Totally Organic Redox-Active pH-Sensitive Nanoparticles Stabilized by Amphiphilic Aromatic Polyketones

Abstract

Amphiphilic aromatic polymers have been synthesized by grafting aliphatic polyketones with 4-(aminomethyl)benzoic acid at different molar ratios via the Paal-Knorr reaction. The resulting polymers, showing diketone conversion degree of 16%, 37%, 53%, and 69%, have been complexed with the redox-active 2,3,5-triphenyl-2H-tetrazolium chloride, a precursor molecule with which aromatic-aromatic interactions are held. Upon addition of ascorbic acid to the complexes, in situ reduction of the tetrazolium salt produced 1,3,5-triphenylformazan nanoparticles stabilized by the amphiphilic polymers. The stabilized nanoparticles display highly negative zeta potential [-(35-70) mV] and hydrodynamic diameters in the submicron range (100-400 nm). Nonaromatic polyelectrolytes or hydrophilic aromatic copolymers showing low linear aromatic density and high linear charge density such as acrylate/maleate and sulfonate/maleate-containing polymers were unable to stabilize formazan nanoparticles synthesized by the same method. The copolymers studied here bear uncharged nonaromatic comonomers (unreacted diketone units) as well as charged aromatic comonomers, which furnish amphiphilia. Thus, the linear aromatic density and the maximum linear charge density have the same value for each copolymer, and the hydrophilic/hydrophobic balance varies with the diketone conversion degree. The amphiphilia of the copolymers allows the stabilization of the nanoparticles, even with the copolymers showing a low linear aromatic density. The method of nanoparticle synthesis constitutes a simple, cheap, and green method for the production of switchable totally organic, redox-active, pH-sensitive nanoparticles that can be reversibly turned into macroprecipitates upon pH changing.

Porous polyelectrolyte materials with controlled luminescence properties based on aromatic‐aromatic interactions with rhodamine B

“…Aromatic‐aromatic interactions between aromatic polyelectrolytes (ArPEL) and complementary charged aromatic counterions (ArC) have been a field of study in our group for the last 15 years 1‐14 . In aqueous solution, these short‐ and medium‐range interactions are additional to long‐range electrostatic interactions and involve close contact between the interacting polymeric aromatic moieties and the ArC, producing ion pairs and the release of water from their respective hydration sphere.…”

Electrically-Conductive Polyketone Nanocomposites Based on Reduced Graphene Oxide

“…In addition, it may be also performed without solvent or in various organic solvents depending on the physical and chemical properties of the amine compound. It is tolerant to a number of primary amines making this easy synthesis a fast, cheap, and appealing approach to create polymers with almost any desired pendant functional group [31,32,35,36]. The resulting functional polymers find use in different applications such as self-healing materials [37,38], emulsions with adhesive properties [39,40], and coating materials [41].…”

pH-Responsive Polyketone/5,10,15,20-Tetrakis-(Sulfonatophenyl)Porphyrin Supramolecular Submicron Colloidal Structures

“…It is well known that these polymerization methods are cumbersome and expensive [ 37 ]. An alternative is represented by the chemical modification of alternating aliphatic polyketones with primary amine compounds via the Paal–Knorr reaction [ 38 , 39 , 40 , 41 , 42 , 43 , 44 ]. Throughout this method, hydrophilic/hydrophobic functional groups are grafted randomly on the polyketone backbone as pendant groups, producing random amphiphilic polymers [ 38 , 45 ].…”

“…An alternative is represented by the chemical modification of alternating aliphatic polyketones with primary amine compounds via the Paal–Knorr reaction [ 38 , 39 , 40 , 41 , 42 , 43 , 44 ]. Throughout this method, hydrophilic/hydrophobic functional groups are grafted randomly on the polyketone backbone as pendant groups, producing random amphiphilic polymers [ 38 , 45 ]. The Paal–Knorr reaction on polyketones shows appealing characteristics such as easiness and cheapness, solvent- and catalyst-free, quantitative yields, and water as the only by-product [ 46 , 47 ].…”

“…Besides, there are a myriad of commercially available primary amine compounds, allowing the chemical modification of polyketones with acid, basic, aromatic, and aliphatic groups [ 47 ]. The robustness opens the possibility of synthesizing smart polymers such as pH-responsive [ 38 ] and self-healing materials [ 39 , 40 ], emulsions with adhesive properties [ 46 , 48 ], and coatings [ 49 ].…”