In this work, Zn/Al layered double hydroxides intercalated with dodecyl sulfate ion (DS) in molar ratios (Zn2+/Al3+) 2:1, 3:1 and 4:1 were synthesized by co-precipitation method and then they were adsolubilized with essential oil of copaiba in the concentrations of 3, 5, 10, 13 and 15% wt/wt to be used as carriers in therapeutic ointments for skin injury treatments. The XRD results showed a diffraction pattern corresponding to the structure of LDHs with the presence of diffraction peaks referring to the basal reflection planes. Typical stretching and vibration bands of copaiba essential oil in FTIR spectra confirmed the adsolubilization process. The oil release plateau in the ointment was above 80% at normalized values in a time of approximately 20 h, the time required for dissolution and release of molecules adsorbed in the layered structure of the material for molar ratios 2:1 and 3:1 and the release of the solubilized molecules in the interlayer space. In contrast, LDH with a 4:1 molar ratio showed slower release and did not reach the plateau in 48 h, as this material has the ability to retain oil molecules in the LDH for longer, causing a slower release in relation to other molar ratios. The analysis for the non-intercalated copaiba oil showed a gradual increase in the concentration of the oil in the ointment, indicating a different curve profile.

Abstract Hydrotalcite-type materials, or layered double hydroxide (LDH), are very promising in applying slow-release drug systems through ion exchange and delamination characteristics at acidic pH. In this paper, Zn/Al LDHs in 2:1 and 3:1 molar ratios intercalated with the drug ibuprofen (IBU) were added to chitosan/alginate membranes. In the release tests, an increase in the solubility of the drug in the membranes could be observed, and the percentage of drug release is lower than the percentage of drug release in the free samples. The following release percentages were obtained: 15.48% and 17.5% of the drug in water, and 23.22% and 26.25% of the drug in PBS buffer solution, respectively, for membrane samples containing Zn2Al-IBU and Zn3Al-IBU LDHs. Thus, the synthesized hybrid membranes (chitosan/alginate-LDH-IBU) are promising in the application as resorbable membranes for bone grafting with drug release.

Abstract Cobalt/aluminum and nickel/aluminum layered double hydroxide (LDH - M+2:Al molar ratio of 3:1) were intercalated with dodecylsulphate (DDS), laurate (LAU), stearate (STE) and palmitate (PAL) and used as filler in low-density polyethylene (LDPE) in percentages between 0.2 and 7.0wt%. After injection molding, the samples were submitted to morphological characterization by scanning electron microscopy (SEM), analysis of thermal behavior by differential scanning calorimetry (DSC) and investigation of rheological properties. All Co/Al-LDPE samples showed the formation of a high temperature polymer crystal domain, induced by the LDH filler. The rheological properties indicated in general a reduction of shear modulus due to incompatibility between some regions of LDH and LDPE, which promoted phase separation. However, interaction with the LDH surface indicated higher affinity of the Ni/Al-LDH for the LDPE compared to Co/Al-LDH, forming permanent networks.

Green (Ni2+/Al+3) and pink (Co2+/Al+3) layered double hydroxides (LDH) (molar ratio of 3:1) were intercalated with several organic anions and used as functional colored fillers into low density polyethylene (LDPE) by melt mixing in amounts of 0.2 to 7 wt.%. Scanning electron microscopic (SEM) results of LDPE nanocomposites indicated that with low percentage of filler, all the LDH samples showed efficient delamination/exfoliation in the polymer matrix. Fillers added to LDPE with concentrations of 0.2, 0.5, 2 and 5% presented, in general, maintenance of Young's modulus and tensile strength, tending to the reduction with a loading of 7%. Most of the nanocomposites presented similar elongations, although NiUS stood out, with an elongation increase of 300%. Differential scanning calorimetry (DSC) indicated the effect of the Co/Al-LDH in inducing the formation of LDPE crystalline domains, especially at higher temperature than neat LDPE.

Resumo De forma a mimetizar o pigmento Azul Maya, dois corantes azo (alaranjado de metila - AM e vermelho congo - VC) foram inseridos na estrutura porosa da paligorsquita. Os materiais híbridos foram caracterizados por difração de raios X, espectroscopia de energia dispersiva, microscopia eletrônica de varredura, espectroscopia na região do ultravioleta-visível e análise superficial (área superficial por BET, tamanho e volume de poros por BJH). Após dispersar os materiais híbridos no poli(álcool vinílico), filmes coloridos e transparentes foram obtidos por casting úmido. Após acondicionamento em uma dessecador por uma semana a uma umidade controlada de 43 ± 2% os filmes foram avaliados em relação as suas propriedades mecânicas. De modo geral, o material PVA-PGS/AM teve um aumento no módulo de Young, tensão de ruptura e redução do alongamento enquanto que a paligorsquita bruta e PVA-PGS/VC apresentaram um comportamento oposto.

Abstract To mimic the Maya Blue pigment, two azo dyes (methylorange - AM and congo red - VC) were inserted into the porous structure of paligorskite. The hybrid materials were characterized by X-ray diffraction, energy dispersive spectroscopy, scanning electron microscopy, UV-Vis spectroscopy and surface analysis (surface area by BET, pore size and volume by and BJH). After dispersing the hybrid materials into poly(vinyl alcohol), colored and transparent films were obtained by wet casting. After conditioned into desiccators at controlled humidity of 43 ± 2% for one week, the films were evaluated in relation to their mechanical properties. In general, the material PVA-PGS/AM increases Young’s modulus and ultimate tensile strength reducing the elongation while raw paligorskite and PVA-PGS/VC presented an opposite behavior.

In this study, polymer composites using low-density polyethylene (LDPE) and layered hydroxide salts (LHS) were synthesized. The following compositions of LHS were obtained Zn5(OH)8(An-)2/n.yH2O, where A was varied in order to obtain hydrophilic (A = NO3-) or hydrophobic (A = DDS- - dodecyl sulfate or DBS- - dodecyl benzene sulfonate). Synthesis was carried out by co-precipitation in alkaline medium and drying, being followed by characterization via Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy. A variable amount of filler was then incorporated into the LDPE via extrusion, which was then injection molded to obtain specimens for evaluating tensile properties (Young's modulus, tensile strength, strain at break and toughness). For comparison, the sodium salts of the surfactants (NaDDS and NaDBS) were also used as fillers in LDPE. The X-ray diffraction results indicated that the hydrophobic LHS were exfoliated in the polymer matrix, whereas the hydrophilic LHS was only delaminated. In the LDPE composites, melting and crystallization temperatures were nearly constant, along with the crystallinity indexes. The mechanical properties were mainly varied when the organophilic LHS was used. Overall, fillers based on LHS, especially those containing hydrophobic anions, may be interesting alternatives in the production of reinforced thermoplastics.

O presente trabalho descreve a síntese e caracterização de hidróxidos duplos lamelares (HDL) de Zn/Al na razão molar 2:1, os quais foram intercalados com íons cloreto hidratados e ânions derivados dos corantes azo alaranjado de metila (AM) e alaranjado II (AII). Após caracterização, os materiais foram utilizados como cargas em polietileno de alta densidade (PEAD) e nanocompósitos foram preparados por extrusão e injeção, seguindo a norma ASTM D638-10. Os teores de cargas variaram de 0,1 até 2% (incluindo-se os sais de sódio dos corantes) e os nanocompósitos homogêneos foram avaliados em relação as suas propriedades estruturais, térmicas e mecânicas. De modo geral, após a adição das cargas existe somente uma pequena influência na temperatura de fusão e cristalização do PEAD. Para os HDLs contendo o pigmento intercalado com o ânion do corante AM e sais de sódio de ambos os corantes, as propriedades mecânicas apresentaram leve aumento do módulo e tensão de ruptura e diminuição do alongamento em relação ao polímero puro e um comportamento inverso foi observado para o ânion AII, além do HDL contendo ânions cloreto hidratados.

The present work describes the synthesis and characterization of Zn/Al layered double hydroxides (HDL) in the molar ratio 2:1, which were intercalated with hydrated chlorine ions and anions derived from the azo dyes methylorange (AM) and orange II (AII). After characterization, the materials were used as fillers into high density polyethylene (HDPE) and the nanocomposites were prepared by extrusion and injection, following the norm ASTM D638-10. The filler contents varied from 0.1 to 2% (including the sodium dye salts) and the homogeneous nanocomposites were evaluated in relation to their structural, thermal and mechanical properties. In general, after the fillers' addition there is only a small influence in the melting and crystallization temperature of HDPE. For HDLs intercalated with the anionic dye AM and both sodium dyes, the mechanical properties presented a small influence on Young's modulus and tensile strength and an increase in elongation compared to pure HDPE and an inverse behavior was observed for the anion AII, in addition to the HDL containing hydrated chlorine anions.