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International audience; A versatile and eco-compatible preparation route of functional ordered mesoporous materials will be described. It relies on the use of assemblies of hydrophilic diblock copolymers, in place of classical amphiphilic templates, as new structuring and functionalizing agents for the direct synthesis, at room temperature and in water, of polymer-functionalized mesoporous silica.The new structuring agents are dynamic PolyIon electrostatic Complex (PIC) micelles formed between double-hydrophilic-block-copolymers (DHBC) (constituted of a neutral block and an ionizable one) and an oppositely charged homopolyelectrolyte, which can be considered as an auxiliary of micellization of DHBC polymers.The different advantages of using PIC micelles are the following: due to their sensitivity to physicochemical parameters, PIC micelles allowed obtaining various hybrid mesostructures (cubic, 2D-hexagonal, lamellar...) by simply adjusting the material synthesis conditions using a unique DHBC/homopolyelectrolyte system. This is a consequence of the adjustable composition and water content of the polyion complex phase. The micellization process, which can be controlled by pH or ionic strength, is reversible in water and this allowed the recovery and recycling of the porogen polymers.Very interestingly, the use of PIC micelles permitted the direct preparation of polymer-functionalized mesopores. This was possible due to the easy dissociation of the polyion complex within the pores, selectively releasing the auxiliary of micellization while the DHBC remained for functionalizing the pores. This new method ensures an homogeneous functionalization of the mesopores, a control of the functional polymer chain lengths and a sufficient mesoporous volume. Moreover, the properties of the functional chains could be varied (acid, basic, metal-complexing...). Finally, this preparation route was extended to bio-functional hybrid mesophases useful as drug delivery systems [3] The direct formation of drug-loaded polymer-functionalized mesoporous materials was developed by using drug-polymer complex micelles as structuring agents ; this was shown with antibiotics exhibiting a pH-triggered release. Furthermore, studies are currently under way to estimate the catalytic performances of the new functional materials. more...

Polyion Complex (PIC) or Complex Coacervate Core (C3M) Micelles [1] have been used as structuring agents to template ordered mesostuctured porous silica materials [2]. PIC micelles assemble by electrostatic complexation of oppositely charged polyelectrolytes, one of them being a double hydrophilic block copolymer (DHBC). Compared to classical structuring agents obtained from amphiphilic molecules, PIC micelles offer several advantages: first, they can be recovered and reused in several mesoporous material synthesis cycles [2]. Secondly, they allow single step preparation of drug loaded porous materials [3]. Finally, tuning the characteristics of the porous material does no longer require the synthesis of new structuring agents: they can be adjusted by playing with the physico-chemical conditions, using a unique polyelectrolyte system. The present work aims at correlating the characteristics of the porous materials and the physico-chemical properties of the PIC micelles.Mesostructured materials have been prepared by condensation of TEOS in the presence of PIC micelles of polyethylene oxide-b-poly(acrylic acid) (POE-b-PAA) copolymer complexed with neomycin (NM) or oligochitosan (OC). TEM, sorption measurements and X-ray diffraction have shown that varying structures and pore sizes can be achieved by simply varying concentration and pH. On the other hand, using osmometry, specific ion potentiometry, elemental analysis and small angle X-ray scattering, the associative phase separation of poly(acrylic acid) in the presence of neomycin has been studied as a model system for the core of the PIC micelles.The hybrid materials obtained right after drying (without calcination) are porous. This is related to the high degree of swelling of the core of the PIC micelles that contains at least 50% of water in weight. The water content in the micelles varies with concentration because it is determined by osmotic equilibrium between the core and the suspending solution. This translates into variation of porous volume and allows fine tuning of the pore size in the hybrid material. These features are preserved after calcination. Finally, the pH of material synthesis has been shown to determine the drug loading: neomycin concentration in the hybrid porous material increases as pH increases.In conclusion, PIC micelles offer numerous advantages and opportunities in the domain of functional ordered mesostructured materials due to the sensitivity of their characteristics to physico-chemical parameters, allowing the reversibility of their assembling in water, the possible delivery of functional molecules and the possibility to control the swelling of PIC micelles core.References: [1] Voets, I. K.; de Keizer, A.; Stuart, M. A. C. Adv. Colloid Interface Sci., 2009, 147-48, 300-318.[2] Baccile, N.; Reboul, J.; Blanc, B.; Coq, B.; Lacroix-Desmazes, P.; In, M.; Gerardin, C. Angew. Chem. Int. Ed., 2008. 47(44), 8433-8437.[3] Molina, E.; Warnant, J.; Mathonnat, M.; Bathfield, M.; In, M.; Laurencin, D.; Jérôme, C.; Lacroix Desmazes, P.; Marcotte, N.; Gérardin, C. Langmuir, 2015. 31, 12839-12844. more...

Polyion Complex (PIC) or Complex Coacervate Core (C3M) Micelles [1] have been used as structuring agents to template ordered mesostuctured porous silica materials [2]. PIC micelles assemble by electrostatic complexation of oppositely charged polyelectrolytes, one of them being a double hydrophilic block copolymer (DHBC). Compared to classical structuring agents obtained from amphiphilic molecules, PIC micelles offer several advantages: first, they can be recovered and reused in several mesoporous material synthesis cycles [2]. Secondly, they allow single step preparation of drug loaded porous materials [3]. Finally, tuning the characteristics of the porous material does no longer require the synthesis of new structuring agents: they can be adjusted by playing with the physico-chemical conditions, using a unique polyelectrolyte system. The present work aims at correlating the characteristics of the porous materials and the physico-chemical properties of the PIC micelles.Mesostructured materials have been prepared by condensation of TEOS in the presence of PIC micelles of polyethylene oxide-b-poly(acrylic acid) (POE-b-PAA) copolymer complexed with neomycin (NM) or oligochitosan (OC). TEM, sorption measurements and X-ray diffraction have shown that varying structures and pore sizes can be achieved by simply varying concentration and pH. On the other hand, using osmometry, specific ion potentiometry, elemental analysis and small angle X-ray scattering, the associative phase separation of poly(acrylic acid) in the presence of neomycin has been studied as a model system for the core of the PIC micelles.The hybrid materials obtained right after drying (without calcination) are porous. This is related to the high degree of swelling of the core of the PIC micelles that contains at least 50% of water in weight. The water content in the micelles varies with concentration because it is determined by osmotic equilibrium between the core and the suspending solution. This translates into variation of porous volume and allows fine tuning of the pore size in the hybrid material. These features are preserved after calcination. Finally, the pH of material synthesis has been shown to determine the drug loading: neomycin concentration in the hybrid porous material increases as pH increases.In conclusion, PIC micelles offer numerous advantages and opportunities in the domain of functional ordered mesostructured materials due to the sensitivity of their characteristics to physico-chemical parameters, allowing the reversibility of their assembling in water, the possible delivery of functional molecules and the possibility to control the swelling of PIC micelles core.References: [1] Voets, I. K.; de Keizer, A.; Stuart, M. A. C. Adv. Colloid Interface Sci., 2009, 147-48, 300-318.[2] Baccile, N.; Reboul, J.; Blanc, B.; Coq, B.; Lacroix-Desmazes, P.; In, M.; Gerardin, C. Angew. Chem. Int. Ed., 2008. 47(44), 8433-8437.[3] Molina, E.; Warnant, J.; Mathonnat, M.; Bathfield, M.; In, M.; Laurencin, D.; Jérôme, C.; Lacroix Desmazes, P.; Marcotte, N.; Gérardin, C. Langmuir, 2015. 31, 12839-12844. more...