The work focuses on the synthesis and layer by layer (LbL) assembly of oligoallylamine and phosphonated oligoallylamine.To this aim, the synthesis of oligoallylamine and the phosphonated form have been done by free radical polymerization in aqueous media. First, radical polymerization of acid salt of allylamine was performed. This charged polymer could not be characterized using classical analytical techniques such as size-exclusion chromatography and matrix-assisted laser desorption/ionisation-time of flight mass spectroscopy due to presence of cations. This work demonstrated the interest of capillary electrophoresis (CE) to analyze charged oligomers, using very small amounts of samples. Entangled polymer solution CE was used as a size-based separation technique for the characterization of the molar mass distribution using indirect ultraviolet detection and calibration based on vinyl pyridine standards. Phosphorus-containing oligoallylamines having a number-average molar mass of 1600 g mol21 and a 2.3 polydispersity index were obtained. When combined using the LbL approach, prepared polymers showed an exponential growth regime as demonstrated by Fourier transform infrared spectroscopy measurements. Furthermore, thermogravimetric analyses of the LbL-assembled polymers showed an extraordinary thermal and thermo-oxidative stability.