Poly(methyl methacrylate) as an Environmentally Responsive Capping Material for Aluminum Nanoparticles

Abstract

We present an investigation of the photochemistry of aluminum nanoparticles (Al NPs) capped with poly(methyl methacrylate) (PMMA). Powder X-ray diffraction and Fourier transform infrared spectroscopy with total attenuated reflection confirm the presence of crystalline aluminum cores and the PMMA cap and allow us to confirm the latter’s photodegradation upon exposure to UV light. The PMMA-Al NPs were also characterized by differential scanning calorimetry coupled with thermogravimetric analysis to study the thermal profiles for polymer combustion and metal oxidation exotherms. Transmission electron microscopy confirms that the Al NPs, around 36 nm in diameter, are embedded in the PMMA matrix. Following UV irradiation, the PMMA-Al NPs react considerably faster with alkaline solutions, compared with unphotolyzed samples. Photoactivation of the nanocomposite induces partial decomposition of the PMMA capping layer, exposing the underlying reactive metal cores to the surrounding environment and accelerating its redox reactivity. Photolysis times of 1, 6, 24, and 52 h were investigated to establish a minimum UV exposure time for the activation of the PMMA-Al NPs toward hydrolytic hydrogen gas generation.

Dual-functional organic surfactant for the effective stabilization of nano aluminium

“…The study showed no change in the intensity and width of the peaks corresponding to the pure aluminium in the XRD patterns, and there was no signature for the reflections of aluminium oxide. In comparison with previous studied (Table 2) on polymer-coated (PVA, PVP and PMMA) Al nanoparticles 11,13,15 or organic capping agents such as perfluoroalkyl carboxylic acids, oleic acid, epoxyhexane and epoxydodecane, [16][17][18][19][20] our dual-function surfactant established significant air stability for ah-Al that extended beyond 120 days. These findings indicate that the surfactant-stabilized ah-Al is stable for up to four months.…”

“…Reducing or avoiding the self-oxidation of highly reactive metals (such as Al, Zr and Mg) and decreasing the agglomeration of nanoparticles are the principal problems to be addressed for research into energetic materials to obtain nanoparticles with improved physical and chemical properties. [12][13][14][15][16][17][18][19][20][21] By nature, Al has more affinity towards oxygen. Therefore, preventing oxide formation on the surface of the aluminium nanoparticles is a challenge.…”

“…Reducing or avoiding the self-oxidation of highly reactive metals (such as Al, Zr and Mg) and decreasing the agglomeration of nanoparticles are the principal problems to be addressed for research into energetic materials to obtain nanoparticles with improved physical and chemical properties. 12–21…”

Synthesis of submicron aluminum particles via thermal decomposition of alkyl aluminum precursors in the presence of metal seeds and their application in the formation of ruthenium aluminides

“…The second synthetic approach is the catalytic decomposition of alanes. Within this approach amine alanes such as H 3 AlNMe 2 Et [11,[16][17][18], H 3 AlNMe 3 [19], H 3 AlNEt 3 [20], H 3 AlN(C 4 H 8 )(CH 3 ) [17] or H 3 AlNMePyr [21] are decomposed using Ti(OiPr) 4 [11,16,17,19] or TiCl 4 [21] as a catalyst. The ether adducts of AlH 3 are known to decompose under similar conditions [22], their use in the wet chemical synthesis of Al nanoparticles is however much more uncommon compared to their amine counterparts.…”

“…Uncontrolled oxidation can be avoided applying various passivating agents such as oleic acid [18,23,28], perfluorated carboxylic acids [19,21,29], phosphines [12], amines [30], or thin transition metal coatings [20]. Also, polymers like PVP [31], PMMA [16], and polyepoxides [32,33] can be used to protect the surface.…”