Poly(N-isopropylacrylamide) hydrogels with improved shrinking kinetics by RAFT polymerization

Liu, Qunfeng; Zhang, Ping; Qing, Aixiang; Lan, Ya‐Qian; Lu, Mangeng

doi:10.1016/j.polymer.2006.02.006

Cited by 110 publications

(89 citation statements)

References 43 publications

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“…Numerous methods have been employed to this end, e.g. the addition of inorganic particles [24][25][26], of micro- [27] or nanospheres [28] made of organic polymers, the use of microgel additives [29], polymerization in the presence of a sucrose solution which undergoes phase separation in the later reaction stages [30], polymerization of the NIPAm monomer at T > LCST [31] (in-situ product precipitation to porous structures), introduction of side chains on the elastic PNIPAm backbone (comb-grafted structures) [32][33][34][35] [polymerization in vacuum at room temperature (water vapor bubbles as porogen) [36], or freeze-drying and hydration treatment of bulk gels [37,38]. A very attractive method is the so-called cryogel synthesis (cryostructuration), the in-situ sw formation of solvent crystals as pore templates, which are removed by melting after the NIPAm polymerization, as described by Kirsebom and Mattiasson [39], Zhang and Zhuo [40] and Lozinsky [41,42].…”

Section: Introductionmentioning

confidence: 99%

Super-porous nanocomposite PNIPAm hydrogels reinforced with titania nanoparticles, displaying a very fast temperature response as well as pH-sensitivity

Huerta-Ángeles

Hishchak

Strachota

et al. 2014

European Polymer Journal

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Section: Introductionmentioning

confidence: 99%

Super-porous nanocomposite PNIPAm hydrogels reinforced with titania nanoparticles, displaying a very fast temperature response as well as pH-sensitivity

Huerta-Ángeles

Hishchak

Strachota

et al. 2014

European Polymer Journal

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“…Zhu and co-workers [20] found both in experiments using oligo(ethylene glycol) dimethacrylates and in corresponding simulations [21] that networks, which were generated via the RAFT process, exhibit an increased homogeneity. Interestingly, Liu et al [22] report an example to the contrary: Comparing pNIPAm gels prepared by RAFT polymerization with conventional gels of similar composition, they found an increased swelling ratio and an increased rate by which the gel shrank upon heating. Such a behavior is typically attributed to increased heterogeneity.…”

Section: Introductionmentioning

confidence: 99%

Electrochemically Induced RAFT Polymerization of Thermoresponsive Hydrogel Films: Impact on Film Thickness and Surface Morphology

Bünsow¹,

Mänz²,

Vana³

et al. 2010

Macro Chemistry & Physics

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Thin hydrogel films of the thermoresponsive polymer poly(N‐isopropylacrylamide) (pNIPAm) were prepared by electrochemically triggered reversible addition‐fragmentation chain transfer (RAFT) polymerization. Two different RAFT agents were employed, which work in either acidic or basic solution. In both cases, addition of RAFT agents had an influence on the thickness and the surface morphology of the films. At low concentration, the polymerization efficiency increased. At high concentration, the efficiency decreased at acidic pH, while it remained constant under basic conditions. Neither RAFT agent displayed electrochemical activity on its own, but they did modify the electrochemical behavior of the initiator. The addition of RAFT agent strongly enhances the homogeneity of the hydrogel surfaces, which presumably is due to a reduced amount of microgel formation.

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“…An increased degree of methacrylate substitution of the CS will increase the crosslink density of the polymer network, causing increased solution viscosity below the LCST and reducing gel swelling capability. Others have investigated different approaches in synthesizing PNIPAAm hydrogels such as atom transfer radical polymerization (ATRP) 35 or reverse addition-fragmentation chain transfer (RAFT) 36 . Polymerization via ATRP has led to the development of narrow, polydisperse hydrogels with fined tuned molecular weight by altering the monomer to initiator ratio.…”

Section: Discussionmentioning

confidence: 99%

Synthesis of Thermogelling Poly(N-isopropylacrylamide)-graft-chondroitin Sulfate Composites with Alginate Microparticles for Tissue Engineering

Christiani

Toomer

Sheehan

et al. 2016

JoVE

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Injectable biomaterials are defined as implantable materials that can be introduced into the body as a liquid and solidify in situ. Such materials offer the clinical advantages of being implanted minimally invasively and easily forming space-filling solids in irregularly shaped defects. Injectable biomaterials have been widely investigated as scaffolds for tissue engineering. However, for the repair of certain load-bearing areas in the body, such as the intervertebral disc, scaffolds should possess adhesive properties. This will minimize the risk of dislocation during motion and ensure intimate contact with the surrounding tissue, providing adequate transmission of forces. Here, we describe the preparation and characterization of a scaffold composed of thermally sensitive poly(N-isopropylacrylamide)-graft-chondroitin sulfate (PNIPAAMg-CS) and alginate microparticles. The PNIPAAm-g-CS copolymer forms a viscous solution in water at RT, into which alginate particles are suspended to enhance adhesion. Above the lower critical solution temperature (LCST), around 30 °C, the copolymer forms a solid gel around the microparticles. We have adapted standard biomaterials characterization procedures to take into account the reversible phase transition of PNIPAAm-g-CS. Results indicate that the incorporation of 50 or 75 mg/ml alginate particles into 5% (w/v) PNIPAAm-g-CS solutions quadruple the adhesive tensile strength of PNIPAAm-gCS alone (p<0.05). The incorporation of alginate microparticles also significantly increases swelling capacity of PNIPAAm-g-CS (p<0.05), helping to maintain a space-filling gel within tissue defects. Finally, results of the in vitro toxicology assay kit, 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) and Live/Dead viability assay indicate that the adhesive is capable of supporting the survival and proliferation of encapsulated Human Embryonic Kidney (HEK) 293 cells over 5 days. Video LinkThe video component of this article can be found at

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Poly(N-isopropylacrylamide) hydrogels with improved shrinking kinetics by RAFT polymerization

Cited by 110 publications

References 43 publications

Super-porous nanocomposite PNIPAm hydrogels reinforced with titania nanoparticles, displaying a very fast temperature response as well as pH-sensitivity

Super-porous nanocomposite PNIPAm hydrogels reinforced with titania nanoparticles, displaying a very fast temperature response as well as pH-sensitivity

Electrochemically Induced RAFT Polymerization of Thermoresponsive Hydrogel Films: Impact on Film Thickness and Surface Morphology

Synthesis of Thermogelling Poly(N-isopropylacrylamide)-graft-chondroitin Sulfate Composites with Alginate Microparticles for Tissue Engineering

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