Synthesis of soluble polymers designed to degrade by intramolecular acid catalysis

International audienc

Synthesis of soluble polymers for medicine that degrade by intramolecular acid catalysis

International audienc

Adsorption of Polyisobutenylsuccinimide Derivatives at a Solid-Hydrocarbon Interface †

International audienceThe adsorption of polymer dispersants of the polyisobutenylsuccinimide series has been studied at the solid/xylene interface. Carbon black was studied as a model solid. Adsorption isotherms were determined, the enthalpy of adsorption was measured by calorimetry, and the thickness of the adsorbed layer was obtained from small-angle neutron scattering. The paper emphasizes the structure-properties relationships with the help of a series of polyisobutenylsuccinimides having different polyamine groups and different polymer architectures, simple diblock (PIBSI) and comblike structure (polyPIBSI). The polyamine part ensured a strong adsorption on the solid surface, which increased in strength with the number of amine groups. In the same way, changing the diblock structure for a comblike one led to an enhanced affinity of the polymer for the solid surface. The adsorption was enthalpic but the Gibbs free energy of adsorption remained moderate because of a large entropy loss during adsorption. There was an enthalpy-entropy compensation phenomenon. Below a concentration of 70 mmol/m 3 , the polymers adsorbed as a 30 Å thick monolayer and the adsorption phenomenon was irreversible, due to the polymeric nature of the polar part. A drastic increase of adsorbed amount took place for higher concentrations. The formation of reverse hemimicelles was assumed as the origin of this phenomenon. The supplementary adsorption was reversible, showing that the polymer-polymer interactions were weaker than the polymer-surface interactions

Adsorption of poly(isobutenylsuccinimide) dispersants at a solid-hydrocarbon interface

International audienceThe adsorption at the solid xylene interface of poly(isobutenylsuccinimides) (PIBSI) has been studied on carbon black by means of adsorption isotherms and small-angle neutron scattering. Simple diblock PIBSI having various chemical structures and poly(PIBSI) with a comblike structure were compared. The adsorption is due to the hydrophilic polyamine part. It was related to the chemical structure of the dispersants (length of the polyamine part, simple diblock structure versus comblike). The adsorption phenomenon was irreversible at low concentrations; the adsorbed macromolecules are fully stretched and form a monolayer of 30-Angstrom thickness. The consequences for the colloidal stability of carbon black dispersions in xylene were analyzed by means of quasielastic light scattering and rheology measurements

Synthesis, Characterization, and Evaluation of Polyisobutylene-Based Imido-Amine-Type Dispersants Containing Exclusively Non-Nucleophilic Nitrogen

Lubricating oils for gasoline and diesel engines are formulated to include amphiphilic dispersants for soot particle stabilization and prevention of particle aggregation. Primary and secondary amines used within the polar group of traditional dispersants provide basic nitrogen, which is able to neutralize acidic by‐products from combustion and does not contribute to sulfated ash. However, these active‐hydrogen‐containing amines present significant problems for fluoroelastomer seals and metals in terms of degradation and corrosion. Polyisobutylene (PIB)‐based dispersants containing only tertiary amines, intended to remediate these problems, were synthesized from primary‐bromide‐terminated PIB, 1‐(2‐aminoethyl)piperazine, and an anhydride such as phthalic anhydride. Intermediates and final dispersant molecules were characterized by NMR, GPC, TGA, and MALDI‐TOF MS. Using Langmuir adsorption studies with carbon black as a surrogate for soot, a direct dependence on the affinity for adsorption of the dispersant with respect to the number of phenyl rings present was identified. Performance testing revealed increased compatibility of the dispersants, including limited degradation of seals and corrosion of metals, while retaining total base number. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1657–167