Synthetically structured water-soluble copolymers

The use of double hydrophilic block copolymers in biomimetic mineralization processes has been investigated in recent years. In contrast to rigid templates (like carbon nanotubes and porous aluminum templates which predefine the final structure) water soluble polymers could be used as soluble species at various hierarchy levels. Usually, in the case of DHBCs, one of the block acts as scaffold for the development of the crystal, while the other acts as a soluble-stabilizing matrix. Therefore, both of the blocks play a crucial role on the development of the crystals. There is a plethora of reports on the emerging bio-inspired mineralization field. Various crystal structures have been presented during the last years, following versatile synthetic routes. A very detailed and illustrious review has been recently given by Colfen [3]. The above review describes in detail all aspects of the specific field. Herein, we present just a few selected examples. 

The nature of hydrophobic interactions and their effects on the structure and properties of water have been extensively studied, particularly for small molecules (i 3). In contrast, the introduction of hydrophobic associations into synthetic water-soluble polymers to control solution rheology has received rather limited and recent study (4-7). To better understand the relationships between polymer structure and solution properties, we have synthesized and characterized a series of copolymers of acrylamide and N-substituted alkylacrylamides and terpolymers containing anionically charged carboxyl groups. Solution properties of these systems have been obtained in both the dilute and semidilute concentration regime, to probe the influence of intra- and intermolecular interactions. In addition, the influence of the shear field and solvent quality on the associations was studied. 

Polyvinylpyrrolidone (PVP) (monomer-unit structure [I]) is a water-soluble synthetic polymer v ich is stable physically and ch ically in aqueous solution (1-3), and which is commercially available in a diversity of molecular weight grades (4). From these features alone, PVP has potential for use in oil-recovery and related applications similarly, its monomer unit has potential as a component of copolymers tailored for these applications (5). In any such applications, it is important not only that the polymer remains in solution under all conditions of teirperature, pressure and salinity that may be encountered, but that its solutions also retain the desired rheological behavior. Ensuring that this happens, especially with novel copolymers, requires that we have a good understandirq of the molecular interactions which occur in these aqueous polymer systems. 

This assembly chemistry is only limited by the preparation of an appropriate amphiphilic or hydrophobic diblock copolymer. With the structure and chemical composition of the resultant nanoparticles readily tunable using a wide range of block copolymers that are synthetically available. A broad range of polymers have been utilized as the core hydrophobic domain of shell-crosslinked nanoparticles and include styrene, isoprene, butadiene, caprolactone, poly (ethylene oxide), acrylates, methacrylate and acrylamides. Monomers that have been used to prepare the hydrophilic water-soluble domain include, among others, poly(ethylene glycol), acrylic acid, 4-vinylpyridine, (meth)acrylic acid, 2-dimethylaminoethyl methacrylate and Wisopropylacrylamide. 

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