Research On The Surface Connection Of Alkyl Phosphonic Acid Modified Nano-Ni/Cu

Class-II hybrid materials can be obtained by surface modification of an inorganicsupport. As modifiers, organophosphorus acids and their derivatives are findingincreasing applications. Dislike organosilicon modifiers, organophosphorus acids arestable toward hydrolysis, which make it easier to perform surface modification withorganophosphourus acids in water. The ease of formation and the stability of P―O―M (M is metal) bonds make organophosphorus acids more competitive. In advantagesof simple molecular structure and less deputy reaction, Alkyl Phosphonic acids are acommonly used kind of organophosphorus acids.In this research, we studied the influence of the length of carbon chain and theamount of modifier on surface modification of different kind of nano-metals, and thenspeculate the surface connection of the modified nano-metal particles.n-Hexadecylphosphonic acid (HDPA), n-Dodecylphosphonic acid (DDPA) andn-Octylphosphonic acid (OPA) are used to modify the surface of nano Ni/Cu indifferent amount of modifier (1/2M,1M,2M). According to the results, there are threekinds of materials on the surface of modified nano-Ni/Cu, which are surface adsorption,extra Phosphonic acid molecules bonded by hydrogen bond and Phosphonic acidgroups bonded by covalent bond. The surface adsorption and extra Phosphonic acidwere taken off the surface during heating, which forms the first “step” on the TGAcurve, and the taking off of the Phosphonic acid groups showed the second “step” onthe TGA curve, which was seperated by the temperature of300degree (Ni) and350degree (Cu) with the first one. In addition, the dividing temperature line of2Mmodified namo-Ni/Cu was a little higher than1M or1/2M modified nano-Ni/Cu. In thecondition of not excessive, the longer the carbon chain and the more modifier, thebetter modification on nano-Ni, which means the best modification of nano-Ni ismodified by HDPA in1M amount. In terms of nano-Cu, there was no limitation ofexcessiveness, which means the best modification is modified by HDPA in2Mamount.By speculating the surface connection of alkyl Phosphonic acid modifiednano-Ni/Cu, we found that there are multiple connection between the Phosphonic acid molecules and the surface of nano-Ni, such as P―O―Ni and P―Ni bonds, but theconnection on the surface of nano-Cu was simple, only P―O―Cu bond. The P―O―M (M is Ni, Cu) bond would be broken during heating, while P-Ni bond would not.