Upper or lower critical solution temperature, or both? Studies on cationic copolymers of N-isopropylacrylamide

Karjalainen, Erno; Aseyev, Vladimir; Tenhu, Heikki

doi:10.1039/c4py01700e

Cited by 25 publications

(46 citation statements)

References 59 publications

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“…Copolymer gels were prepared of a mixture of AMPTMA and NIPAM. The motivation for the addition of cationic repeating units to the polymer was based on a recent finding that a hydrophobic anion NTF 2 binds to the cations and decreases the solubility of the polymer to such an extent that UCST behavior may be observed …”

Section: Discussionmentioning

confidence: 99%

“…The motivation for the addition of cationic repeating units to the polymer was based on a recent finding that a hydrophobic anion NTF 2 binds to the cations and decreases the solubility of the polymer to such an extent that UCST behavior may be observed. 27 By incorporating synthetic laponite XLS to the hydrogel, the rheological properties and stiffness of the hybrid hydrogels were improved. However, the combination of a cationic monomer and a bulky hydrophobic counterion led to much stronger gels.…”

Section: Discussionmentioning

confidence: 99%

“…The first observation is that the introduction of AMPTMA in the polymerization suppresses the phase transition of PNIPAM in distilled water (sample S4), as has earlier been observed for solutions of linear PNIPAM-AMPTMA copolymers. 27 But in the sample S4 swollen in 5 mM salt solution of LiNTf 2 , we can observe volume phase transition temperature, around 398C upon heating (taken as the peak temperature of the endotherm). The same behavior is observed in the swelling studies.…”

Section: Differential Scanning Calorimetrymentioning

confidence: 94%

“…12,19,[24][25][26] The stress-strain behavior and tensile strength of photopolymerized nanocomposite PNIPAM hydrogels with changing photoinitiator concentration have been reported by Haraguchi. 12 However, rheological properties of photopolymerized cationic nanocomposite copolymer gels of Nisopropylacrylamide 27 have not been investigated.…”

Section: Introductionmentioning

confidence: 99%

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Rheological properties of thermoresponsive nanocomposite hydrogels

Hosseini

Tenhu

Hietala

2015

J of Applied Polymer Sci

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Highly elastic and robust nanocomposite hydrogels based on N-isopropylacrylamide (NIPAM) and cationic (3-acrylamidopropyl) trimethylammonium chloride (AMPTMA) were synthesized by photopolymerization. Nanoscopic clay, laponite XLS, was added in the gels during the synthesis. The effect of a hydrophobic salt, lithium bis(trifluoromethane) sulfonimide (LiNTf 2 ), and clay content on the viscoelastic properties, swelling ratio, and stiffness of the nanocomposite hydrogels were investigated as a function of temperature. Synthetic clay served as a multifunctional cross-linker, producing hydrogels with enhanced elastic properties. Anionic NTf 2 binds to the cationic comonomer units and significantly affected the viscoelasticity and thermal properties. DSC measurements showed that the volume phase transition temperature and its enthalpy changed with the clay content and with introducing the cationic comonomer (AMPTMA) in the PNIPAM network. With the addition of either laponite XLS or the comonomer and 5 mM solution of LiNTf 2 , a fourfold and fivefold increase in elastic modulus was obtained, respectively, compared to that of the homopolymer PNIPAM hydrogel. With increasing the temperature from 20 to 458C for the copolymer gel with 10% AMPTMA in 5 mM LiNTf 2 , the elastic modulus grew 15 times larger.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Differential Scanning Calorimetrymentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Rheological properties of thermoresponsive nanocomposite hydrogels

Hosseini

Tenhu

Hietala

2015

J of Applied Polymer Sci

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“…Recently, copolymerization of a H‐bonding monomer with a comonomer that does not form H‐bonds itself has become a very versatile approach to the design of new UCST‐type copolymers . Interestingly, copolymerization of a cationic monomer with N ‐isopropylacrylamide provided both UCST and LCST . Some well‐known early examples of UCST‐type polymers based on electrostatic interaction are zwitterionic polymers .…”

Section: Introductionmentioning

confidence: 99%

RAFT Synthesis in Water of Cationic Polyelectrolytes with Tunable UCST

Cao

2015

Macromol. Rapid Commun.

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Cationic polyelectrolytes showing an upper critical solution temperature (UCST) are synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization in water at a temperature well above the UCST. The polymerization is well controlled by the RAFT process, with excellent pseudo-first-order kinetics. The cloud point is highly dependent on the polyelectrolyte concentration, molecular weight, and presence of added electrolyte. Alkylation of a neutral polymer is also conducted to obtain polyelectrolytes with different hydrophobic groups, which are shown to increase the cloud point.

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Biointerfacial Analysis of HEK293 Cells in Contact with Hydrogels based on Poly‐N‐Isopropylacrylamide and Copolymers

Capella

Liaudat

Broglia

et al. 2022

Adv Materials Inter

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Several researches have demonstrated that synthetic hydrogels can mimic the mechanical and physicochemical properties of native extracellular matrices and act as cell‐scaffold. The biointerface can influence over tissue activities such as adhesion, signaling, cell–cell communications, and proliferation. In this work, the behavior of human embryonic kidney cells (HEK293) in contact with hydrogel surfaces based on poly‐N‐isopropylacrylamide (PNIPAM) and copolymers is studied. Ionic and neutral hydrogel surfaces are synthesized by free radical polymerization and characterized by Fourier‐transform infrared spectroscopy, swelling capacity, and wettability at culture conditions. Viability, proliferation, and bioadhesive capacity are analyzed by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide and Neutral Red assays, [3H]‐thymidine technique, Acridine Orange and Hoechst dye. Noncytotoxic and proliferative effects are observed in all cases. HEK293 cells are mainly adapted and adhered on neutral and low ionic charge surfaces showing typical cell morphology, and normal mitotic rates. While, lower adhesion, abnormal nuclear and cytoplasmic morphologies with mitotic/fragmentation processes are observed after contact with high ionic surfaces. The cellular cycle after cultive on PNIPAM, assessed by flow cytometry, is not affected regarding control surfaces (polystyrene). Therefore, hydrogel surfaces with neutral and low ionic charges can be apt to in vitro tissue development and possible applications of biomedical treatments.

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Upper or lower critical solution temperature, or both? Studies on cationic copolymers of N-isopropylacrylamide

Abstract: The solution properties of statistical copolymers of N-isopropyl acrylamide (NIPAm) and cationic (3-acrylamidopropyl) trimethylammonium chloride (AMPTMA) have been studied.

Cited by 25 publications

References 59 publications

Rheological properties of thermoresponsive nanocomposite hydrogels

Rheological properties of thermoresponsive nanocomposite hydrogels

RAFT Synthesis in Water of Cationic Polyelectrolytes with Tunable UCST

Biointerfacial Analysis of HEK293 Cells in Contact with Hydrogels based on Poly‐N‐Isopropylacrylamide and Copolymers

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