Single‐Chain‐Particles of Poly(<i>N</i>‐isopropylacrylamide)

Yan, Xiaobing; Cheng, Rongshi

doi:10.1002/marc.200290009

Cited by 12 publications

(9 citation statements)

References 14 publications

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“…This complex model was consistent with the previously proposed pearl-necklace-like complex structure of polymer and surfactant. , The cross-peaks indicated that the charged SDS molecules were in close proximity (<0.5 nm) to the polymer chains, which endows polyelectrolytic characteristics to the complexes of PNIPAM and SDS. Consequently, the hydrodynamic size of PNIPAM in the presence of SDS for intrachain electrostatic repulsion increased compared with that in surfactant-free solution, as also observed by previous studies. , On the other hand, the interchain electrostatic repulsions inhibited the interchain aggregation above the LCST to obtain the PNIPAM single-chain compact globule. , …”

Section: Resultssupporting

confidence: 81%

“…15,16 On the other hand, the interchain electrostatic repulsions inhibited the interchain aggregation above the LCST to obtain the PNIPAM single-chain compact globule. 31,32 In terms of the intensity changes of the cross-peaks with the SDS concentration, the signals of Pa−S2, Pa−S3, and Pa−S4 were obviously stronger with increased SDS concentration. To analyze the 2D NOESY spectra further, 1D spectra extracted from the Pa signal of the 2D NOESY spectra at 1.0 ppm are listed on the right side of each set in Figure 2b.…”

Section: Resultsmentioning

confidence: 99%

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Effect of Surfactant Concentration on the Complex Structure of Poly(N-isopropylacrylamide)/Sodium n-Dodecyl Sulfate in Aqueous Solutions

et al. 2012

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The effect of surfactant concentration on the complex structures of the thermosensitive poly(N-isopropylacrylamide) (PNIPAM) with sodium n-dodecyl sulfate (SDS) in dilute aqueous solutions and below the lower critical solution temperature were investigated using viscometry, two-dimensional nuclear Overhauser effect spectroscopy (2D NOESY), and pulsed-field gradient diffusion nuclear magnetic resonance (NMR). The interactions of PNIPAM and SDS were found to exhibit strong dependences on the SDS concentration. The amount of polymer-bound and free SDS at various SDS concentrations was calculated from the diffusion coefficients of SDS. At SDS concentrations below the critical aggregation concentration (CAC) of around 0.86 mM, the interaction between PNIPAM and SDS was very minimal, resulting in almost no change in the intrinsic viscosity and hydrodynamic size of the polymer. At SDS concentrations above 0.86 mM but below 7.0 mM, the intrinsic viscosity of the polymer as well as the amount of polymer-bound SDS and the intensities of the cross-peaks in the 2D NOESY NMR spectra all increased linearly with increased SDS concentration, resulting from enhanced interaction between PNIPAM and SDS. However, the amount of polymer-free SDS remained almost constant at around 0.86 mM near the CAC. At SDS concentrations above 7.0 mM, almost no more SDS was adsorbed onto PNIPAM and the amount of polymer-bound SDS remained constant, indicating the saturation of the PNIPAM chain with SDS.

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Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Effect of Surfactant Concentration on the Complex Structure of Poly(N-isopropylacrylamide)/Sodium n-Dodecyl Sulfate in Aqueous Solutions

et al. 2012

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“…On the other hand, the interchain electrostatic repulsions inhibit the interchain aggregation so that the PNIPAM single-chain compact globule can be obtained. 27,28 However, the noticeable change in the 2D NOESY spectra in Figure 3 shows the decrease in the signal intensity of the crosspeaks between PNIPAM and SDS with increasing temperature, although nearly half of the PNIPAM units are undetected in the NMR spectra above the LCST. Slice 1D spectra were extracted from the 2D NOESY spectra and are shown in the right list of Figure 3.…”

Section: Resultsmentioning

confidence: 99%

NMR Study on the Effects of Sodium n-Dodecyl Sulfate on the Coil-to-Globule Transition of Poly(N-isopropylacrylamide) in Aqueous Solutions

et al. 2011

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“…[ 27 ] In the study of Hu et al. [ 28 ] no inter‐chain entanglement was found in the single‐chain polymer particles, showing the solution process as a general method to achieve the disentangled polymers.…”

Section: Control Of Polymer Chain Entanglementmentioning

confidence: 99%

Control of Polymer Properties by Entanglement: A Review

Kong

Yang

Zhang

et al. 2021

Macro Materials & Eng

104

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Chain entanglement, either cohesional or topological, distinguishes polymers from other engineering materials. It impedes the movement of molecular segments and influences the polymer rheology, morphology, and mechanical properties. Although a high level of entanglement can increase the polymer toughness, excessive entanglement should be avoided because it causes a high melt viscosity making the processing difficult. This review tended to elucidate the influence of entanglement on the polymer structure, determining the material properties and processability. A wide range of methods used to fine control the degrees of chain entanglement are summarized. The methods are applicable to polymers in solutions, melts, and condensed states with advantages and limitations discussed in detail. The authors also examined the effect of the entanglement on polymer crystallization—the mechanism remains a controversial issue. This review will provide general guidance to designing and processing polymer materials with desired properties via a rational route of controlling the chain entanglement.

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Single‐Chain‐Particles of Poly(N‐isopropylacrylamide)

Cited by 12 publications

References 14 publications

Effect of Surfactant Concentration on the Complex Structure of Poly(N-isopropylacrylamide)/Sodium n-Dodecyl Sulfate in Aqueous Solutions

Effect of Surfactant Concentration on the Complex Structure of Poly(N-isopropylacrylamide)/Sodium n-Dodecyl Sulfate in Aqueous Solutions

NMR Study on the Effects of Sodium n-Dodecyl Sulfate on the Coil-to-Globule Transition of Poly(N-isopropylacrylamide) in Aqueous Solutions

Control of Polymer Properties by Entanglement: A Review

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