Poly(amidoamine) dendritic structures, bearing different end groups, as adhesion promoters for urea–formaldehyde wood adhesive system

Abstract

A series of core-shell poly(amidoamine) (PAMAM) dendritic compounds bearing different end groups such as AOH, NH 2 , and NH 3 þÀ Cl up to the third generation were prepared via successive Michael addition of a nucleophilic core (ethylenediamine) to methylacrylate followed by amination steps using ethylenediamine for the amine-terminated while ethanolamine for the hydroxyl-terminated compounds, also the protonated ammonium salt terminated form was obtained by cationization of the amine-terminated form using hydrochloric acid solution. The Surface activity and aggregation behavior of the corresponding aqueous solutions of the prepared generations with their different end groups were studied and confirmed by surface tension measurements using ring method technique. The prepared dendrimers showed high surface activity and the measurements revealed their ability to self aggregate in water at very low concentrations, critical aggregation concentrations (CACs). The CACs were found to decrease with increasing the generation number, which implies that molecular weight and structure play important rules in controlling the surface activity and CAC. The dendritic compounds proved to be effective as adhesion promoters for urea formaldehyde (UF) resins when applied as wood adhesive systems, which was ascribed in partial to the improved wetting over the substrate, a role that is fundamentally related to the huge number of function groups present at the interface.

Developing an ultra non-fouling SU-8 and PDMS hybrid microfluidic device by poly(amidoamine) engraftment

“…Moreover, it is interesting to note that the roughness of PAMAM modified surfaces increased with increasing PAMAM concentration used to modify the surfaces. This is likely due to increased PAMAM dendrimer aggregation on the resulting surfaces [41,42]. In addition, a closer analysis of the AFM images reveals that almost all SU-8 surfaces were more uniform and better organized than the PDMS surfaces.…”

Hyperbranched Poly(amidoamine)s as Additives for Urea Formaldehyde Resin and Their Application in Particleboard Fabrication

“…In brief, this hyperbranched polymer, HB(MA-EDA)3, was not suitable for the modification of UF resins as particleboard binders, at least when it was added as a final additive. This may imply the necessity for starting the modification of UF resins with this modifier in the early steps of the resin preparation to ensure effective insertion into the network structure (Essawy et al 2009;2010;Essawy and Mohamed 2011). To enhance the water resistance of the MUF resin, these reactive PAMAMs were also used as additives to adjust the pH at the end stage instead of using sodium hydroxide, as in a previous study (Amirou et al 2014).…”

“…The highly branched and three-dimensional architecture of these macromolecules have attracted considerable attention in the past few decades (Uhrich et al 1992;Frechet 1994;Inoue 2000). In addition to numerous applications in various fields such as medicine, chemistry, materials science, biology, and physics, there is interest in the use of dendrimers as modifiers for wood adhesives (Essawy et al 2009;2010;Essawy and Mohamed 2011;Zhou et al 2013;. The dendritic poly(amidoamine)s (PAMAMs) are among the most widely used dendrimers as a result of their ready commercialization.…”

“…Full, as well as half, of the generations of dendritic PAMAMs have been introduced into a UF wood adhesive system as modifiers (Essawy et al 2009), revealing that PAMAMs are reactive modifiers for the UF wood adhesive system and can increase the stability of the UF resin and enhance the performance of the bonded wood joints. In addition, a series of core-shell PAMAM dendritic compounds bearing different end groups such as -OH, -NH2, and NH3 +-Cl up to the third generation have been used as modifiers for UF resins (Essawy and Mohamed 2011). The results revealed that the prepared dendrimers had a reasonable surface activity, and the measurements suggested their ability to self-aggregate in water at very low concentrations and critical aggregation concentrations.…”

Effect of addition of glycolysis products of poly(ethyleneterephthalate) wastes to urea‐formaldehyde resin on its adhesion performance to wood substrates and formaldehyde emission

“…These fractions showed acid value up to 17.44 mg KOH/g while about 10-folds of equivalent hydroxyl number (174.41 mg KOH/g). The existence of such high hydroxyl number gives rise to their capability to incorporate in the network formation during gelation or crosslinking while the extremely shorter shelf-life (maximum 2 months for most of the samples) relative to our previous studies based on modification of UF resins with dendritic poly(amidoamines) (PAMAM) (14)(15)(16)(17) is ascribed to availability of ACOOH groups in reasonable amount that can selfcatalyze the condensation reactions during storage and therefore shorten the shelf life.…”