Studies of the “Smart” Thermoresponsive Behavior of Copolymers of N-Isopropylacrylamide and N,N-Dimethylacrylamide in Dilute Aqueous Solution

Barker, Ian C.; Cowie, J. M. G.; Huckerby, Thomas N.; Shaw, David; Soutar, Ian; Swanson, Linda

doi:10.1021/ma034250m

Cited by 129 publications

(133 citation statements)

References 32 publications

(110 reference statements)

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“…47,48 A breakdown of the hydrogen bonding between the polar units of the macromolecules and water, or changes to the 'hydrophobic effects' could be responsible for the coilto-globule transition. 49 Although thermo-responsive polymers have been extensively studied, the effects of salts on these polymers remain less well examined.…”

Section: Articlementioning

confidence: 99%

NMR investigation of effect of dissolved salts on the thermoresponsive behavior of oligo(ethylene glycol)-methacrylate-based polymers

Zhang

Peng

Whittaker

2014

J. Polym. Sci. Part A: Polym. Chem.

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The synthesis of thermo-and ionic-responsive copolymers based on polyethylene glycol methyl ether methacrylate (OEGMA) and 2,2,2-trifluoroethyl acrylate (TFEA) via reversible addition-fragmentation chain transfer polymerization is described. Reactivity ratios for the copolymerization of OEGMA and TFEA are r OEGMA 5 2.46 and r TFEA 5 0.22, indicating that OEGMA is incorporated more rapidly than TFEA monomers. The copolymers are thermosensitive and exhibit volume phase transitions (lower critical solution behavior) at temperature, which depend on copolymer composition and the presence of added salts in the aqueous solutions. It was found that the copolymers exhibited LCST transitions at temperatures below 353 K only in salt solutions.1 H NMR measurements indicated that motion of the protons located in and near the hydrophobic main chain are more sensitive to temperature than protons in the hydrophilic OEGMA side chains. The hydrophilic side chains remain largely hydrated; however, the presence of two distinct conformations of the terminal groups of the side chains was confirmed. The influence of OEGMA side chain length, copolymer composition, and salt type on aggregation behavior and dynamics was examined in detail.

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Section: Articlementioning

confidence: 99%

NMR investigation of effect of dissolved salts on the thermoresponsive behavior of oligo(ethylene glycol)-methacrylate-based polymers

Zhang

Peng

Whittaker

2014

J. Polym. Sci. Part A: Polym. Chem.

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“…Variations in the pyrene lifetime can also be used to monitor changes in thermoresponsive polymers. For aqueous solutions of PNIPAm one observes approximately a 60 ns increase in average lifetime from 115 ns to~175 ns as the temperature increases from 30 to 40 C [103]. Szczupak et al assessed the polarity of poly(NIPAm-coNtBA) copolymer films by means of fluorescence based methods, using pyrene and 3-HF derivatives as polarity sensitive fluorescent probes [100].…”

Section: Physicochemical Parameters By Fluorescencementioning

confidence: 99%

Fluorescence Analysis of Thermoresponsive Polymers

Morris

Ryder

2015

Reviews in Fluorescence

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The use of microscale thin polymer films is widespread in biomedical science and engineering, with applications in areas such as tissue engineering, drug delivery, microfluidic devices, bio-adhesion mediators, and bio-actuators. Much attention is devoted to the use of functional polymers that display stimuliresponsive behavior with the intention of providing "smart" coatings. One potential example is the use of thin thermoresponsive polymer films as drug eluting coatings on medical devices, where not only does the polymer function as a drug reservoir but it also acts as a biocompatibility modulator to improve device performance.Often these thin polymer coatings have to be applied to complex geometries, which can cause problems for in-situ analysis. Another important consideration is the fact that these films have large surface area to mass ratios and thus water uptake can be significant. This is serious because coating stability, device efficacy, and long-term storage are influenced by the physiochemical properties of the polymer which are modulated by water content. Thus, there is a need for a rapid, non-contact, non-destructive, analytical method capable of analyzing thermoresponsive polymers in solution, and in-situ of the solid-state on medical devices. Fluorescence spectroscopy based methods can deal with both sample types and provide additional benefits in terms of high sensitivity and low probe concentrations, which provide for minimal sample disruption. This article gives a brief overview of the application of various fluorescence methods for the physicochemical characterization of thermoresponsive polymers such as poly (N-isopropylacrylamide), PNIPAm.

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“…It has been well established that the thermal response of such polymers is due to a two-stage mechanism: individual chain collapse, in a coil-globule transition, prior to aggregation of the resultant globules. [32] Two factors have been thought to contribute to the coil-to-globule transition, which include the breakdown of polymer-water hydrogen bonding in controlling the macromolecular contraction, or chain collapse to changes in the hydrophobic effect, or both. [33,34] Furthermore, T 1 values of N-isopropyl groups decreased with increasing PBLG content in GN diblock copolymer, suggesting that the mobility of PNIPAAm chain, as the shell, becomes more restricted at higher PBLG core content.…”

Section: Measurement Of Spin-lattice Relaxation Time (T 1 )mentioning

confidence: 99%

Effect of Temperature on the Mobility of Core‐Shell‐Type Nanoparticles Composed of Poly(γ‐benzyl‐L‐glutamate) and Poly(N‐isopropylacrylamide)

Yoo

Jang

Nah

et al. 2006

Macro Chemistry & Physics

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IntroductionPolymers that show phase transition in water upon raising the temperature above a critical point, termed lower critical solution temperature (LCST), have attracted much attention in many areas of modern science and engineering. Among these polymers, poly(N-isopropylacrylamide) (PNIPAAm) is the most popular temperature-sensitive polymer due to its dramatic and reversible transition behavior at around 32 8C. [1,2] Most work on the phase transition of PNIPAAm has so far been limited to the measurements on the macroscopic quantities, although many methods including cloud point measurement, [3] light scattering, [2] DSC, [4] and fluorescence [5] have been used.NMR relaxation times, i.e., spin-lattice relaxation time (T 1 ) and spin-spin relaxation time (T 2 ), and a linewidth give useful information on the microscopic molecular motion of water and polymer in solutions. [6][7][8] Applying NMR technique to study the phase transition of PNIPAAm, Tokuhiro et al. [9] measured T 1 of nonionic and ionic PNIPAAm gels in D 2 O and made a complete interpretation on the dynamics of the side and backbone chains through the phase transition process. In addition, a few researchers reported on the dynamics of PNIPAAm gel, polymer, and water molecules Summary: Core-shell-type nanoparticles composed of PBLG and PNIPAAm were prepared in an attempt to study the effects of temperature on the dynamic behavior of temperature-sensitive polymeric shell, PNIPAAm, in the nanoparticles by 1 H NMR spectroscopy. Spin-lattice relaxation time (T 1 ) and line halfwidth in D 2 O and CDCl 3 were measured to monitor the change of the chain mobility of PNIPAAm in the GN nanoparticles within the temperature range encompassing its LCST. The molecular motion of PBLG segment in GN nanoparticles in CDCl 3 was also examined and compared with that of the PNIPAAm. The morphology, size distribution, and effect of temperature on the sizes of the GN nanoparticles were also investigated. The temperature dependence of T 1 and line halfwidth suggests that the N-isopropyl group turns gradually into the solid-like aggregates at temperatures higher than the LCST of PNIPAAm due to the collapsed coil-globule transition. T 1 values of N-isopropyl groups decreased with increasing PBLG content in GN diblock copolymer, suggesting the mobility of PNIPAAm chain, as the shell, becomes more restricted at higher PBLG core content.Changes in the mobility of PNIPAAm shell in the core-shelltype nanoparticles composed of PBLG and PNIPAAm.

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Studies of the “Smart” Thermoresponsive Behavior of Copolymers of N-Isopropylacrylamide and N,N-Dimethylacrylamide in Dilute Aqueous Solution

Cited by 129 publications

References 32 publications

NMR investigation of effect of dissolved salts on the thermoresponsive behavior of oligo(ethylene glycol)-methacrylate-based polymers

NMR investigation of effect of dissolved salts on the thermoresponsive behavior of oligo(ethylene glycol)-methacrylate-based polymers

Fluorescence Analysis of Thermoresponsive Polymers

Effect of Temperature on the Mobility of Core‐Shell‐Type Nanoparticles Composed of Poly(γ‐benzyl‐L‐glutamate) and Poly(N‐isopropylacrylamide)

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