Incorporation of poly(acrylic acid), poly(vinylsulfonate) and poly(styrenesulfonate) within layered double hydroxides

Abstract

Poly(acry1ic acid), poly(vinylsu1fonate) and poly(styrenesu1fonate) have been incorporated between the positively charged sheets of layered double hydroxides (LDHs) M1 -xA1,(OH)2f (M = Mg, Ca, Co) and Zn,-,M',(OH),+ (M'= Al, Cr) to form layered nanocomposites. The resulting nanocomposites contained the LDH sheet structures separated by 7.6-16.0 A, which is sufficient to accommodate polymer bilayers between the LDH sheets. Preparations were carried out in deaerated aqueous base by a template reaction, involving the formation and precipitation of nanocomposites from metal nitrate-salt precursors in the presence of the dissolved polymer. Structural and compositional details were provided by X-ray diffraction (XRD), FTIR spectroscopy, elemental analysis, differential scanning calorimetry (DSC) and thermogravimetry (TG). Scanning electron microscopy (SEM) indicates that the nanocomposition of LDHs with ionomers significantly alters the particle microstructure from that of the LDH carbonates derived from aqueous precipitation.The layered double hydroxides (LDHs), otherwise called 'anionic clays', and their intercalation compounds have received considerable attention in recent years in view of their potential technological importance as catalysts, ion exchangers, optical hosts, ceramic precursors and antacids.'-'' The LDH structure consists of brucite-like M(OH), sheets, where partial substitution of trivalent for divalent cations results in a positive sheet charge compensated by anions within interlayer galleries. LDHs are represented by the general formula [M111-xM111'x(OH)2]Xt *[(An"-),,,,, -nH,O] with representative examples M = Mg, Zn or Ca; M' = Al, Cr or Fe; An"-=C032-, C1-, OH-, NO3or SO4'-, and x taking values between 0.16 and 0.45.'' Thus, the mineral hydrotalcite can be abbreviated as Mg-A1-C03-LDH with x=O.25, and has the approximate formula unit Paper 5/04853B;

Formation of an Inorganic‐Organic Host‐Guest Material by Intercalation of Acetone Formaldehyde Sulfite Polycondensate into a Hydrocalumite Structure

“…Similar d values were reported for organic sulfonated compounds such as e.g. poly(vinyl sulfonate) and poly(styrene sulfonate) [12] and alkyl sulfonates [13]. There, basal spacings in the range of 13.2 Å -19.6 Å and 27.0 Å -32.3 Å, respectively were found.…”

Síntese de nanocompósitos com propriedades anisotrópicas via polimerização radicalar controlada em emulsão

“…50 Fulvic, humic and acrylic acids, however, seem to have been successfully intercalated into Montmorillonite at low pH (lower than 4). Ramos-Tejeda and coworkers 52 studied the effect of humic acid (HA) in flow properties of Mt dispersions, finding a significantly high adsorption of HA onto the platelets, as previously verified by Tombácz et al 53 .…”

“…These issues were later attributed to the partitioning of the RAFT agent, that cannot be properly transported between aqueous phase, monomer droplets and the polymerizing particles and to the superswelling effect of the polymer particles. [48][49][50][51][52][53][54] In 2002, 55 a new method has been described for the effective ab initio RAFT emulsion polymerization. In this novel strategy, hydrophilic RAFT agents that contain short stabilizing segments of hydrophilic monomers were used in the emulsion polymerization of hydrophobic monomers to form amphipathic species that self-assemble to form micelles.…”

“…Indeed, the control of some factors, such as the ionic strength and the pH of the solution, may favor adsorption, contrary to the expectation that the negatively charged polymers are repelled by the negative charges of the clay surface. 50 The variations in the pH are responsible for changing the ionization and chain conformation of the polyanions, as well as the edge charges of the clay platelets and, in general, adsorption of polyanions increases with decreasing the pH. 51 Some works based on X-ray diffractions indicate that, contrary to cationic and nonionic polymers, polyanions in general do not penetrate the galleries of 2:1 phyllosilicates.…”

“…In the template synthesis (sol-gel technology) technique, the clay minerals are synthesized in the presence of an aqueous solution of the polymer matrix. This method is widely used for the synthesis of nanocomposites based on layered double hydroxides [50][51][52] however, some disadvantages of the technique must be considered for layered silicates. The high temperature required to synthesize most clay minerals may cause the decomposition of the polymer matrix.…”