Click Chemistry in Materials Science Xi, Weixian; Scott, Timothy F.; Kloxin, Christopher J. ...
Advanced functional materials,
05/2014, Letnik:
24, Številka:
18
Journal Article
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Despite originating only a little more than a decade ago, click chemistry has become one of the most powerful paradigms in materials science, synthesis, and modification. By developing and ...implementing simple, robust chemistries that do not require difficult separations or harsh conditions, the ability to form, modify, and control the structure of materials on various length scales has become more broadly available to those in the materials science community. As such, click chemistry has seen broad implementation in polymer functionalization, surface modification, block copolymer and dendrimer synthesis, biomaterials fabrication, biofunctionalization, and in many other areas of materials science. Here, the basic reactions, approaches, and applications of click chemistry in materials science are highlighted, and a brief look is taken into the future enabling developments in this field.
Click chemistry has become one of the most powerful paradigms in materials science, synthesis and modification. This feature article delivers highlights of the basic reactions, approaches, and applications of click chemistry in materials science as well as briefly looking to the future, enabling developments in this field.
The key attribute of the thiol-Michael addition reaction that makes it a prized tool in materials science is its modular “click” nature, which allows for the implementation of this highly efficient, ...“green” reaction in applications that vary from small molecule synthesis to in situ polymer modifications in biological systems to the surface functionalization of material coatings. Over the past few decades, interest in the thiol-Michael addition reaction has increased dramatically, as is evidenced by the number of studies that have been dedicated to elucidating different aspects of the reaction that range from an in-depth analysis aimed at understanding the mechanistic pathways of the reaction to synthetic studies that have examined modifying molecular structures with the aim of yielding highly efficient thiol-Michael reaction monomers. This review examines the reaction mechanisms, the substrates and catalysts used in the reaction, and the subsequent implementation of the thiol-Michael reaction in materials science over the years, with particular emphasis on the recent developments in the arena over the past decade.
Implant related infections are the most common cause of joint arthroplasty failure, requiring revision surgeries and a new implant, resulting in a cost of $8.6 billion annually. To address this ...problem, we created a class of coating technology that is applied in the operating room, in a procedure that takes less than 10 min, and can incorporate any desired antibiotic. Our coating technology uses an in situ coupling reaction of branched poly(ethylene glycol) and poly(allyl mercaptan) (PEG-PAM) polymers to generate an amphiphilic polymeric coating. We show in vivo efficacy in preventing implant infection in both post-arthroplasty infection and post-spinal surgery infection mouse models. Our technology displays efficacy with or without systemic antibiotics, the standard of care. Our coating technology is applied in a clinically relevant time frame, does not require modification of implant manufacturing process, and does not change the implant shelf life.
Nucleobase interactions play a fundamental role in biological functions, including transcription and translation. Natural nucleic acids like DNA are also widely implemented in material realm such as ...DNA guided self-assembly of nanomaterials. Inspired by that, polymer chemists have contributed phenomenal endeavors to mimic both the structures and functions of natural nucleic acids in synthetic polymers. Similar sequence-dependent responses were observed and employed in the self-assembly of these nucleobase-containing polymers. Here, the structures, synthetic approaches, and applications of nucleobase-containing polymers are highlighted and a brief look is taken at the future development of these polymers.
Photochemical processes enable spatial and temporal control of reactions, which can be implemented as an accurate external control approach in both polymer synthesis and materials applications. ...“Click” reactions have also been employed as efficient tools in the same field. Herein, we combined photochemical processes and thiol-Michael “click” reactions to achieve a “photo-click” reaction that can be used in surface patterning and controlled polymer network formation, owing to the ease of spatial and temporal control through use of photolabile amines as appropriate catalysts.
Synthetic polymer approaches generally lack the ability to control the primary sequence, with sequence control referred to as the holy grail. Two click chemistry reactions were now combined to form ...nucleobase‐containing sequence‐controlled polymers in simple polymerization reactions. Two distinct approaches are used to form these click nucleic acid (CNA) polymers. These approaches employ thiol–ene and thiol‐Michael reactions to form homopolymers of a single nucleobase (e.g., poly(A)n) or homopolymers of specific repeating nucleobase sequences (e.g., poly(ATC)n). Furthermore, the incorporation of monofunctional thiol‐terminated polymers into the polymerization system enables the preparation of multiblock copolymers in a single reaction vessel; the length of the diblock copolymer can be tuned by the stoichiometric ratio and/or the monomer functionality. These polymers are also used for organogel formation where complementary CNA‐based polymers form reversible crosslinks.
Click by click: The utilization of orthogonal thiol‐X click reactions provides a method for sequence‐controlled polymer synthesis. When combined with functional side groups in general and nucleobases in particular, this approach enables the formation of novel, highly functionalized materials in a robust, simple, and scalable manner (Trt=trityl).
Polymers that possess dynamic covalent bonds activated at ambient conditions are ideal platforms for smart, responsive materials. Herein, a class of dynamic covalent polymerizations is developed ...based on the thiol-thioester exchange, that is, transthioesterification, reaction. Shifts in the equilibrium extent of the exchange reactions are deliberately utilized to drive the formation of oligomers and polymers. In particular, a series of AB and A2-B2 monomers, including amino acid derivatives, were polymerized rapidly by catalytic amounts of mild bases in various organic solvents under ambient conditions. Thioester backbone oligopeptides, including cysteine and glycine, were obtained with an average repeating unit of four and a PDI of 1.8. Further, structurally dynamic hydrogels were obtained by such reactions between four-armed poly(ethylene glycol)-10000 based monomers in neutral water. These hydrogels showed dynamic, frequency-dependent flow behavior between sol and gel states.
We report a dispersion polymerization method based on thiol–Michael addition reactions for the preparation of cross-linked, narrow dispersity microparticles with well-defined, tunable physicochemical ...properties. Polymerization between pentaerythritol tetra(3-mercaptopropionate) (PETMP) and trimethylolpropane triacrylate in methanol was chosen as a model system, with the addition of triethylamine as a catalyst and polyvinylpyrrolidone as a stabilizer. The formation of microparticles took place within seconds at ambient conditions, as a result of a polymerization driven phase transition from dissolved monomers to precipitated polymers. The particle size was found to be affected by the amount of catalyst, the monomer concentration, and the monomer/polymer solubility in the reaction media. Monodispersity was achieved within a range of particle diameters from 1.6 to 4.3 μm, as determined both by scanning electron microscopy and dynamic light scattering. The reaction kinetics were studied by Fourier transform infrared spectroscopy by analyzing aliquots withdrawn from the reaction system at various reaction time points. Nearly quantitative conversions were achieved within 6 h for stoichiometric systems and 1 h for off-stoichiometric systems, both initiated with triethylamine. By utilizing photolabile bases as the reaction catalyst, phototriggered formation of the microparticles was demonstrated with ultraviolet irradiation. Monodisperse particles were formed with hexylamine and 1,1,3,3-tetramethylguanidine, both with 2-(2-nitrophenyl)propyloxycarbonyl as the UV-labile photocage. Furthermore, as a demonstration of the versatility of this method, microparticles were prepared from copolymerizations between PETMP and four types of diacrylates with varied backbone structures. With increased backbone rigidity, the microparticle glass transition temperature increased from −36 to 8 °C. This method provides a platform for the realization of the nearly ideal step-growth networks in microscale, with highly tunable backbone structures, robust thermal transitions, and intrinsic functionalization capacity.
Orthogonal, sequential “click” reactions were implemented to yield novel polymeric substrates with the ability to record holographic data. The base-catalyzed thiol–acrylate Michael “click” reaction ...was implemented to yield a writable, stage 1 polymeric substrate with glass transition temperatures (T g) ranging from 0 to −26 °C and rubbery storage moduli (E′) from 11.1 to 0.3 MPa. The loosely cross-linked matrix also contained a novel high refractive index monomer 9-(2,3-bis(allyloxy)propyl)-9H-carbazole (BAPC) that did not participate in the thiol–Michael reaction but allowed for large index gradients to be developed within the network upon subsequent exposure to coherent laser beams and initiation of the radical-mediated thiol–ene reaction. The holographic gratings were recorded with 96% diffraction efficiency and ca. 2.4 cm/mJ of light sensitivity in 2 s under a 405 nm exposure with an intensity of 20 mW/cm2. Subsequent to pattern formation, via a thiol–allyl radical “click” photopolymerization initiated by flood illumination of the sample, holographic materials with high T g, high modulus, diffraction efficiency as high as 82%, and refractive index modulation of 0.004 were obtained. Graded rainbow holograms that displayed colors from blue to red at a single viewing angle were readily formed through this new technique.
Low surface energy materials have attracted much attention due to their properties and various applications. In this work, we synthesized and characterized a series of ultraviolet (UV)-curable ...fluorinated siloxane polymers with various fluorinated acrylates-hexafluorobutyl acrylate, dodecafluoroheptyl acrylate, and trifluorooctyl methacrylate-grafted onto a hydrogen-containing poly(dimethylsiloxane) backbone. The structures of the fluorinated siloxane polymers were measured and confirmed by proton nuclear magnetic resonance and Fourier transform infrared spectroscopy. Then the polymers were used as surface modifiers of UV-curable commercial polyurethane (DR-U356) at different concentrations (1, 2, 3, 4, 5, and 10 wt %). Among three formulations of these fluorinated siloxane polymers modified with DR-U356, hydrophobic states (91°, 92°, and 98°) were obtained at low concentrations (1 wt %). The DR-U356 resin is only in the hydrophilic state at 59.41°. The fluorine and siloxane element contents were investigated by X-ray photoelectron spectroscopy and the results indicated that the fluorinated and siloxane elements were liable to migrate to the surface of resins. The results of the friction recovering assays showed that the recorded contact angles of the series of fluorinated siloxane resins were higher than the original values after the friction-annealing progressing.
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