scholarly journals Thermoresponsive Polymers of Poly(2-(N-alkylacrylamide)ethyl acetate)s

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2464
Author(s):  
Xue Liu ◽  
Yuwen Hou ◽  
Yimin Zhang ◽  
Wangqing Zhang
Keyword(s):  
Ethyl Acetate ◽  
Raft Polymerization ◽  
Polymer Concentration ◽  
Degree Of Polymerization ◽  
Random Copolymers ◽  
Solution Temperature ◽  
Thermoresponsive Polymers ◽  
Induction Periods ◽  
Alkyl Groups ◽  
Cloud Point Temperature

Thermoresponsive poly(2-(N-alkylacrylamide) ethyl acetate)s with different N-alkyl groups, including poly(2-(N-methylacrylamide) ethyl acetate) (PNMAAEA), poly(2-(N-ethylacrylamide) ethyl acetate) (PNEAAEA), and poly(2-(N-propylacrylamide) ethyl acetate) (PNPAAEA), as well as poly(N-acetoxylethylacrylamide) (PNAEAA), were synthesized by solution RAFT polymerization. Unexpectedly, it was found that there are induction periods in the RAFT polymerization of these monomers, and the induction time correlates with the length of the N-alkyl groups in the monomers and follows the order of NAEAA < NMAAEA < NEAAEA < NPAAEA. The solubility of poly(2-(N-alkylacrylamide) ethyl acetate)s in water is also firmly dependent on the length of the N-alkyl groups. PNPAAEA including the largest N-propyl group is insoluble in water, whereas PNMAAEA and PNEAAEA are thermoresponsive in water and undergo the reversible soluble-to-insoluble transition at a critical solution temperature. The cloud point temperature (Tcp) of the thermoresponsive polymers is in the order of PNEAAEA < PNAEAA < PNMAAEA. The parameters affecting the Tcp of thermoresponsive polymers, e.g., degree of polymerization (DP), polymer concentration, salt, urea, and phenol, are investigated. Thermoresponsive PNMAAEA-b-PNEAAEA block copolymer and PNMAAEA-co-PNEAAEA random copolymers with different PNMAAEA and/or PNEAAEA fractions are synthesized, and their thermoresponse is checked.

scholarly journals Thermal Behaviour of Common Thermoresponsive Polymers in Phosphate Buffer and in Its Salt Solutions

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 90
Author(s):  
Łukasz Otulakowski ◽  
Maciej Kasprów ◽  
Aleksandra Strzelecka ◽  
Andrzej Dworak ◽  
Barbara Trzebicka
Keyword(s):  
Thermal Behaviour ◽  
Phosphate Buffer ◽  
Pure Water ◽  
Thermal Response ◽  
The Body ◽  
Solution Temperature ◽  
Thermoresponsive Polymers ◽  
Aqueous Polymer ◽  
Cloud Point Temperature ◽  
Size Of Particles

Thermoresponsive polymers are a promising material for drug nanocarrier preparation, which makes the study of their aggregation in physiological conditions very important. In this paper, the thermal behaviour of the thermoresponsive polymers poly(N-isopropylacrylamide), poly(2-isopropyl-2-oxazoline-co-2-n-propyl-2-oxazoline) and poly[(2-hydroxyethyl methacrylate)-co-oligo(ethylene glycol) methyl ether methacrylate] were studied in phosphate buffer (PBS) and solutions of its salts in concentration as in PBS. The thermal response of the polymers was measured using UV-Vis and dynamic light scattering (DLS). The salts shifted the cloud point temperature (TCP) of the (co)polymers to higher values compared to the TCP of aqueous polymer solutions. In PBS and NaCl solutions, all polymers exhibited an unexpected and previously unreported transmittance profile. During heating, an additional aggregation of polymers appeared above the TCP accompanied by the formation of a precipitate. In monosodium phosphate solutions and pure water, the studied polymers showed lower critical solution temperature (LCST-type) behaviour. DLS measurements showed that a salt influenced the size of the resulting polymer particles. The sizes and stability of particles depended on the heating rate. In PBS and NaCl solutions, the size of particles in the dispersion decreased above 60 °C, and the precipitate appeared on the bottom of the cuvette. The additional aggregation of polymer and its falling out of solution may hinder the removal of carriers from the body and has to be taken into account when preparing nanocarriers.

scholarly journals Upper Critical Solution Temperature (UCST) Behavior of Polystyrene-Based Polyampholytes in Aqueous Solution

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 265 ◽  
Author(s):  
Komol Kanta Sharker ◽  
Yuki Ohara ◽  
Yusuke Shigeta ◽  
Shinji Ozoe ◽  
Shin-ichi Yusa
Keyword(s):  
Pure Water ◽  
Polymer Concentration ◽  
Degree Of Polymerization ◽  
Solution Temperature ◽  
Sulfonate Group ◽  
Trimethylammonium Chloride ◽  
Critical Solution Temperature ◽  
Reversible Addition ◽  
Upper Critical Solution Temperature ◽  
Quaternary Ammonium Group

Strong polyampholytes comprising cationic vinylbenzyl trimethylammonium chloride (VBTAC) bearing a pendant quaternary ammonium group and anionic sodium p-styrenesulfonate (NaSS) bearing a pendant sulfonate group were prepared via reversible addition-fragmentation chain-transfer polymerization. The resultant polymers are labelled P(VBTAC/NaSS)n, where n indicates the degree of polymerization (n = 20 or 97). The percentage VBTAC content in P(VBTAC/NaSS)n is always about 50 mol%, as revealed by 1H NMR measurements, meaning that P(VBTAC/NaSS)n is a close to stoichiometrically charge-neutralized polymer. Although P(VBTAC/NaSS)n cannot dissolve in pure water at room temperature, the addition of NaCl or heating solubilizes the polymers. Furthermore, P(VBTAC/NaSS)n exhibits upper critical solution temperature (UCST) behavior in aqueous NaCl solutions. The UCST is shifted to higher temperatures by increasing the polymer concentration and molecular weight, and by decreasing the NaCl concentration. The UCST behavior was measured ranging the polymer concentrations from 0.5 to 5.0 g/L.

scholarly journals Random and Diblock Thermoresponsive Oligo(ethylene glycol)-Based Copolymers Synthesized via Photo-Induced RAFT Polymerization

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 137
Author(s):  
Alexey Sivokhin ◽  
Dmitry Orekhov ◽  
Oleg Kazantsev ◽  
Olga Sivokhina ◽  
Sergey Orekhov ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Room Temperature ◽  
Raft Polymerization ◽  
Chain Extension ◽  
Random Copolymers ◽  
Hydrophobic Core ◽  
Polymer Backbone ◽  
Alkyl Groups ◽  
Green Led ◽  
A Chain

Amphiphilic random and diblock thermoresponsive oligo(ethylene glycol)-based (co)polymers were synthesized via photoiniferter polymerization under visible light using trithiocarbonate as a chain transfer agent. The effect of solvent, light intensity and wavelength on the rate of the process was investigated. It was shown that blue and green LED light could initiate RAFT polymerization of macromonomers without an exogenous initiator at room temperature, giving bottlebrush polymers with low dispersity at sufficiently high conversions achieved in 1–2 h. The pseudo-living mechanism of polymerization and high chain-end fidelity were confirmed by successful chain extension. Thermoresponsive properties of the copolymers in aqueous solutions were studied via turbidimetry and laser light scattering. Random copolymers of methoxy- and alkoxy oligo(ethylene glycol) methacrylates of a specified length formed unimolecular micelles in water with a hydrophobic core consisting of a polymer backbone and alkyl groups and a hydrophilic oligo(ethylene glycol) shell. In contrast, the diblock copolymer formed huge multimolecular micelles.

scholarly journals Synthesis and Characterization of Temperature-Responsive N-Cyanomethylacrylamide-Containing Diblock Copolymer Assemblies in Water

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4424
Author(s):  
Nicolas Audureau ◽  
Fanny Coumes ◽  
Clémence Veith ◽  
Clément Guibert ◽  
Jean-Michel Guigner ◽  
...  
Keyword(s):  
Diblock Copolymer ◽  
Self Assembly ◽  
Diblock Copolymers ◽  
Colloidal Stability ◽  
Aqueous Dispersion ◽  
Degree Of Polymerization ◽  
Solution Temperature ◽  
Thermoresponsive Polymers ◽  
Aqueous Synthesis ◽  
Reversible Addition

We have previously demonstrated that poly(N-cyanomethylacrylamide) (PCMAm) exhibits a typical upper-critical solution temperature (UCST)-type transition, as long as the molar mass of the polymer is limited, which was made possible through the use of reversible addition-fragmentation chain transfer (RAFT) radical polymerization. In this research article, we use for the first time N-cyanomethylacrylamide (CMAm) in a typical aqueous dispersion polymerization conducted in the presence of poly(N,N-dimethylacrylamide) (PDMAm) macroRAFT agents. After assessing that well-defined PDMAm-b-PCMAm diblock copolymers were formed through this aqueous synthesis pathway, we characterized in depth the colloidal stability, morphology and temperature-responsiveness of the dispersions, notably using cryo-transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and turbidimetry. The combined analyses revealed that stable nanometric spheres, worms and vesicles could be prepared when the PDMAm block was sufficiently long. Concerning the thermoresponsiveness, only diblocks with a PCMAm block of a low degree of polymerization (DPn,PCMAm < 100) exhibited a UCST-type dissolution upon heating at low concentration. In contrast, for higher DPn,PCMAm, the diblock copolymer nano-objects did not disassemble. At sufficiently high temperatures, they rather exhibited a temperature-induced secondary aggregation of primary particles. In summary, we demonstrated that various morphologies of nano-objects could be obtained via a typical polymerization-induced self-assembly (PISA) process using PCMAm as the hydrophobic block. We believe that the development of this aqueous synthesis pathway of novel PCMAm-based thermoresponsive polymers will pave the way towards various applications, notably as thermoresponsive coatings and in the biomedical field.

scholarly journals RAFT Emulsion Polymerization of Styrene Using a Poly((N,N-dimethyl acrylamide)-co-(N-isopropyl acrylamide)) mCTA: Synthesis and Thermosensitivity

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 62
Author(s):  
Katharina Nieswandt ◽  
Prokopios Georgopanos ◽  
Martin Held ◽  
Evgeni Sperling ◽  
Volker Abetz
Keyword(s):  
Emulsion Polymerization ◽  
Diblock Copolymers ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Molar Fraction ◽  
Solution Temperature ◽  
Hydrophobic Core ◽  
Spherical Micelle ◽  
Thermoresponsive Polymers ◽  
Isopropyl Acrylamide

Thermoresponsive poly((N,N-dimethyl acrylamide)-co-(N-isopropyl acrylamide)) (P(DMA-co-NIPAM)) copolymers were synthesized via reversible addition−fragmentation chain transfer (RAFT) polymerization. The monomer reactivity ratios were determined by the Kelen–Tüdős method to be rNIPAM = 0.83 and rDMA = 1.10. The thermoresponsive properties of these copo-lymers with varying molecular weights were characterized by visual turbidimetry and dynamic light scattering (DLS). The copolymers showed a lower critical solution temperature (LCST) in water with a dependence on the molar fraction of DMA in the copolymer. Chaotropic and kosmotropic salt anions of the Hofmeister series, known to affect the LCST of thermoresponsive polymers, were used as additives in the aqueous copolymer solutions and their influence on the LCST was demonstrated. Further on, in order to investigate the thermoresponsive behavior of P(DMA-co-NIPAM) in a confined state, P(DMA-co-NIPAM)-b-PS diblock copolymers were prepared via polymerization induced self-assembly (PISA) through surfactant-free RAFT mediated emulsion polymerization of styrene using P(DMA-co-NIPAM) as the macromolecular chain transfer agent (mCTA) of the polymerization. As confirmed by cryogenic transmission electron microscopy (cryoTEM), this approach yielded stabilized spherical micelles in aqueous dispersions where the PS block formed the hydrophobic core and the P(DMA-co-NIPAM) block formed the hydrophilic corona of the spherical micelle. The temperature-dependent behavior of the LCST-type diblock copolymers was further studied by examining the collapse of the P(DMA-co-NIPAM) minor block of the P(DMA-co-NIPAM)-b-PS diblock copolymers as a function of temperature in aqueous solution. The nanospheres were found to be thermosensitive by changing their hydrodynamic radii almost linearly as a function of temperature between 25 °C and 45 °C. The addition of kosmotropic salt anions, as a potentially useful tuning feature of micellar assemblies, was found to increase the hydrodynamic radius of the micelles and resulted in a faster collapse of the micelle corona upon heating.

scholarly journals Preparation and Properties of Thermoresponsive P(N-Isopropylacrylamide-co-butylacrylate) Hydrogel Materials for Smart Windows

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Jae-Hyung Park ◽  
Ji-Won Jang ◽  
Jae-Hak Sim ◽  
Il-Jin Kim ◽  
Dong-Jin Lee ◽  
...  
Keyword(s):  
Light Transmission ◽  
Crosslinking Agent ◽  
Three Dimensional ◽  
Light Transmittance ◽  
Solar Light ◽  
Solution Temperature ◽  
Smart Window ◽  
Thermoresponsive Polymers ◽  
Smart Windows ◽  
Hydrogel Films

Thermoresponsive polymers that exhibit phase transition in response to temperature change can be used as material for smart windows because they can control solar light transmission depending on the outside temperature. The development of thermoresponsive polymers for a smart window that can be used over a wide temperature range is required. Therefore, to obtain smart window materials that can be used at various temperatures, three-dimensional thermoresponsive P(NIPAm-co-BA) hydrogels were prepared by free radical polymerization from main monomer N-isopropylacrylamide, comonomer butyl acrylate, and crosslinking agent N,N′-methylenebisacrylamide (MBAm) in this study. This study examined the effect of BA content on the lower critical solution temperature (LCST) and the solar light transmittance of crosslinked P(NIPAm-co-BA) hydrogel films. The LCST of hydrogel films was found to be significantly decreased from 34.3 to 29.5°C with increasing BA content from 0 to 20 mol%. It was found that the transparent films at T=25°C (T<LCST) were converted to translucent films at a higher temperature (T=45°C) (T>LCST). These results suggested that the crosslinked P(NIPAm-co-BA) hydrogel materials prepared in this study could have high potential for application in smart window materials.

RAFT Graft Polymerization of 2-(Dimethylaminoethyl) Methacrylate onto Cellulose Fibre

2006 ◽  
Vol 59 (10) ◽  
pp. 737 ◽  
Author(s):  
Debashish Roy ◽  
James T. Guthrie ◽  
Sébastien Perrier
Keyword(s):  
Graft Polymerization ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Cellulose Fibre ◽  
Monomer Conversion ◽  
Living System ◽  
Degree Of Polymerization ◽  
Polymerization Time ◽  
Grafted Polymer ◽  
Reversible Addition

Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) was grafted from cellulose by reversible addition–fragmentation chain transfer (RAFT) polymerization. The use of a free chain transfer agent in solution allowed for a better control over graft ratio, chain length of grafted polymer, monomer conversion, and homopolymer formation in solution. An increase in polymerization time or degree of polymerization led to an increase in graft ratio, as expected from a living system.

Thermoresponsive polymers with lower critical solution temperature: from fundamental aspects and measuring techniques to recommended turbidimetry conditions

2017 ◽  
Vol 4 (2) ◽  
pp. 109-116 ◽  
Author(s):  
Qilu Zhang ◽  
Christine Weber ◽  
Ulrich S. Schubert ◽  
Richard Hoogenboom
Keyword(s):  
Lower Critical Solution Temperature ◽  
Temperature Behavior ◽  
Solution Temperature ◽  
Thermoresponsive Polymers ◽  
Critical Solution Temperature ◽  
Measuring Techniques

This focus article addresses fundamental and practical aspects of investigating polymers with lower critical solution temperature behavior.

Molecular Weight and Tacticity of Oligoacrylates by Capillary Electrophoresis - Mass Spectrometry

2010 ◽  
Vol 63 (8) ◽  
pp. 1219 ◽  
Author(s):  
Marianne Gaborieau ◽  
Tim J. Causon ◽  
Yohann Guillaneuf ◽  
Emily F. Hilder ◽  
Patrice Castignolles
Keyword(s):  
Capillary Electrophoresis ◽  
Raft Polymerization ◽  
Degree Of Polymerization ◽  
Size Exclusion ◽  
Separation Mechanism ◽  
Ionization Mass ◽  
Polymeric Particles ◽  
Reversible Addition ◽  
Exclusion Chromatography

Oligo(acrylic acid) efficiently stabilizes polymeric particles, especially particles produced by reversible addition–fragmentation chain transfer (RAFT) (as hydrophilic block of an amphiphilic copolymer). Capillary electrophoresis (CE) has a far higher resolution power to separate these oligomers than the commonly used size exclusion chromatography. Coupling CE to electrospray ionization mass spectrometric detection unravels the separation mechanism. CE separates these oligomers, not only according to their degree of polymerization, but also according to their tacticity, in agreement with NMR analysis. Such analysis will provide insight into the role of these oligomers as stabilizers in emulsion polymerization, and into the mechanism of the RAFT polymerization with respect to degree of polymerization and tacticity.

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