(maleilated dextran)‐graft‐(N‐isopropylacrylamide)] hydrogel nanoparticles: preparation,characterization and biological evaluation

BACKGROUND: Much interest has recently been shown in fundamental studies and technological developments of polymeric nanoparticles. Novel dual temperature‐ and pH‐sensitive stabilized nanoparticles composed of maleilated dextran (Dex‐MA) and N‐isopropylacrylamide (NIPAAm) were prepared and investigated to be used for the controlled release of 10‐hydroxycamptothecin. RESULTS: The resultant nanoparticles showed spherical geometry, with diameters ranging from 60 to 300 nm, the variation achieved by adjusting the composition ratio or the amounts of surfactant. The size of the nanoparticles increased and the zeta potential reversed with an increase of pH. Also, the lower critical solution temperature (LCST) decreased at pH = 3.0, but increased at pH = 6.0, which suggests that the LCST is dependent on pH. Drug release results obtained showed encapsulation and loading efficiencies were 62.9% and 0.82%, respectively. Cytotoxicity assay of this copolymer indicated no significant toxicity. CONCLUSION: Novel dual temperature‐ and pH‐sensitive Dex‐MA‐graft‐PNIPAAm nanoparticles may provide some advantages for anti‐cancer drug delivery due to a tunable LCST from 35 to 45 °C and controllable dimensions. These nanoscale materials could be excellent candidates for biotechnology and biomedical applications. Copyright © 2009 Society of Chemical Industry     

Synthesis and characterization of radio‐opaque thermosensitive poly[N‐isopropylacrylamide‐2,2′‐(ethylenedioxy)bis(ethylamine)‐2,3,5‐triiodobenzamide]

BACKGROUND: In situ gelling polymers, like poly(N‐isopropylacrylamide) (poly(NIPAAm)), have many potential medical applications due to their biocompatibility and thermosensitivity. RESULTS: Radio‐opaque thermosensitive poly(NIPAAm) grafted with 10.7 wt% 2,2′‐(ethylenedioxy)bis(ethylamine)‐2,3,5‐triiodobenzamide was successfully synthesized and characterized. The conjugated polymer showed good visibility with X‐ray fluoroscopy. The polymer had a lower critical solution temperature of 30 °C after conjugation with triiodobenzamide as determined by cloud point determination and a transition peak temperature of 33.3 ± 0.57 °C as determined by differential scanning calorimetry. CONCLUSION: The polymer synthesized was highly visible under X‐rays, based upon the percentage incorporation of triiodobenzamide. After conjugation of the NIPAAm to the triiodobenzamide through a bis(ethylamine) linkage, the resultant polymer retained lower critical solution temperature characteristics in a temperature region that makes it physiologically useful. Copyright © 2009 Society of Chemical Industry     

Thermoresponsive behaviour in aqueous solution of poly(maleic acid‐alt‐vinyl acetate) grafted with poly(N‐isopropylacrylamide)

The synthesis of a thermoresponsive graft copolymer consisting of a maleic acid/vinyl acetate alternating copolymer backbone (MAc‐alt‐VA) and poly(N‐isopropylacrylamide) (PNIPAM) side chains is reported. Turbidimetric measurements in dilute aqueous solutions showed that no macroscopic phase separation takes place when the temperature is raised above the lower critical solution temperature (LCST) of PNIPAM, even at pH = 2. Moreover, in semi‐dilute aqueous solutions, a pronounced thermally induced viscosity increase (thermothickening) was observed. This thermoresponsive behaviour has been attributed to the interconnection of the hydrophilic MAc‐alt‐VA graft copolymer backbones by means of the hydrophobic PNIPAM side chain aggregates formed as the temperature increases above the LCST of this polymer. Copyright © 2004 Society of Chemical Industry     

Poly(N‐isopropylacrylamide‐co‐poly(ethylene glycol))‐acrylate simultaneously physically and chemically gelling polymer systems

In an effort to create an in situ physically and chemically cross‐linked hydrogel for in vivo applications, N‐isopropylacrylamide (NIPAAm) was copolymerized with poly(ethylene glycol)‐monoacrylate (PEG‐monoacrylate) and then the hydroxyl terminus of the PEG was further modified with acryloyl chloride to form poly(NIPAAm‐co‐PEG) with acrylate terminated pendant groups. In addition to physically gelling with temperature changes, when mixed with a multi‐thiol compound such as pentaerythritol tetrakis 3‐mercaptopropionate (QT) in phosphate buffer saline solution of pH 7.4, this polymer formed a chemical gel via a Michael‐type addition reaction. The chemical gelation time of the polymer was affected by mixing time; swelling of the copolymer solutions was temperature dependant. Because of its unique gelation properties, this material may be better suited for long‐term functional replacement applications than other thermo‐sensitive physical gels. Also, the PEG content of this material may render it more biocompatible than similar HEMA‐based precursors in previous simultaneous chemically and physically gelling materials. With its improved mechanical strength and biocompatibility, this material could potentially be applied as a thermally gelling injectable biomaterial for aneurysm or arteriovenous malformation (AVM) occlusion. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007