Basic surface-active properties in the homologous series of β-alkyl (C12H25/C18H37) polyethyleneoxy (n = 0-20) propionamides

Abstract

BackgroundHeterogeneous β-Alkyl (C12H25/C18H37) polyethyleneoxy (n = 0-20) propionamides [R(EO)nPD] represent new “hybrid” nonionic-ionic colloidal structures in the field of surface-active products (technical products). These “niche” compounds have three structural and compositional characteristics that also define their basic colloidal properties: mixture of R and PEO chain homologues; specific conformations due to the PEO chains; and the presence of side products from the addition of higher alcohols, polyethyleneglycols and traces of water to acrylamide. The proposed major objective of this paper is the basic informative colloidal characterization (functional classification, HLB balance, surface tension, critical micelle concentration) in direct correlation with the structural changes in the homologous series of LM(EO)nPD and CS(EO)nPD. The structures were obtained either indirectly by cyanoethylation followed by partial acid hydrolysis of the corresponding β-propionitriles, or directly by the nucleophilic addition under alkaline catalysis of linear higher alcohols C12H25/C14H29 (7/3) (LM) and C16H33/C18H37 (CS) as such and heterogeneous polyethoxylated (n = 3-20) to acrylamide monomer, through an adapted classic reaction scheme.ResultsIn the series of basic colloidal characteristics investigated the structure-surface activity dependence is confirmed. Their indicative character for R(EO)nPD is based on the assumption that the structures studied are not unitary (heterogeneous) because: a) the hydrophobic chains C12H25/C18H37 have been grouped in two variants, C12H25/C14H29 (LM); C16H33/C18H37 (CS), each with an internal mass ratio of 7/3; b) the hydrophilic polyoxyethylene chains (n = 3-20) have polydisperse character; the meaning and value the oligomerization degree, n, is that of weighted average. In these conditions the surface tension increases proportionally with the oligomerization degree of the polyoxyethylene chain, while the critical micelle concentration decreases in the same homologous series as well as with the increase of the hydrophobic chain in the C12H25 to C18H37 series. A mechanism of micellization is proposed, consistent with the experimental data recorded and the hypotheses known from the consulted literature.ConclusionsThe idea of the obtaining and basic colloidal characterization of heterogeneous R(EO)nPD is justified. The knowledge and constructive approach of the heterogeneous character confirm the basic surface-active potential of R(EO)nPD, the structure-colloidal characteristics dependence and justifies further, more extensive research.

Effect of Certain Ethylene Oxide Heterogeneous Heterobifunctional Acyclic Oligomers (HEHAO) on Wetting

“…In the reaction scheme accessed [5], heterogeneously polyethoxylated (n*=3, 6,9,12,16,20) C 12 H 25 /C 14 H 29 (7/3) (LM) higher alcohols and heterogeneously polyethoxylated (n*=3, 6,9,12,16,20) C 16 H 33 /C 18 H 37 (7/3) (CS) higher alcohols, respectively, were technical products obtained by the base-catalyzed reaction of the higher alcohols above with ethylene oxide [3,40].…”

“…The polyethoxylated C 12 H 25 /C 14 H 29 (7/3) (LM) (n*=3, 6,9,12,16,20) and C 16 H 33 /C 18 H 37 (7/3) (CS) (n*=3, 6,9,12,16,20) higher alcohols can be considered as monoderivatized polyethyleneglycols (primary PEGylation fragment). There are many possibilities for modifying the determinant hydrophobic fragment between the C 12 H 25 /C 14 H 29 and C 16 H 33 /C 18 H 37 [40].…”

“…Due to their composition, specific primary and secondary (conformational) structures, HEHAO have a pronounced heterogeneous character. The idea of their basic colloidal characterization becomes indicative, being the resultant of the colloidal manifestation of 24 unitary homologous structures (4 hydrophobic R series, each with 6 hydrophilic PEO series) [1,3,4,40].…”

“…The main colloidal characteristics of the surface-active compounds (technical products) depend on their structure and heterogeneous composition [3,40]. Laboratory evaluations performed on the homologous series (n*=0-20) of the two sets of HEHAO purified prior to the synthesis fall into this casuistry.…”

“…Laboratory measurements allowed the establishment of structure-surface-activity correlations, following that the absolute, comprehensive assessment on the scope to involve the investigation under conditions of actual equipment, support, float, etc. The main surface-active properties previously considered [3,40] were: surface tension (σ) and critical micelle concentration (CMC), foaming with its three aspects [foamability (F), foam stability (FS), foam density (FD)], wetting effect (U), the softening-antistatic effect (LA) and the washing effect (WE), respectively [1,3,4,7,18,19,33].…”