The Experts below are selected from a list of 33966 Experts worldwide ranked by ideXlab platform

Richard Hoogenboom - One of the best experts on this subject based on the ideXlab platform.

  • redox controlled upper Critical Solution Temperature behaviour of a nitroxide containing polymer in alcohol water mixtures
    Polymer Chemistry, 2016
    Co-Authors: Olivier Bertrand, Richard Hoogenboom, Alexandru Vlad, Jean-françois Gohy
    Abstract:

    Research on stimuli responsive polymers builds momentum as nature-inspired applications using man-made materials are increasingly sought. Here, we show for the first time the thermo-responsive upper Critical Solution Temperature (UCST) behaviour of a nitroxide containing polymer based on (2,6,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO). It is demonstrated that poly(TEMPO methacrylate) (PTMA) exhibits a UCST-type cloud point Temperature in alcohol–water mixtures that can be tuned by external electrical stimuli. To exemplify this, we studied the UCST behaviour of this polymer in alcohol–water mixtures. The reversible redox response of PTMA is used to tune the thermo-responsive behaviour of the solvated polymer. The effect of the oxidation extent in PTMA on UCST is demonstrated and a correlation between the chemical and electrochemical oxidation routes is presented.

  • polymers with upper Critical Solution Temperature behavior in alcohol water solvent mixtures
    Progress in Polymer Science, 2015
    Co-Authors: Qilu Zhang, Richard Hoogenboom
    Abstract:

    Abstract Thermoresponsive polymers are of great importance in numerous nanotechnological and biomedical applications. Compared to polymers that undergo a lower Critical Solution Temperature (LCST) phase transition in aqueous Solution, i.e., demixing occurs upon heating, polymers exhibiting the reversed upper Critical Solution Temperature (UCST) behavior in aqueous Solution have been much less documented as it is more challenging to achieve this behavior in aqueous Solutions. Furthermore, the high sensitivity of UCST behavior to minor variation in polymer structure and Solution composition hampered the development of applications based on these polymers [18] . However, polymers with UCST transition in alcohol/water solvent mixtures are more commonly reported and exhibit promising properties for the preparation of ‘smart’ materials. This review will focus on the theory and development of such polymers with UCST behavior in alcohol/water solvent mixtures. By highlighting reported examples of UCST polymers in alcohol/water solvent mixtures, we aim to demonstrate the versatility and potential that such UCST polymers possess as biomedical and ‘smart’ materials.

  • Polymers with upper Critical Solution Temperature behavior in alcohol/water solvent mixtures
    Progress in Polymer Science, 2015
    Co-Authors: Qilu Zhang, Richard Hoogenboom
    Abstract:

    Thermoresponsive polymers are of great importance in numerous nanotechnological and biomedical applications. Compared to polymers that undergo a lower Critical Solution Temperature (LCST) phase transition in aqueous Solution, i.e., demixing occurs upon heating, polymers exhibiting the reversed upper Critical Solution Temperature (UCST) behavior in aqueous Solution have been much less documented as it is more challenging to achieve this behavior in aqueous Solutions. Furthermore, the high sensitivity of UCST behavior to minor variation in polymer structure and Solution composition hampered the development of applications based on these polymers [18]. However, polymers with UCST transition in alcohol/water solvent mixtures are more commonly reported and exhibit promising properties for the preparation of 'smart' materials. This review will focus on the theory and development of such polymers with UCST behavior in alcohol/water solvent mixtures. By highlighting reported examples of UCST polymers in alcohol/water solvent mixtures, we aim to demonstrate the versatility and potential that such UCST polymers possess as biomedical and 'smart' materials.

  • tuning the upper Critical Solution Temperature behavior of poly methyl methacrylate in aqueous ethanol by modification of an activated ester comonomer
    Polymer Chemistry, 2012
    Co-Authors: Qilu Zhang, Philipp Schattling, Patrick Theato, Richard Hoogenboom
    Abstract:

    A statistical copolymer of methyl methacrylate (MMA) and pentafluorophenyl methacrylate (PFPMA, 6 mol%) exhibits upper Critical Solution Temperature (UCST) behavior in aqueous ethanol Solutions tunable by post-polymerization modification with different amines. The phase transition behavior of the obtained copolymers in aqueous ethanol was evaluated in detail. As expected, all copolymers reveal an upper Critical Solution Temperature with 55 vol% or higher ethanol content. Furthermore, the solubility in aqueous ethanol of the copolymer can be increased by the introduction of hydrophilic moieties. When hydrophobic substituents are introduced a decrease in solubility was observed with low content of ethanol and an increase in solubility when adding more ethanol. As such, the thermoresponsive behavior of PMMA can be significantly altered by post-modification of 6 mol% of the reactive comonomer units. The hysteresis of the polymer phase transitions between heating and cooling was found to be strongly dependent on the polarity of the amine substituent and the ethanol/water ratio. The metastability of the hysteresis is addressed based on isothermal turbidity studies.

  • self assembly of poly 2 alkyl 2 oxazoline s by crystallization in ethanol water mixtures below the upper Critical Solution Temperature
    Macromolecular Rapid Communications, 2011
    Co-Authors: Christina Diehl, Richard Hoogenboom, Ina Dambowsky, Helmut Schlaad
    Abstract:

    Crystallization of poly(2-isobutyl-2-oxazoline) and poly(2-nonyl-2-oxazoline) is found to occur by room Temperature annealing below the upper Critical Solution Temperature in ethanol-water solvent mixtures. Both polymers produce similar self-assembled structures (see image), resembling the previously reported crystalline hierarchical structures obtained from hot aqueous poly(2-isopropyl-2-oxazoline) Solutions above the lower Critical Solution Temperature. These observations suggest that the crystallization induced self-assembly process is a rather general phenomenon occurring for semicrystalline polymers in liquid-liquid two phase systems.

Loren C. Wilson - One of the best experts on this subject based on the ideXlab platform.

  • mutual solubility and lower Critical Solution Temperature for water glycol ether systems
    Journal of Chemical & Engineering Data, 2005
    Co-Authors: Scott P. Christensen, Felipe A. Donate, Timothy C. Frank, And Randy J. Latulip, Loren C. Wilson
    Abstract:

    Mutual solubility and the lower Critical Solution Temperature (LCST) are reported for a number of water + ethylene glycol ether and water + propylene glycol ether systems near atmospheric pressure. For the systems studied, the LCST is in the range of −10 °C to 48 °C. Glycol ethers are unusual organic solvents in that they have both hydrophobic and hydrophilic functionality and can hydrogen bond with water. Because of this, their interactions with water are complex and difficult to predict. The presence of an LCST is characteristic of hydrogen-bonding mixtures, and the value of the LCST reflects the relative magnitude of hydrophobic/hydrophilic interactions in Solution. A higher LCST value is indicative of a glycol ether with greater hydrophilic character. For water + ethylene glycol ether mixtures, the glycol ether becomes increasingly hydrophilic (LCST increases) as the number of oxyalkylene repeating units increases. The opposite effect is seen for water + propylene glycol ether mixtures. In this case, ...

  • Mutual Solubility and Lower Critical Solution Temperature for Water + Glycol Ether Systems
    Journal of Chemical & Engineering Data, 2005
    Co-Authors: Scott P. Christensen, Felipe A. Donate, Timothy C. Frank, And Randy J. Latulip, Loren C. Wilson
    Abstract:

    Mutual solubility and the lower Critical Solution Temperature (LCST) are reported for a number of water + ethylene glycol ether and water + propylene glycol ether systems near atmospheric pressure. For the systems studied, the LCST is in the range of −10 °C to 48 °C. Glycol ethers are unusual organic solvents in that they have both hydrophobic and hydrophilic functionality and can hydrogen bond with water. Because of this, their interactions with water are complex and difficult to predict. The presence of an LCST is characteristic of hydrogen-bonding mixtures, and the value of the LCST reflects the relative magnitude of hydrophobic/hydrophilic interactions in Solution. A higher LCST value is indicative of a glycol ether with greater hydrophilic character. For water + ethylene glycol ether mixtures, the glycol ether becomes increasingly hydrophilic (LCST increases) as the number of oxyalkylene repeating units increases. The opposite effect is seen for water + propylene glycol ether mixtures. In this case, ...

Scott P. Christensen - One of the best experts on this subject based on the ideXlab platform.

  • mutual solubility and lower Critical Solution Temperature for water glycol ether systems
    Journal of Chemical & Engineering Data, 2005
    Co-Authors: Scott P. Christensen, Felipe A. Donate, Timothy C. Frank, And Randy J. Latulip, Loren C. Wilson
    Abstract:

    Mutual solubility and the lower Critical Solution Temperature (LCST) are reported for a number of water + ethylene glycol ether and water + propylene glycol ether systems near atmospheric pressure. For the systems studied, the LCST is in the range of −10 °C to 48 °C. Glycol ethers are unusual organic solvents in that they have both hydrophobic and hydrophilic functionality and can hydrogen bond with water. Because of this, their interactions with water are complex and difficult to predict. The presence of an LCST is characteristic of hydrogen-bonding mixtures, and the value of the LCST reflects the relative magnitude of hydrophobic/hydrophilic interactions in Solution. A higher LCST value is indicative of a glycol ether with greater hydrophilic character. For water + ethylene glycol ether mixtures, the glycol ether becomes increasingly hydrophilic (LCST increases) as the number of oxyalkylene repeating units increases. The opposite effect is seen for water + propylene glycol ether mixtures. In this case, ...

  • Mutual Solubility and Lower Critical Solution Temperature for Water + Glycol Ether Systems
    Journal of Chemical & Engineering Data, 2005
    Co-Authors: Scott P. Christensen, Felipe A. Donate, Timothy C. Frank, And Randy J. Latulip, Loren C. Wilson
    Abstract:

    Mutual solubility and the lower Critical Solution Temperature (LCST) are reported for a number of water + ethylene glycol ether and water + propylene glycol ether systems near atmospheric pressure. For the systems studied, the LCST is in the range of −10 °C to 48 °C. Glycol ethers are unusual organic solvents in that they have both hydrophobic and hydrophilic functionality and can hydrogen bond with water. Because of this, their interactions with water are complex and difficult to predict. The presence of an LCST is characteristic of hydrogen-bonding mixtures, and the value of the LCST reflects the relative magnitude of hydrophobic/hydrophilic interactions in Solution. A higher LCST value is indicative of a glycol ether with greater hydrophilic character. For water + ethylene glycol ether mixtures, the glycol ether becomes increasingly hydrophilic (LCST increases) as the number of oxyalkylene repeating units increases. The opposite effect is seen for water + propylene glycol ether mixtures. In this case, ...

Qilu Zhang - One of the best experts on this subject based on the ideXlab platform.

  • polymers with upper Critical Solution Temperature behavior in alcohol water solvent mixtures
    Progress in Polymer Science, 2015
    Co-Authors: Qilu Zhang, Richard Hoogenboom
    Abstract:

    Abstract Thermoresponsive polymers are of great importance in numerous nanotechnological and biomedical applications. Compared to polymers that undergo a lower Critical Solution Temperature (LCST) phase transition in aqueous Solution, i.e., demixing occurs upon heating, polymers exhibiting the reversed upper Critical Solution Temperature (UCST) behavior in aqueous Solution have been much less documented as it is more challenging to achieve this behavior in aqueous Solutions. Furthermore, the high sensitivity of UCST behavior to minor variation in polymer structure and Solution composition hampered the development of applications based on these polymers [18] . However, polymers with UCST transition in alcohol/water solvent mixtures are more commonly reported and exhibit promising properties for the preparation of ‘smart’ materials. This review will focus on the theory and development of such polymers with UCST behavior in alcohol/water solvent mixtures. By highlighting reported examples of UCST polymers in alcohol/water solvent mixtures, we aim to demonstrate the versatility and potential that such UCST polymers possess as biomedical and ‘smart’ materials.

  • Polymers with upper Critical Solution Temperature behavior in alcohol/water solvent mixtures
    Progress in Polymer Science, 2015
    Co-Authors: Qilu Zhang, Richard Hoogenboom
    Abstract:

    Thermoresponsive polymers are of great importance in numerous nanotechnological and biomedical applications. Compared to polymers that undergo a lower Critical Solution Temperature (LCST) phase transition in aqueous Solution, i.e., demixing occurs upon heating, polymers exhibiting the reversed upper Critical Solution Temperature (UCST) behavior in aqueous Solution have been much less documented as it is more challenging to achieve this behavior in aqueous Solutions. Furthermore, the high sensitivity of UCST behavior to minor variation in polymer structure and Solution composition hampered the development of applications based on these polymers [18]. However, polymers with UCST transition in alcohol/water solvent mixtures are more commonly reported and exhibit promising properties for the preparation of 'smart' materials. This review will focus on the theory and development of such polymers with UCST behavior in alcohol/water solvent mixtures. By highlighting reported examples of UCST polymers in alcohol/water solvent mixtures, we aim to demonstrate the versatility and potential that such UCST polymers possess as biomedical and 'smart' materials.

  • tuning the upper Critical Solution Temperature behavior of poly methyl methacrylate in aqueous ethanol by modification of an activated ester comonomer
    Polymer Chemistry, 2012
    Co-Authors: Qilu Zhang, Philipp Schattling, Patrick Theato, Richard Hoogenboom
    Abstract:

    A statistical copolymer of methyl methacrylate (MMA) and pentafluorophenyl methacrylate (PFPMA, 6 mol%) exhibits upper Critical Solution Temperature (UCST) behavior in aqueous ethanol Solutions tunable by post-polymerization modification with different amines. The phase transition behavior of the obtained copolymers in aqueous ethanol was evaluated in detail. As expected, all copolymers reveal an upper Critical Solution Temperature with 55 vol% or higher ethanol content. Furthermore, the solubility in aqueous ethanol of the copolymer can be increased by the introduction of hydrophilic moieties. When hydrophobic substituents are introduced a decrease in solubility was observed with low content of ethanol and an increase in solubility when adding more ethanol. As such, the thermoresponsive behavior of PMMA can be significantly altered by post-modification of 6 mol% of the reactive comonomer units. The hysteresis of the polymer phase transitions between heating and cooling was found to be strongly dependent on the polarity of the amine substituent and the ethanol/water ratio. The metastability of the hysteresis is addressed based on isothermal turbidity studies.

Seema Agarwal - One of the best experts on this subject based on the ideXlab platform.

  • polymers with upper Critical Solution Temperature in aqueous Solution unexpected properties from known building blocks
    ACS Macro Letters, 2013
    Co-Authors: Jan Seuring, Seema Agarwal
    Abstract:

    Polymers showing an upper Critical Solution Temperature (UCST) in aqueous Solution were not rare, but the UCST was rarely observed under practically relevant conditions. Recently, much progress has been made in the synthesis of polymer systems that display UCST behavior under mild and physiologic conditions. Current developments focus on polymers that rely on hydrogen bonding. This viewpoint explains the historical context, presents the major properties, and concludes with a discussion of the most recent examples.

  • Polymers with upper Critical Solution Temperature in aqueous Solution
    Macromolecular Rapid Communications, 2012
    Co-Authors: Jan Seuring, Seema Agarwal
    Abstract:

    This review focuses on polymers with upper Critical Solution Temperature (UCST) in water or electrolyte Solution and provides a detailed survey of the yet few existing examples. A guide for synthetic chemists for the design of novel UCST polymers is presented and possible handles to tune the phase transition Temperature, sharpness of transition, hysteresis, and effectiveness of phase separation are discussed. This review tries to answer the question why polymers with UCST remained largely underrepresented in academic as well as applied research and what requirements have to be fulfilled to make these polymers suitable for the development of smart materials with a positive thermoresponse.

  • Upper Critical Solution Temperature of Poly(N-acryloyl glycinamide) in Water: A Concealed Property
    Macromolecules, 2011
    Co-Authors: Jan Seuring, Frank M. Bayer, Klaus Huber, Seema Agarwal
    Abstract:

    Polymers showing an upper Critical Solution Temperature (UCST) in water are rare. Recently, the nonionic homopolymer poly(N-acryloyl glycinamide) (poly(NAGA)) has been shown to exhibit a sharp upper Critical Solution Temperature in pure water as well as in electrolyte Solution. Although poly(NAGA) is known for decades the UCST behavior had not been reported. The first controlled radical polymerization of poly(NAGA) by the RAFT (reversible addition–fragmentation transfer) process was also achieved recently, but no UCST was observed. The present study shows that traces of ionic groups in the polymer prevent phase separation. Failure to notice the UCST in the past was because ionic groups have been introduced unintentionally by either acrylate impurities in the monomer, hydrolysis of the polymer side chains, and/or usage of ionic initiators or chain transfer agents. A synthetic procedure for high purity NAGA monomer free of ionic impurities is reported. It is also shown how to obtain stable aqueous Solutions...