Investigation of the effect of type and concentration of ionizable comonomer on the collapse behavior ofN-isopropylacrylamide copolymer gels in water

Erbi̇l, Candan; Aras, Seval; Uyanık, Nurseli

doi:10.1002/(sici)1099-0518(19990615)37:12<1847::aid-pola14>3.0.co;2-g

Cited by 37 publications

(2 citation statements)

References 29 publications

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“…Further insights into gel swelling can be gained by considering the Flory–Huggins interaction parameter (χ). Previously, it was reported that χ for PNIPAm/water varies from 0.5 to 0.65 , and that for PNIPAm/methanol, χ is ∼0.45–0.46. , The value of χ for the poly(NIPAm- co - y % MABP)/methanol system was determined experimentally by measuring the second virial coefficient ( A 2 ) from static light scattering measurements. The experimentally derived values range between 0.46 and 0.47, revealing that methanol is a good solvent for poly(NIPAm- co - y % MABP) at all MABP mole fractions (see Figure c,d), and therefore the gels swell more in methanol than in water (χ PNIPAm/water = 0.56–0.99).…”

Section: Results and Discussionmentioning

confidence: 99%

“…The swollen gels were removed from the solvent and blotted with a P5 filter paper to remove the excess solvent and immediately weighed with an accuracy of 0.1 mg until the weight variation was <0.5%. Equation describes an estimation of the swelling ratio for bulk gels. , Similarly, SE was used to measure the swelling of surface-anchored hydrogel films in solvent vapor. For water, the sample was placed in a completely sealed chamber, where the relative humidity (RH) of air was controlled using saturated salt solutions of KOH (RH < 50%) and K 2 S0 4 (RH > 50%).…”

Section: Methodsmentioning

confidence: 99%

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Effect of Network Density in Surface-Anchored Poly(N-isopropylacrylamide) Hydrogels on Adsorption of Fibrinogen

Pandiyarajan

Genzer

2017

Langmuir

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We describe a simple approach to generate surface-attached biocompatible hydrogels with tunable cross-link density and employ them to study the effect of gel structure on protein adsorption. Using free-radical polymerization, we synthesize a series of random copolymers comprising N-isopropylacrylamide (NIPAm) and the photoactive curing agent 4-methacryloyl-oxy-benzophenone (MABP) of mole fractions ranging from 2.5 to 10%. We deposit a thin film of the precursor copolymer (∼150 nm) on a silicon or glass substrate, which is precoated with monolayers of benzophenone-silane, then cross-link it through UV irradiation at 365 nm (dose ≈ 6-10 J/cm) to generate surface-attached networks. A systematic investigation of the network properties such as gel fraction, cross-link density, and swelling ratio reveals that gels with higher MABP content (≥5%) produce densely cross-linked hydrophobic networks with low or no swelling in an aqueous medium. We study the adsorption of fibrinogen (Fg) on such hydrogel substrates and establish that the amount of adsorbed Fg depends on the degree of cross-linking and the swelling capacity of the networks. Specifically, although Fg adsorbs heavily on denser networks, loosely bound gels that swell in aqueous medium repel proteins. We attribute the latter behavior to entropic shielding and size-exclusion factors.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Effect of Network Density in Surface-Anchored Poly(N-isopropylacrylamide) Hydrogels on Adsorption of Fibrinogen

Pandiyarajan

Genzer

2017

Langmuir

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Effects of synthesis-solvent composition and initiator concentration on the swelling behaviour of poly(N-isopropylacrylamide) P(NIPAAM), poly(NIPAAM-co-dimethyl itaconate), and poly(NIPAAM-co itaconic acid) gels

Erbi̇l

Yildiz²,

Uyanık

2000

Polym. Int.

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The effects of synthesis‐solvent composition, initiator concentration, comonomer type and monomer purity on the volume swelling ratios, and polymer‐solvent interaction parameter χ have been investigated as a function of temperature. Non‐ionic N‐isopropylacrylamide (NIPAAM) homopolymer gels, poly[NIPAAM‐co‐(dimethyl itaconate)] (P(NIPAAM‐co‐DMI)) and poly[NIPAAM‐co‐(itaconic acid)] (P(NIPAAM‐co‐IA)) gels containing hydrophobic (DMI) and hydrophilic (IA) comonomers were prepared by free radical polymerization using potassium persulfate (KPS) –N, N, N′, N′‐tetramethyl ethylene diamine (TEMED) (redox initiator) in the presence of an N, N′‐methylene bis(acrylamide) (MBAAM) cross‐linking agent. The synthesis‐solvent composition (40/60 mixture of water/methanol and water) and initiator concentration employed significantly affected the properties of the NIPAAM gels. The transition temperatures of P(NIPAAM‐co‐IA) gels synthesized in water/methanol mixture were higher than that of the gel obtained in water. Furthermore, χ values of the NIPAAM homopolymer gel prepared with higher KPS content was an increasing function of temperature, while χ values of the sample obtained with lower initiator concentration changed around a critical solubility value 0.50. The results obtained also show that the interactions between monomer and solvent molecules in the reaction media (ie composition of the pregel solution) have an important effect on the formation and properties of the network structure (ie pore sizes of the gels). © 2000 Society of Chemical Industry

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Pharmaceutical Applications of Maleic Anhydride/Acid Copolymers

Popescu¹

2015

Handbook of Polymers for Pharmaceutical Technologies

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Investigation of the effect of type and concentration of ionizable comonomer on the collapse behavior ofN-isopropylacrylamide copolymer gels in water

Cited by 37 publications

References 29 publications

Effect of Network Density in Surface-Anchored Poly(N-isopropylacrylamide) Hydrogels on Adsorption of Fibrinogen

Effect of Network Density in Surface-Anchored Poly(N-isopropylacrylamide) Hydrogels on Adsorption of Fibrinogen

Effects of synthesis-solvent composition and initiator concentration on the swelling behaviour of poly(N-isopropylacrylamide) P(NIPAAM), poly(NIPAAM-co-dimethyl itaconate), and poly(NIPAAM-co itaconic acid) gels

Pharmaceutical Applications of Maleic Anhydride/Acid Copolymers

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