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Your search keyword '"Raffa, Patrizio"' showing total 192 results
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192 results on '"Raffa, Patrizio"'

3. Synthesis and Properties of a Shape Memory–Assisted Self‐Healing Supramolecular Polyurethane Coating Based on Quadrupole Hydrogen Bonding.

Author

Karimi Alavijeh, Soheila, Khorasani, Saied Nouri, Masoomi, Mahmood, Neisiany, Rasoul Esmaeely, Dinari, Mohammad, Gomes, Diego Ribas, Pei, Yutao, and Raffa, Patrizio

Subjects
METHYLENE diphenyl diisocyanate, HYDROGEN bonding interactions, HYDROGEN bonding, DIFFERENTIAL scanning calorimetry, POLYETHYLENE glycol
Abstract

In this research, the synthesis and characterization of a shape memory–assisted self‐healing polyurethane (SHSMPU) coating based on strong quadrupole hydrogen bonding interaction have been investigated. The coating was fabricated with an acrylic polyol, an isocyanate functionalized ureidopyrimidinone (UPy‐NCO) as a hydrogen bonding provider, and methylene diphenyl diisocyanate (MDI) as chain extender. Fourier‐transform infrared spectroscopy (FT‐IR) confirmed that by incorporating the UPy‐NCO dimer in the polyurethane (PU) structure, strong hydrogen bonding appears, which can provide the healing function of the polymer. In addition, differential scanning calorimetry (DSC) showed that by increasing the UPy‐NCO amount, the overall Tg decreased and the material becomes more flexible. A rheometric investigation revealed that a sample containing 45% of UPy‐NCO as total diisocyanate shows good shape recovery and an healing efficiency of macroscale cracks of around 94.2%, which is much higher than the corresponding sample without UPy‐NCO (50.4%). Even better performances were obtained with microcracks, where tested samples were significantly healed at around 80°C in 10 min. Furthermore, the introduction of polyethylene glycol 400 (PEG400) into the polymer's backbone led to a reduced Tg and thus higher flexibility at room temperature. The combination of the observed properties makes these materials promising for application as durable and flexible polyurethane coatings. [ABSTRACT FROM AUTHOR]

Published
2024
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9. Homogeneous Reversible Addition Fragmentation Chain Transfer Synthesis of Amphiphilic Poly(Styrene-b-Acrylamide) Copolymers and Their Solution Characterization: a Thermogelating and Salinity Resistant Viscosifier from Largely Available Monomers

Author

Guzik, Aleksander, Koot, Olivia F., Stuart, Marc C.A., and Raffa, Patrizio

Abstract

Even though styrene and acrylamide are among the most abundant monomers, their copolymers are understudied due to the difficulties connected to their synthesis, especially if well-defined structures are desired. This study explores the synthesis and solution properties of poly(styrene-b-acrylamide) block copolymers. We report for the first time the synthesis of such diblock copolymers with RAFT polymerization in homogeneous conditions, utilizing DMSO as a common solvent. Despite their nonpolyelectrolyte nature and a very low content of the hydrophobic comonomer, poly(styrene-b-acrylamide) diblock copolymers have been found to be remarkably good viscosifiers for water. Gelation concentration as low as 1 wt % was observed for copolymers containing as little as 1 mol % of styrene constituting a block less than 10 repeat units long. An irreversible gelation upon heating was observed according to a new mechanism of microgel particle hydration, which is proposed for applications in the fields of biomaterials and 3D printing. The properties are speculated to arise from strong hydrogen bonding within the PAM domains. Amid the current growing focus on polyelectrolytes, this work highlights ubiquitous acrylamide as a building block in nonpolyelectrolyte block copolymers for design of smart soft materials.

Published
2024
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17. Lactic Acid-Derived Copolymeric Surfactants with Monomer Distribution Profile-Dependent Solution and Thermoresponsive Properties

Author

Universitat Rovira i Virgili, Migliore, Nicola; Guzik, Aleksander; Stuart, Marc C. A.; Pala, Marc; Moreno, Adrian; Lligadas, Gerard; Raffa, Patrizio, Universitat Rovira i Virgili, and Migliore, Nicola; Guzik, Aleksander; Stuart, Marc C. A.; Pala, Marc; Moreno, Adrian; Lligadas, Gerard; Raffa, Patrizio

Abstract

We report the synthesis and solution properties of novel biobased thermoresponsive amphiphilic copolymers prepared using N,N-dimethyl lactamide acrylate (DMLA) and ethyl lactate acrylate (ELA) as hydrophilic and hydrophobic monomers, respectively. Copolymers with similar overall molecular weight but different monomer distribution profiles, such as random, diblock, triblock, and random-blocks, were prepared using photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization activated by a Zn-based photoredox catalyst. The synthesized polymers show interesting self-assembly and thermores-ponsive behavior in water, depending on the monomers distribution along the chain. Different critical solution temperatures, in the range of 13-70 degrees C, were observed by tuning the monomers molar ratio and distribution. The formation of aggregates of various types was proven by transmission electron microscopy (TEM). The prepared polymers also display different surface activity with the fully random copolymer being significantly more surface active than block systems. A study of emulsion stabilization was performed with oils of various polarity, showing promising results for applications of these novel polymers as biobased surfactants and water/oil (w/o) emulsion stabilizers.

Published
2022

19. Transparent, Highly Stretchable, Self‐Healing, Adhesive, Freezing‐Tolerant, and Swelling‐Resistant Multifunctional Hydrogels for Underwater Motion Detection and Information Transmission (Adv. Funct. Mater. 49/2024).

Author

Zhang, Zeyu, Yao, Aifang, and Raffa, Patrizio

Subjects
FLEXIBLE electronics, HYDROPHOBIC interactions, PATIENT monitoring, SOLVENTS, ADHESIVES
Abstract

The article "Transparent, Highly Stretchable, Self-Healing, Adhesive, Freezing-Tolerant, and Swelling-Resistant Multifunctional Hydrogels for Underwater Motion Detection and Information Transmission" in Advanced Functional Materials discusses the development of conductive hydrogels with unique properties for underwater sensing. The hydrogels are created using hydrophobic interactions and a deep eutectic solvent, making them self-healing and suitable for underwater environments. The authors suggest potential applications in underwater sensors, communication devices, medical monitoring, and structural monitoring. [Extracted from the article]

Published
2024
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23. Design and Synthesis of Low Molecular Weight and Polymeric Surfactants for Enhanced Oil Recovery

Author

Solling, Theis, Kamal, Shahzad, Hussain, Syed Shakil, Raffa, Patrizio, Solling, Theis, Kamal, Shahzad, Hussain, Syed Shakil, and Raffa, Patrizio

Abstract

Surfactants are defined as molecules able to lower the surface (or interfacial) tension at the gas/liquid, liquid/liquid, and liquid/solid interfaces. Due to their properties, they are typically employed as detergents, emulsifiers, dispersants, wetting and foaming agents. In chemical enhanced oil recovery (cEOR), surfactants are used as flooding agents, alone or in combination with polymers, alkali, and more recently nanoparticles, to increase the microscopic displacement efficiency. From a chemical point of view, surfactants are amphiphiles, meaning that they bear in their structure both hydrophilic and hydrophobic moieties. Some naturally occurring surfactants exists, but the majority are synthetic. The availability of synthetic surfactants, allows a big variety of structures and properties. In this chapter, the main classes of surfactants will be reviewed, with focus on those used or proposed for use for chemical enhanced oil recovery. After a general introduction about surfactants and their main structural and physico-chemical properties, specific aspects of design and synthesis will be discussed. Particular emphasis will be given to the most recent developments, which includes zwitterionic, gemini and polymeric surfactants. Own work of the author of this chapter in the field of polymeric surfactants will be highlighted.

Published
2021

32. Chemical Enhanced Oil Recovery

Author

Raffa, Patrizio, Druetta, Pablo, and Product Technology

Abstract

This book aims at presenting, describing, and summarizing the latest advances in polymer flooding regarding the chemical synthesis of the EOR agents and the numerical simulation of compositional models in porous media, including a description of the possible applications of nanotechnology acting as a booster of traditional chemical EOR processes. A large part of the world economy depends nowadays on non-renewable energy sources, most of them of fossil origin. Though the search for and the development of newer, greener, and more sustainable sources have been going on for the last decades, humanity is still fossil-fuel dependent. Primary and secondary oil recovery techniques merely produce up to a half of the Original Oil In Place. Enhanced Oil Recovery (EOR) processes are aimed at further increasing this value. Among these, chemical EOR techniques (including polymer flooding) present a great potential in low- and medium-viscosity oilfields.

Published
2019
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39. Synthesis of poly(1‐vinylimidazole)‐block‐poly(9‐vinylcarbazole) copolymers via RAFTand their use in chemically responsive graphitic composites

Author

Migliore, Nicola, Araya‐Hermosilla, Esteban, Scheutz, Georg M., Sumerlin, Brent S., Pucci, Andrea, and Raffa, Patrizio

Abstract

This study reports the synthesis of novel poly(1‐vinylimidazole)‐b‐poly(9‐vinylcarbazole) (PVI‐b‐PVK) block copolymers with varying monomer ratios using reversible addition‐fragmentation chain‐transfer (RAFT) polymerization and their incorporation in responsive composite materials. Specifically, non‐covalent exfoliation of two different conductive fillers, multi‐walled carbon nanotubes (MWCNTs) or reduced graphene oxide (rGO), was studied. The percolation threshold of the synthesized nanocomposites was dependent on the polymer used for dispersion, showing a better affinity of the fillers for block copolymers with higher relative carbazole content. Resistivity measurements showed selective variation in the resistance signal when the materials were exposed to various organic solvents and acids, providing a good basis for the design of sensing devices.

Published
2022
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40. Design and synthesis of novel di‐ and triblock amphiphilic polyelectrolytes: Improving salt‐induced viscosity reduction of water solutions for potential application in enhanced oil recovery.

Author

Boulif, Nadia, Sebakhy, Khaled O., Joosten, Hidde, and Raffa, Patrizio

Subjects
DIBLOCK copolymers, ENHANCED oil recovery, POLYELECTROLYTES, THERMORESPONSIVE polymers, BLOCK copolymers, THICKENING agents, GLYCIDYL methacrylate
Abstract

In the present study, three different block copolymers based on styrene, tert‐butyl methacrylate, and glycidyl methacrylate (GMA) were synthesized via sequential atom transfer radical polymerization. The addition of the GMA block was found to be best performed at 60°C. The polymers were then hydrolyzed and neutralized, to afford amphiphilic block copolymers, and the rheological properties of their aqueous solutions were measured, in order to investigate solution properties relevant for enhanced oil recovery, as a function of the polymer structure. It was observed that these polymers behave as thickening agents with shear thinning behavior. As expected, the polymers were sensitive to the presence of salt, as lower viscosities were recorded in saline water. However, the viscosity is less affected by high salinity, when compared to previously studied analogous diblock systems. In the best case, the viscosity only decreased by a factor of 1.8 upon salt addition whereas it decreased by a factor of 10 in previously reported non‐GMA containing polymers. Finally, thermo‐responsive behavior was found for one of the synthesized polymers. In particular, a hydrolyzed triblock poly[styrene‐b‐tert‐butyl methacrylate‐b‐glycidyl methacrylate], which synthesis is reported here for the first time, showed a thermothickening behavior, promising for the intended application in oil recovery. [ABSTRACT FROM AUTHOR]

Published
2021
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