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Ruzzi V, Buzzaccaro S, Piazza R. Thermal Lens Measurements of Thermal Expansivity in Thermosensitive Polymer Solutions. Polymers (Basel) 2023; 15:polym15051283. [PMID: 36904524 PMCID: PMC10007145 DOI: 10.3390/polym15051283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 02/28/2023] [Accepted: 03/01/2023] [Indexed: 03/06/2023] Open
Abstract
The weak absorption of a laser beam generates in a fluid an inhomogeneous refractive index profile acting as a negative lens. This self-effect on beam propagation, known as Thermal Lensing (TL), is extensively exploited in sensitive spectroscopic techniques, and in several all-optical methods for the assessment of thermo-optical properties of simple and complex fluids. Using the Lorentz-Lorenz equation, we show that the TL signal is directly proportional to the sample thermal expansivity α, a feature allowing minute density changes to be detected with high sensitivity in a tiny sample volume, using a simple optical scheme. We took advantage of this key result to investigate the compaction of PniPAM microgels occurring around their volume phase transition temperature, and the temperature-driven formation of poloxamer micelles. For both these different kinds of structural transitions, we observed a significant peak in the solute contribution to α, indicating a decrease in the overall solution density-rather counterintuitive evidence that can nevertheless be attributed to the dehydration of the polymer chains. Finally, we compare the novel method we propose with other techniques currently used to obtain specific volume changes.
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Buratti E, Tavagnacco L, Zanatta M, Chiessi E, Buoso S, Franco S, Ruzicka B, Angelini R, Orecchini A, Bertoldo M, Zaccarelli E. The role of polymer structure on water confinement in poly(N-isopropylacrylamide) dispersions. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118924] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Tavagnacco L, Zaccarelli E, Chiessi E. Modeling Solution Behavior of Poly( N-isopropylacrylamide): A Comparison between Water Models. J Phys Chem B 2022; 126:3778-3788. [PMID: 35491838 PMCID: PMC9150113 DOI: 10.1021/acs.jpcb.2c00637] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
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Water is known to
play a fundamental role in determining the structure
and functionality of macromolecules. The same crucial contribution
is also found in the in silico description of polymer aqueous solutions.
In this work, we exploit the widely investigated synthetic polymer
poly(N-isopropylacrylamide) (PNIPAM) to understand
the effect of the adopted water model on its solution behavior and
to refine the computational setup. By means of atomistic molecular
dynamics simulations, we perform a comparative study of PNIPAM aqueous
solution using two advanced water models: TIP4P/2005 and TIP4P/Ice.
The conformation and hydration features of an atactic 30-mer at infinite
dilution are probed at a range of temperature and pressure suitable
to detect the coil-to-globule transition and to map the P–T
phase diagram. Although both water models can reproduce the temperature-induced
coil-to-globule transition at atmospheric pressure and the polymer
hydration enhancement that occurs with increasing pressure, the PNIPAM–TIP4P/Ice
solution shows better agreement with experimental findings. This result
can be attributed to a stronger interaction of TIP4P/Ice water with
both hydrophilic and hydrophobic groups of PNIPAM, as well as to a
less favorable contribution of the solvent entropy to the coil-to-globule
transition.
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Affiliation(s)
- Letizia Tavagnacco
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A, Moro 2, Rome 00185, Italy
| | - Emanuela Zaccarelli
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A, Moro 2, Rome 00185, Italy
| | - Ester Chiessi
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Via della Ricerca Scientifica I, Rome 00133, Italy
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Thermal Behaviour of Microgels Composed of Interpenetrating Polymer Networks of Poly( N-isopropylacrylamide) and Poly(acrylic acid): A Calorimetric Study. Polymers (Basel) 2021; 14:polym14010115. [PMID: 35012137 PMCID: PMC8747536 DOI: 10.3390/polym14010115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 12/23/2021] [Accepted: 12/26/2021] [Indexed: 12/17/2022] Open
Abstract
Stimuli-responsive microgels have recently attracted great attention in fundamental research as their soft particles can be deformed and compressed at high packing fractions resulting in singular phase behaviours. Moreover, they are also well suited for a wide variety of applications such as drug delivery, tissue engineering, organ-on-chip devices, microlenses fabrication and cultural heritage. Here, thermoresponsive and pH-sensitive cross-linked microgels, composed of interpenetrating polymer networks of poly(N-isopropylacrylamide) (PNIPAM) and poly(acrylic acid) (PAAc), are synthesized by a precipitation polymerization method in water and investigated through differential scanning calorimetry in a temperature range across the volume phase transition temperature of PNIPAM microgels. The phase behaviour is studied as a function of heating/cooling rate, concentration, pH and PAAc content. At low concentrations and PAAc contents, the network interpenetration does not affect the transition temperature typical of PNIPAM microgel in agreement with previous studies; on the contrary, we show that it induces a marked decrease at higher concentrations. DSC analysis also reveals an increase of the overall calorimetric enthalpy with increasing concentration and a decrease with increasing PAAc content. These findings are discussed and explained as related to emerging aggregation processes that can be finely controlled by properly changing concentration, PAAc content an pH. A deep analysis of the thermodynamic parameters allows to draw a temperature–concentration state diagram in the investigated concentration range.
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Tavagnacco L, Chiessi E, Zaccarelli E. Molecular insights on poly( N-isopropylacrylamide) coil-to-globule transition induced by pressure. Phys Chem Chem Phys 2021; 23:5984-5991. [PMID: 33666621 PMCID: PMC8247264 DOI: 10.1039/d0cp06452a] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 02/17/2021] [Indexed: 12/17/2022]
Abstract
By using extensive all-atom molecular dynamics simulations of an atactic linear polymer chain, we provide microscopic insights into poly(N-isopropylacrylamide) (PNIPAM) coil-to-globule transition addressing the roles played by both temperature and pressure. We detect a coil-to-globule transition up to large pressures, showing a reentrant behavior of the critical temperature with increasing pressure in agreement with experimental observations. Furthermore, again confirming the experimental findings, we report the existence at high pressures of a new kind of globular state. It is characterized by a more structured hydration shell that is closer to PNIPAM hydrophobic domains, as compared to the globular state observed at atmospheric pressure. Our results highlight that temperature and pressure induce a PNIPAM coil-to-globule transition through different molecular mechanisms, opening the way for a systematic use of both thermodynamic variables to tune the location of the transition and the properties of the associated swollen/collapsed states.
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Affiliation(s)
- Letizia Tavagnacco
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185, Rome, Italy.
| | - Ester Chiessi
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133, Rome, Italy.
| | - Emanuela Zaccarelli
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185, Rome, Italy.
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Di Napoli B, Franco S, Severini L, Tumiati M, Buratti E, Titubante M, Nigro V, Gnan N, Micheli L, Ruzicka B, Mazzuca C, Angelini R, Missori M, Zaccarelli E. Gellan Gum Microgels as Effective Agents for a Rapid Cleaning of Paper. ACS APPLIED POLYMER MATERIALS 2020; 2:2791-2801. [PMID: 32685926 PMCID: PMC7359273 DOI: 10.1021/acsapm.0c00342] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 05/27/2020] [Indexed: 05/21/2023]
Abstract
Microgel particles have emerged in the past few years as a favorite model system for fundamental science and for innovative applications ranging from the industrial to biomedical fields. Despite their potentialities, no works so far have focused on the application of microgels for cultural heritage preservation. Here we show their first use for this purpose, focusing on wet paper cleaning. Exploiting their retentive properties, microgels are able to clean paper, ensuring more controlled water release from the gel matrix, in analogy to their macroscopic counterpart, i.e., hydrogels. However, differently from these, the reduced size of microgels makes them suitable to efficiently penetrate in the porous structure of the paper and to easily adapt to the irregular surfaces of the artifacts. To test their cleaning abilities, we prepare microgels made of Gellan gum, a natural and widespread material already used as a hydrogel for paper cleaning, and apply them to modern and ancient paper samples. Combining several diagnostic methods, we show that microgels performances in the removal of cellulose degradation byproducts for ancient samples are superior to commonly employed hydrogels and water bath treatments. This is due to the composition and morphology of ancient paper, which facilitates microgels penetration. For modern paper cleaning, performances are at least comparable to the other methods. In all cases, the application of microgels takes place on a time scale of a few minutes, opening the way for widespread use as a rapid and efficient cleaning protocol.
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Affiliation(s)
- Benedetta Di Napoli
- Institute
for Complex Systems, National Research Council (CNR-ISC) and Department
of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
- Department
of Chemical Sciences and Technologies, University
of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133 Rome, Italy
| | - Silvia Franco
- Institute
for Complex Systems, National Research Council (CNR-ISC) and Department
of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
| | - Leonardo Severini
- Department
of Chemical Sciences and Technologies, University
of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133 Rome, Italy
| | - Manuel Tumiati
- Department
of Chemical Sciences and Technologies, University
of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133 Rome, Italy
| | - Elena Buratti
- Institute
for Complex Systems, National Research Council (CNR-ISC) and Department
of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
| | - Mattia Titubante
- Department
of Chemical Sciences and Technologies, University
of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133 Rome, Italy
| | - Valentina Nigro
- Institute
for Complex Systems, National Research Council (CNR-ISC) and Department
of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
- ENEA
C.R. Frascati, FSN-TECFIS-MNF
Photonics Micro and Nanostructures Laboratory, Via E. Fermi 45, 00044 Frascati, Roma, Italy
| | - Nicoletta Gnan
- Institute
for Complex Systems, National Research Council (CNR-ISC) and Department
of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
| | - Laura Micheli
- Department
of Chemical Sciences and Technologies, University
of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133 Rome, Italy
| | - Barbara Ruzicka
- Institute
for Complex Systems, National Research Council (CNR-ISC) and Department
of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
| | - Claudia Mazzuca
- Department
of Chemical Sciences and Technologies, University
of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133 Rome, Italy
| | - Roberta Angelini
- Institute
for Complex Systems, National Research Council (CNR-ISC) and Department
of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
| | - Mauro Missori
- Institute
for Complex Systems, National Research Council (CNR-ISC) and Department
of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
| | - Emanuela Zaccarelli
- Institute
for Complex Systems, National Research Council (CNR-ISC) and Department
of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
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