Chemical synthesis of hybrid inorganic-organic nanostructured corrosion inhibitive pigments and methods

Abstract

A method for preparing a hybrid inorganic-organic nanostructured inhibitive pigment, includes premixing a first stock solution containing one or more cations and a second stock solution containing one or more oxoanions to form a premixture under pH control in the presence of polymers as surface modifiers. The premixture is then reacted to form a slurry. The slurry is then quenched to separate nanoparticles from the slurry, followed by surface functionalization in organic inhibitors.

Claims

1. A hybrid inorganic-organic nanostructured inhibitive pigment formed by a hydrothermal process, comprising: two or more corrosion inhibitive species incorporated in the form of nanoparticles wherein the corrosion inhibitive species comprise one or more rare earth or transition metal cation nanoparticles that are uniformly distributed with an organic inhibitor and one or more oxyanion nanoparticles that are uniformly distributed with the organic inhibitor, the one or more rare earth or transition metal cation nanoparticles are selected from the group consisting of Zn.sup.2+, Ce.sup.3+, Pr.sup.3+ and combinations thereof; the one or more oxyanion nanoparticles comprise at least one of MoO.sub.4.sup.2−, PO.sub.4.sup.3−, and SiO.sub.3.sup.−; the organic inhibitor comprises at least one of 4,5-Diamino-2,6-dimercaptopyrimidine; 4,5-Diaminopyrimidine; Sodium diethyldithiocarbamate; 2-Mercaptopyridine; Thiophenol; 4-mercaptobenzoate; 2-mercaptobenzoate; 6-Mercaptonicotinate; 2-Mercaptonicotinate; 2-mercaptosuccinate; mercaptoacetate; and Sodium-mercaptopropionate.

2. The hybrid inorganic-organic nanostructured inhibitive pigment as recited in claim 1, wherein the organic inhibitor include amphiphilic molecules composed of a hydrophilic or polar moiety known as head and a hydrophobic or nonpolar moiety known as tail.

3. The hybrid inorganic-organic nanostructured inhibitive pigment as recited in claim 1, wherein the two or more corrosion inhibitive species are prepared from metal-ion-ligand/complex-polymer based precursor solutions via the hydrothermal process in combination with an in-situ follow-up surface modification processes with polymer surfactants.

4. The hybrid inorganic-organic nanostructured inhibitive pigment as recited in claim 3, wherein the polymer surfactants consist of at least one of acetylacetone polyacrylamide (PAM); phosphonate-polyethlene glycol (PEG); polyacrylic acid (PAA); propylamine phosphonate-polyethlene glycol (PEG); sulfonated acylate copolymer; polyvinyl pyrrolidone (PVP); and hydroxypropylcellulose (HPC).

5. The hybrid inorganic-organic nanostructured inhibitive pigment as recited in claim 1, wherein the nanoparticles are surface functionalized.

6. The hybrid inorganic-organic nanostructured inhibitive pigment as recited in claim 1, wherein the nanoparticles comprise an inorganic core and a porous polymer shell, and wherein the porous polymer shell is functionalized with the organic inhibitor.

7. A hybrid inorganic-organic nanostructured inhibitive pigment, comprising: two or more corrosion inhibitive species incorporated in the form of nanoparticles wherein the corrosion inhibitive species comprise one or more rare earth or transition metal cation nanoparticles and one or more oxyanion nanoparticles, wherein the nanoparticles comprise an inorganic shell having a porous polymer shell, and wherein a surface of the porous polymer shell is functionalized with an organic inhibitor, the one or more rare earth or transition metal cation nanoparticles are selected from the group consisting of Zn.sup.2+, Ce.sup.3+, Pr.sup.3+ and combinations thereof; the one or more oxyanion nanoparticles comprise at least one of MoO.sub.4.sup.2−, PO.sub.4.sup.3−, and SiO.sub.3.sup.−; the organic inhibitor comprises at least one of 4,5-Diamino-2,6-dimercaptopyrimidine; 4,5-Diaminopyrimidine; Sodium diethyldithiocarbamate; 2-Mercaptopyridine; Thiophenol; 4-mercaptobenzoate; 2-mercaptobenzoate; 6-Mercaptonicotinate; 2-Mercaptonicotinate; 2-mercaptosuccinate; mercaptoacetate; and Sodium-mercaptopropionate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows:

(2) FIG. 1 is a schematic of a hydrothermal process for hybrid inorganic-organic nanostructured inhibitive pigments; and

(3) FIG. 2 is a schematic of the synthesis of inorganic (core) and organic (shell) nanostructures for preparing a hybrid inorganic-organic nanostructured inhibitive pigment.

DETAILED DESCRIPTION

(4) FIG. 1 schematically illustrates a hydrothermal process 10 for preparation of a hybrid inorganic-organic (core-shell) nanostructured inhibitive pigment 100 (FIG. 2). The preparation of the hybrid inorganic-organic nanostructured inhibitive pigment 100 is via a chemical precipitation process, in combination with in-situ follow-up surface modification processes, i.e. polymer surfactants, pH control and organic inhibitors that provide an effective chromate alternative.

(5) Initially, at least a first stock solution 20, such as, for example only, zinc (Zn.sup.2+) citric complex solution (1:1), cerium (Ce.sup.3+) EDTA complex solution (1:1), or praseodymium (P.sup.3+) tartaric complex solution (1:1) is premixed with a second stock solution 30, as an example, such as molybdate (MoO.sub.4.sup.2−), phosphate (PO.sub.4.sup.3−), silicate (SiO.sub.3.sup.−), added with 1-2 w % polymers, such as polyacrylic acid (PAA) and Polyvinyl alcohol (PVA). The precursor solutions include the desired metal ions complexed with a chelating agent, and metal-oxide anions dispersed in polymer/surfactants (surface modifiers). The chelating agents include organic amines such as diethanolamine (DEA), and triethanolanine (TEA), as well as organic acids such as citric/oxalic/tartaric acid, etc. That is, two or more corrosion inhibitive species (i.e. Ce.sup.3+, Pr.sup.3+, Zn.sup.2+, VO.sub.3.sup.−, MoO.sub.4.sup.2−, PO.sub.4.sup.3−, SiO.sub.3.sup.− and organic molecules, etc.) are incorporated in the form of the inorganic (core)-organic (shell) nanoparticles as inhibitive pigments, prepared from metal-ion-ligand/complex-polymer based precursor solutions.

(6) The first stock solution 20 and the second stock solution 30 are, for example, communicated through respective high pressure pumps, 22, 32 to premix at a controlled pH 40. In this disclosed non-limiting embodiment, the flow rate is about 10-15 ml/min flow at 20° C. such that the pre-mixture is at 20° C., 25-50 MPa with the pH controlled to about 8-10 pH.

(7) The premixed solution is then reacted in a heated and pressurized reactor 50. In this disclosed non-limiting embodiment, the premixed solution is heated and pressurized with distilled water 52 at about 300° C.-400° C., 25-50 MPa to generate a hydrothermal process at a supercritical condition. The distilled water 52 is communicated through a high pressure pump 60 which, in this disclosed non-limiting embodiment, is at about 300° C.-400° C. at a flow rate of about, 50-70 ml/min.

(8) The reacted premixed solution produces a reaction product slurry 70 that is quenched and cooled by the distilled water 52. In this disclosed non-limiting embodiment, the distilled water is supplied at about 20° C., 25-50 MPa.

(9) The nanoparticles are then separated by a membrane filter, washed with distilled water, then dispersed in organic inhibitors for surface functionalization to provide the hybrid inorganic-organic nanostructured inhibitive pigment 100 (FIG. 2). A back-pressure regulator 90 may be utilized to control the separation.

(10) The chemical nature of the polymer/surfactant modified inorganic precursor core 108 with the organic porous polymer shell 110 (FIG. 2) composites allows combination with organic inhibitor additives 102 (FIG. 2) to produce the hybrid inorganic-organic nanostructured inhibitive pigment 100. The organic inhibitor additives include amphiphilic molecules composed of a hydrophilic or polar moiety known as head 104 and a hydrophobic or nonpolar moiety known as tail 106.

(11) Example organic inhibitor additives include, but are not limited to: 4,5-Diamino-2,6-dimercaptopyrimidine (C.sub.4H.sub.6N.sub.4S.sub.2); 4,5-Diaminopyrimidine (C.sub.4H.sub.6N.sub.4); Sodium diethyldithiocarbamate ((C.sub.2H.sub.5).sub.2NCSSNa); 2-Mercaptopyridine (C.sub.5H.sub.5NS); Thiophenol (C.sub.6H.sub.5SH); 4-mercaptobenzoate (C.sub.7H.sub.5O.sub.2S); 2-mercaptobenzoate (C.sub.7H.sub.5O.sub.2S); 6-Mercaptonicotinate (C.sub.6H.sub.5NO.sub.2S); 2-Mercaptonicotinate (C.sub.6H.sub.5NO.sub.2S); 2-mercaptosuccinate (C.sub.4H.sub.4O.sub.4S); mercaptoacetate (C.sub.2H.sub.3O.sub.2S); Sodium-mercaptopropionate (C.sub.3H.sub.5NaO.sub.2S).

(12) Example polymers/surfactants include: acetylacetone polyacrylamide (PAM); phosphonate-polyethlene glycol (PEG); and polyacrylic acid (PAA), propylamine phosphonate-polyethlene glycol (PEG); sulfonated acylate copolymer; polyvinyl pyrrolidone (PVP); and hydroxypropylcellulose (HPC).

(13) The hydrothermal process 10 provides one approach to synthesize a hybrid inorganic-organic nanostructured inhibitive pigments, having multiple corrosion protection modes for use as a chromate replacement. The nano-sized pigments reduce costs and improve coating performance as one challenge in applying nano-sized particles as pigments is the strong aggregation during their synthesis process commonly observed in nanoparticles that have been produced from the liquid phase. This agglomeration is, readily resolved by use of the disclosed in-situ surface modification technique during the pigment synthesis process.

(14) Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure.

(15) The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.