Two-step volume phase transition mechanism of poly(N-vinylcaprolactam) hydrogel online-tracked by two-dimensional correlation spectroscopy

2017 ◽  
Vol 19 (40) ◽  
pp. 27221-27232 ◽  
Author(s):  
Gehong Su ◽  
Tao Zhou ◽  
Xifei Liu ◽  
Yulin Zhang
Keyword(s):  
Phase Transition ◽  
Ftir Spectroscopy ◽  
Correlation Spectroscopy ◽  
Volume Phase Transition ◽  
Two Dimensional ◽  
Volume Phase ◽  
Transition Mechanism ◽  
Step Mechanism

The volume phase transition of PVCL hydrogel was online-tracked by 2D correlation FTIR spectroscopy, and a two-step mechanism was proposed.

Micro-dynamics mechanism of the phase transition behavior of poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate) hydrogels revealed by two-dimensional correlation spectroscopy

2017 ◽  
Vol 8 (5) ◽  
pp. 865-878 ◽  
Author(s):  
Gehong Su ◽  
Tao Zhou ◽  
Xifei Liu ◽  
Yanan Ma
Keyword(s):  
Phase Transition ◽  
Ftir Spectroscopy ◽  
Correlation Spectroscopy ◽  
Volume Phase Transition ◽  
Hydroxyethyl Methacrylate ◽  
Two Dimensional ◽  
Phase Transition Behavior ◽  
Temperature Dependent ◽  
Volume Phase ◽  
Transition Behavior

The micro-dynamics mechanism of the volume phase transition of PNIPAM-co-HEMA hydrogels was established using temperature-dependent FTIR spectroscopy, PCMW2D, and 2DCOS analysis.

scholarly journals Two-step deswelling in the Volume Phase Transition of thermoresponsive microgels

2021 ◽  
Vol 118 (37) ◽  
pp. e2109560118
Author(s):  
Giovanni Del Monte ◽  
Domenico Truzzolillo ◽  
Fabrizio Camerin ◽  
Andrea Ninarello ◽  
Edouard Chauveau ◽  
...  
Keyword(s):  
Phase Transition ◽  
Condensed Matter ◽  
Volume Phase Transition ◽  
Soft Condensed Matter ◽  
Volume Phase ◽  
Biomedical Technologies ◽  
Fundamental Phenomenon ◽  
Soft Colloids ◽  
Step Mechanism

Thermoresponsive microgels are one of the most investigated types of soft colloids, thanks to their ability to undergo a Volume Phase Transition (VPT) close to ambient temperature. However, this fundamental phenomenon still lacks a detailed microscopic understanding, particularly regarding the presence and the role of charges in the deswelling process. This is particularly important for the widely used poly(N-isopropylacrylamide)–based microgels, where the constituent monomers are neutral but charged groups arise due to the initiator molecules used in the synthesis. Here, we address this point combining experiments with state-of-the-art simulations to show that the microgel collapse does not happen in a homogeneous fashion, but through a two-step mechanism, entirely attributable to electrostatic effects. The signature of this phenomenon is the emergence of a minimum in the ratio between gyration and hydrodynamic radii at the VPT. Thanks to simulations of microgels with different cross-linker concentrations, charge contents, and charge distributions, we provide evidence that peripheral charges arising from the synthesis are responsible for this behavior and we further build a universal master curve able to predict the two-step deswelling. Our results have direct relevance on fundamental soft condensed matter science and on applications where microgels are involved, ranging from materials to biomedical technologies.

scholarly journals The Study of pH Effects on Phase Transition of Multi-Stimuli Responsive P(NiPAAm-co-AAc) Hydrogel Using 2D-COS

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1447
Author(s):  
Yeonju Park ◽  
Minkyoung Kim ◽  
Hae-jin Chung ◽  
Ah-hyun Woo ◽  
Isao Noda ◽  
...  
Keyword(s):  
Phase Transition ◽  
Principal Component ◽  
Correlation Spectroscopy ◽  
Cooh Group ◽  
Ph Effects ◽  
Two Dimensional ◽  
Stimuli Responsive ◽  
Stimuli Responsive Polymers ◽  
Transition Mechanism ◽  
Gradient Mapping

The temperature and mechanism of phase transition of poly(N-isopropylacrylamide-co-acrylic acid) [P(NiPAAm-co-AAc)], which is one of the multi-stimuli responsive polymers, were investigated at various pHs using infrared (IR) spectroscopy, two-dimensional (2D) gradient mapping, and two-dimensional correlation spectroscopy (2D-COS). The determined phase transition temperature of P(NiPAAm-co-AAc) at pH 4, 3, and 2 based on 2D gradient mapping and principal component analysis (PCA) showed that it decreases with decreasing pH, because COOH group in AAc changes with variation of pH. The results of 2D-COS analysis indicated that the phase transition mechanism of P(NiPAAm-co-AAc) hydrogel at pH4 is different from that at pH2 due to the effect of COOH group of AAc.

scholarly journals Deuteration-Induced Volume Phase Transition Temperature Shift of PNIPMAM Microgels

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 620 ◽  
Author(s):  
Marian Cors ◽  
Lars Wiehemeier ◽  
Julian Oberdisse ◽  
Thomas Hellweg
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Aqueous Suspension ◽  
Temperature Shift ◽  
Correlation Spectroscopy ◽  
Volume Phase Transition ◽  
Spatial Homogeneity ◽  
Volume Phase ◽  
Volume Phase Transition Temperature

The effect of deuteration on the volume phase transition (VPT) temperature of poly (N-isopropylmethacrylamide) (pNIPMAM) microgels in aqueous suspension is determined via IR spectroscopy and size measurements by photon correlation spectroscopy (PCS). We study the effect of a hydrogenated and a deuterated solvent (H2O/D2O), and of the hydrogenated and (partially) deuterated monomer. Deuteration of the monomer or copolymerization with deuterated monomers shifts the volume phase transition temperature (VPTT) by up to 8.4 K to higher temperatures, in good agreement with known results for pNIPAM microgels. Moreover, the shape of the swelling curve is found to depend on deuteration, with the highest deuteration leading to the sharpest VPT. Finally, the quantitative agreement between FTIR spectroscopy and PCS evidences the spatial homogeneity of the microgel particles. Our results are rationalized in terms of the effect of deuteration on hydrogen bonding. They shall be of primary importance for any experimental measurements close to the VPT involving isotopic substitution, and in particular contrast variation small angle neutron scattering.

Volume phase transition mechanism of poly[oligo(ethylene glycol)methacrylate] based thermo-responsive microgels with poly(ionic liquid) cross-linkers

2015 ◽  
Vol 17 (38) ◽  
pp. 25525-25535 ◽  
Author(s):  
Yuanyuan Zhou ◽  
Hui Tang ◽  
Peiyi Wu
Keyword(s):  
Phase Transition ◽  
Ionic Liquid ◽  
Fourier Transform ◽  
Ethylene Glycol ◽  
Cross Linking ◽  
Volume Phase Transition ◽  
Glycol Methacrylate ◽  
Volume Phase ◽  
Transition Mechanism ◽  
Poly Ionic Liquid

Thermodynamic volume phase transition mechanisms of poly[oligo(ethylene glycol)methacrylate] (POEGMA) microgels with poly(ionic liquid) (PIL) cross-linking moieties were investigated in detail on the basis of Fourier transform infrared (FTIR) spectroscopy.

Exploration of the unusual two-step volume phase transition of the poly(N-vinylcaprolactam-co-hydroxyethyl methacrylate) hydrogel

2018 ◽  
Vol 20 (35) ◽  
pp. 23013-23024 ◽  
Author(s):  
Gehong Su ◽  
Liyang Jia ◽  
Xueqian Zhang ◽  
Yulin Zhang ◽  
Pengchi Deng ◽  
...  
Keyword(s):  
Phase Transition ◽  
Biomedical Applications ◽  
Volume Phase Transition ◽  
Hydroxyethyl Methacrylate ◽  
Volume Phase ◽  
Transition Mechanism ◽  
Stimuli Sensitive

It is important to investigate the phase transition mechanism of stimuli-sensitive hydrogels due to its great guiding significance for the application of stimuli-sensitive hydrogels in biomedical applications.

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