Periodic Reporting for period 2 - BINAMA (Biomimicking nanostructured materials via intra(inter)molecular folding of sequence-controlled polymers)
Período documentado: 2018-07-20 hasta 2019-07-19
-The project sought to enable the synthesis of functional polymers where the sequence of each block can be controlled. To achieve this we first developed a universal polymerization protocol that can simultaneously polymerize monomers from different families including acrylates, methacrylates and styrene (J. Am. Chem. Soc., 2017, 139, 1003–1010). I then focused on the polymerization of a wide range of semi-fluorinated monomers that can be potentially used as MRI contrast agents. This polymerization was induced through the use of light as an external stimuli. Ultimately, I managed to synthesize sequence-controlled polymers consisting of hydrophilic, hydrophobic and semi-fluorinated moieties with good molecular characteristics, high monomer conversions and exceptional end-group fidelity. Such materials can find use in a range of applications such as self-assembly in bulk and in solution and folding of polymer chains to mimic proteins. The action concluded that the synthesis of complex sequence-controlled polymers is now possible and further investigation into the scope and applications of such materials is currently under investigation.
-Project 1: Universal Conditions for the Controlled Polymerization of Acrylates, Methacrylates, and Styrene via Cu(0)-RDRP
Main results achieved: Atom transfer radical polymerization (ATRP) typically requires various parameters to be optimized in order to achieve a high degree of control over molecular weight and dispersity (such as the type of initiator, transition metal, ligand, solvent, temperature, deactivator, added salts, and reducing agents). These components play a major role when switching monomers, e.g. from acrylic to methacrylic and/or styrenic monomers during the synthesis of homo- and block copolymers as the stability and reactivity of the carbon centered propagating radical dramatically changes. This is a challenge for both “experts” and nonexperts as choosing the appropriate conditions for successful polymerization can be time-consuming and overall an arduous task. During my Marie Curie Fellowship I worked with a PhD student and figured out one set of universal conditions for the efficacious polymerization of acrylates, methacrylates and styrene (using an identical initiator, ligand, copper salt, and solvent) based on commercially available and inexpensive reagents (PMDETA, IPA, Cu(0) wire). The versatility of these conditions is demonstrated by the near quantitative polymerization of these monomer families to yield well-defined materials over a range of molecular weights with low dispersities (∼1.1–1.2). The control and high end group fidelity is further exemplified by in situ block copolymerization upon sequential monomer addition for the case of methacrylates and styrene furnishing higher molecular weight copolymers with minimal termination. The facile nature of these conditions, combined with readily available reagents, will greatly expand the access and availability of tailored polymeric materials to all researchers.
Exploitation and dissemination: This work was published in one of the best chemistry journals (Journal of the American Chemical Society, 2017, 139 (2), 1003-1010) and was presented in the at the APME polymer conference at Ghent, Belgium where I was an invited speaker.
-Project 2: Light-mediated atom transfer radical polymerization of semi-fluorinated (meth) acrylates: facile access to functional materials
Main results achieved:
I worked closely with a PhD student to develop a highly efficient photomediated atom transfer radical polymerization protocol for semi-fluorinated acrylates and methacrylates. Use of the commercially available solvent, 2-trifluoromethyl-2-propanol, optimally balances monomer, polymer, and catalyst solubility while eliminating transesterification as a detrimental side reaction. In the presence of UV irradiation and ppm concentrations of copper(II) bromide and Me6-TREN (TREN = tris(2-aminoethyl amine)), semi-fluorinated monomers with side chains containing between three and 21 fluorine atoms readily polymerize under controlled conditions. The resulting polymers exhibit narrow molar mass distributions (Đ ≈ 1.1) and high end group fidelity, even at conversions greater than 95%. This level of control permits the in situ generation of chain-end functional homopolymers and diblock copolymers, providing facile access to semi-fluorinated macromolecules using a single methodology with unprecedented monomer scope. These results should create opportunities across a variety of fields that exploit fluorine-containing polymers for tailored bulk, interfacial, and solution properties.
Exploitation and dissemination: This work was published in one of the best chemistry journals (Journal of the American Chemical Society, 2017, 139 (16), 5939-5945) and was presented in the Gordon Polymer Conference and the APME polymer conference at Ghent, Belgium.
-Project 3: One‐Pot Synthesis of ABCDE Multiblock Copolymers with Hydrophobic, Hydrophilic, and Semi‐Fluorinated Segments
Main results achieved: Very few synthetic methodologies enable the preparation of arbitrary multiblock copolymer sequences comprising disparate functionality (e.g. hydrophobic, hydrophilic and fluorinated). Challenges broadly include polymerization difficulties (solubility, reactivity, control) and/or laborious procedures involving isolation, purification and re-initiation after each block growth. Through this Marie Curie Fellowship I managed to demonstrate the scope and accessibility of sequence-controlled multiblock copolymers by direct “in-situ” polymerization of hydrophobic, hydrophilic and fluorinated monomers. Key to this strategy was the ability to synthesize ABCDE, EDCBA and EDCBABCDE sequences with high monomer conversions (>98 %) through iterative monomer additions, yielding excellent block purity and low overall molar mass dispersities (Ð<1.16). This was achieved by optimizing the solvent (trifluoroethanol was found to be an optimal solvent which could maintain high end group fidelity and also good solubility of all reagents) as well as the ratio between copper and ligand. The materials were characterized by NMR, mass-spec and GPC analysis.
Exploitation and dissemination: This work was published in one of the best chemistry journals (Angew. Chem. Int. Ed, 2018, 56, 14483–14487) and was presented in the Gordon Polymer Conference.
Main results achieved: Atom transfer radical polymerization (ATRP) typically requires various parameters to be optimized in order to achieve a high degree of control over molecular weight and dispersity (such as the type of initiator, transition metal, ligand, solvent, temperature, deactivator, added salts, and reducing agents). These components play a major role when switching monomers, e.g. from acrylic to methacrylic and/or styrenic monomers during the synthesis of homo- and block copolymers as the stability and reactivity of the carbon centered propagating radical dramatically changes. This is a challenge for both “experts” and nonexperts as choosing the appropriate conditions for successful polymerization can be time-consuming and overall an arduous task. During my Marie Curie Fellowship I worked with a PhD student and figured out one set of universal conditions for the efficacious polymerization of acrylates, methacrylates and styrene (using an identical initiator, ligand, copper salt, and solvent) based on commercially available and inexpensive reagents (PMDETA, IPA, Cu(0) wire). The versatility of these conditions is demonstrated by the near quantitative polymerization of these monomer families to yield well-defined materials over a range of molecular weights with low dispersities (∼1.1–1.2). The control and high end group fidelity is further exemplified by in situ block copolymerization upon sequential monomer addition for the case of methacrylates and styrene furnishing higher molecular weight copolymers with minimal termination. The facile nature of these conditions, combined with readily available reagents, will greatly expand the access and availability of tailored polymeric materials to all researchers.
Exploitation and dissemination: This work was published in one of the best chemistry journals (Journal of the American Chemical Society, 2017, 139 (2), 1003-1010) and was presented in the at the APME polymer conference at Ghent, Belgium where I was an invited speaker.
-Project 2: Light-mediated atom transfer radical polymerization of semi-fluorinated (meth) acrylates: facile access to functional materials
Main results achieved:
I worked closely with a PhD student to develop a highly efficient photomediated atom transfer radical polymerization protocol for semi-fluorinated acrylates and methacrylates. Use of the commercially available solvent, 2-trifluoromethyl-2-propanol, optimally balances monomer, polymer, and catalyst solubility while eliminating transesterification as a detrimental side reaction. In the presence of UV irradiation and ppm concentrations of copper(II) bromide and Me6-TREN (TREN = tris(2-aminoethyl amine)), semi-fluorinated monomers with side chains containing between three and 21 fluorine atoms readily polymerize under controlled conditions. The resulting polymers exhibit narrow molar mass distributions (Đ ≈ 1.1) and high end group fidelity, even at conversions greater than 95%. This level of control permits the in situ generation of chain-end functional homopolymers and diblock copolymers, providing facile access to semi-fluorinated macromolecules using a single methodology with unprecedented monomer scope. These results should create opportunities across a variety of fields that exploit fluorine-containing polymers for tailored bulk, interfacial, and solution properties.
Exploitation and dissemination: This work was published in one of the best chemistry journals (Journal of the American Chemical Society, 2017, 139 (16), 5939-5945) and was presented in the Gordon Polymer Conference and the APME polymer conference at Ghent, Belgium.
-Project 3: One‐Pot Synthesis of ABCDE Multiblock Copolymers with Hydrophobic, Hydrophilic, and Semi‐Fluorinated Segments
Main results achieved: Very few synthetic methodologies enable the preparation of arbitrary multiblock copolymer sequences comprising disparate functionality (e.g. hydrophobic, hydrophilic and fluorinated). Challenges broadly include polymerization difficulties (solubility, reactivity, control) and/or laborious procedures involving isolation, purification and re-initiation after each block growth. Through this Marie Curie Fellowship I managed to demonstrate the scope and accessibility of sequence-controlled multiblock copolymers by direct “in-situ” polymerization of hydrophobic, hydrophilic and fluorinated monomers. Key to this strategy was the ability to synthesize ABCDE, EDCBA and EDCBABCDE sequences with high monomer conversions (>98 %) through iterative monomer additions, yielding excellent block purity and low overall molar mass dispersities (Ð<1.16). This was achieved by optimizing the solvent (trifluoroethanol was found to be an optimal solvent which could maintain high end group fidelity and also good solubility of all reagents) as well as the ratio between copper and ligand. The materials were characterized by NMR, mass-spec and GPC analysis.
Exploitation and dissemination: This work was published in one of the best chemistry journals (Angew. Chem. Int. Ed, 2018, 56, 14483–14487) and was presented in the Gordon Polymer Conference.
Thanks to this fellowship I have published many peer-reviewed articles in which I have revolutionized the field of controlled radical polymerization allowing rapid access to the synthesis of complex materials. For example, through the development of universal conditions that can be used to control the polymerization of many different monomer types, various materials can be targeted and our system can be used by both experts and non-experts thus bridging different fields. Although the nature of this Marie Curie project is by nature conducting fundamental polymer chemistry, the outcomes can improve the way current polymerizations are run and simplify current polymerization protocols ultimately leading to cheaper and better defined polymeric materials. In addition, the simplicity of the methods developed allows for this research to be used in undergraduate laboratories thus contributing to the enhancement of the education system of Europe.