METAL SURFACE TREATMENT

Abstract

The instant invention concerns the use of at least one polymer P obtained by radical copolymerization of a mixture of (i) acrylic acid; (ii) optionally methacrylic acid; and (iii) at least one ethylenically unsaturated monomer carrying an unsaturated heterocycle having at least two nitrogen atoms, said monomer being preferably an ethylenically unsaturated imidazole, for treating a metallic surface for treating a metallic surface intended to be coated by a paint, a varnish or an adhesive, for example intended to be adhesive-bonded to another surface, in order to impart a resistance to the adhesive failure to the resulting bonding.

Claims

1. A method for treating a metal surface intended to be coated by a paint, a varnish or an adhesive, the method, comprising applying onto the metal surface at least one polymer P obtained by radical copolymerization of a mixture of (i) acrylic acid; (ii) optionally methacrylic acid; and (iii) at least one monomer M which is an ethylenically unsaturated monomer carrying an unsaturated heterocycle having at least two nitrogen atoms, said monomer M comprising an ethylenically unsaturated imidazole having the Formula (I) below: ##STR00009## wherein: R.sup.1 is H or a methyl group —CH.sub.3; and A is a linkage selected from the group consisting of: a single covalent bond; and a spacer group.

2. The method according to claim 1, wherein the polymer P is used for treating a first metallic surface (S1) intended to be bonded to a second surface (S2) by adhesive bonding, and for imparting a resistance to the adhesive failure to the bonding.

3. The method according to claim 2, for further imparting to the bonding a resistance to corrosive atmospheres and to wet atmospheres.

4. The method according to claim 1, wherein polymer P further comprises below 10 mol % of one or more further monomers M′ selected from the group consisting of hydrophobic monomers and amphiphilic monomers selected from the group consisting of i) monoethyl maleic anhydride ester, diethyl maleic anhydride ester, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate ii) monohydroxyethyl maleic anhydride ester, dihydroxyethyl maleic anhydride ester, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate iii) poly(propylene oxide)-b-poly(ethylene oxide) maleic acid half ester iv) poly(propylene oxide)-b-poly(ethylene oxide)-ethyl (meth)acrylate v) poly(propylene oxide)-b-poly(ethylene oxide) (meth)acrylate, alkyl-poly(ethylene oxide) (meth)acrylate vi) vinyl acetate, vinyl propionate. provided the total amount of (i) acrylic acid and optionally (ii) methacrylic acid is at least 60% mol.

5. The method according to claim 4, wherein the proportion in mol of monomers M′ is below 5 mol %.

6. The method according to claim 1 wherein the polymer P is obtained by radical copolymerization of a mixture consisting of: (i) acrylic acid; and (ii) optionally methacrylic acid; and (iii) at least one monomer M which is an ethylenically unsaturated monomer carrying an unsaturated heterocycle having at least two nitrogen atoms, said monomer M being an ethylenically unsaturated imidazole having the Formula (I).

7. The method according to claim 1, wherein the polymer P is obtained by radical copolymerization of a mixture having the following molar ratio, based on the total quantity of acrylic acid, methacrylic acid and monomer M of formula (I): acrylic acid: from 5 to 95% methacrylic acid: from 0 to 90% monomer M: from 1 to 50%.

8. The method according to claim 1, wherein the polymer P has a number average molecular weight of at least 7,500 Da.

9. The method according to claim 2, wherein the metal surface (S1) is a surface comprising a metal selected from aluminum, steel, zinc, magnesium titanium, copper and their alloys, or cobalt-nickel alloys.

10. The method according to claim 9, wherein the metal surface (S1) is a surface of aluminum or aluminum alloy.

11. The method according to claim 2, wherein the second surface (S2) is a metallic surface.

12. The method according to claim 2, wherein the second surface (S2) is a non-metallic surface.

13. The method according to claim 2, wherein the polymer P is used for treating both surfaces (S1) and (S2) before the adhesive bonding of the two surfaces.

14. (canceled)

15. A composition including a polymer P obtained by radical copolymerization of a mixture of (i) acrylic acid; (ii) optionally methacrylic acid; and (iii) at least one monomer M which is an ethylenically unsaturated monomer carrying an unsaturated heterocycle having at least two nitrogen atoms, said monomer M comprising an ethylenically unsaturated imidazole having the Formula (I) below: ##STR00010## wherein: R.sup.1 is H or a methyl group —CH.sub.3; and A is a linkage selected from the group consisting of: a single covalent bond; and a spacer group selected from —CO—NH—(CH.sub.2).sub.n— or —CO—O—(CH.sub.2)n-, wherein n is an integer from 1 to 5.

16. A process for bonding a first metallic surface (S1) with a second surface (S2), comprising: treating the first surface (S1) with at least one composition including at least one polymer P according to claim 15; and optionally treating the second surface (S2) with at least one composition including at least one polymer P according to claim 15; and bonding the surfaces (S1) and (S2) via an adhesive composition applied between the two surfaces.

17. The process according to claim 16, wherein the composition comprising the polymer P is: a conversion composition including a polymer P; and/or a solution or a dispersion of the polymer P, optionally applied on the surface after having applied a conversion coating on the surface to be treated; and/or the adhesive composition, that comprises the polymer P.

18. A material comprising two adhesive-bonded surfaces including a first metal surface comprising a metal surface (S1) which is in all or part (i) treated with a polymer P and (ii) bonded to a second surface (S2), via an adhesive, said material being typically a material having a metal surface (S1) in all or part covered by: at least one coating comprising at least one polymer P; and/or a layer comprising a reaction product of the polymer P with a metal of the treated surface or another compound present in said layer, or a polymer P strongly linked with said other compound, wherein the polymer P is obtained by radical copolymerization of a mixture of (i) acrylic acid; (ii) optionally methacrylic acid; and (iii) at least one monomer M which is an ethylenically unsaturated monomer carrying an unsaturated heterocycle having at least two nitrogen atoms, said monomer M comprising an ethylenically unsaturated imidazole having the Formula (I) below: ##STR00011## wherein: R.sup.1 is H or a methyl group —CH.sub.3; and A is a linkage selected from the group consisting of: a single covalent bond; and a spacer group such as a group —CO—NH—(CH.sub.2).sub.n— or —CO—O—(CH.sub.2)n-, wherein n is an integer from 1 to 5.

19. The method of claim 1, wherein monomer M comprises an ethylenically unsaturated imidazole having the Formula (I) below: ##STR00012## wherein: R.sup.1 is H or a methyl group —CH.sub.3; and A is a linkage selected from the group consisting of: a single covalent bond; and a spacer group.

20. The method of claim 19, wherein the spacer group is —CO—NH—(CH.sub.2).sub.n— or —CO—O—(CH.sub.2)n.

Description

EXAMPLES

Example 1

[0122] Polymers according to the invention, obtained by a copolymerization of a mixture of acrylic acid, methacrylic acid, and N-Vinylimidazole (VIm), were tested in these examples.

Example 1.1

[0123] The polymer P1 (AA/MAA/VIm 26/70/04 mol/mol/mol) has been prepared as follows: [0124] Solution 1: 7.8 g of 2,2′-Azobis(2-methylpropionamidine)dihydrochloride (V50) at 97% are dissolved in 68.3 g of water. [0125] Solution 2a (AA/VIm=26/04 mol/mol): 35.4 g of AA and 7 g of VIm are diluted in 17.6 g of water. [0126] Solution 2b: caustic solution at 35% in water (113 mL). [0127] Solution 3: 114 g of MAA are diluted into 74 g of water. [0128] Solution 1, along with 5% of Solution 2a and 114 g of deionized water are charged at room temperature into a 700 ml reactor fitted with adequate stirring, inlets, feeding and temperature control devices.

[0129] The reactor temperature is then heated to 60° C. within 1 hour, with nitrogen degassing. When temperature has reached 60° C., two feeds are started, under nitrogen blanket: [0130] the remaining 95% of Solution 2a over 4 h, along with Solution 2b [0131] Solution 3, over 5 hours

[0132] Once the longest feed is over, the reaction mixture is maintained for two additional hours at 60° C., before it is cooled down to room temperature.

[0133] The smooth incorporation of monomers was monitored by 1H NMR spectroscopy over the polymerization and the final product was analyzed by both 1H NMR spectroscopy and size exclusion chromatography.

[0134] A Brucker 300 MHz spectrometer was used to record proton nuclear magnetic resonance (.sup.1H NMR) spectra. To measure AA, MAA and VIm conversions, four drops of the reaction mixture were diluted in around 1 g of deuterated water (D.sub.2O). AA conversion >99.6%; MAA conversion >99.9%; VIm conversion>99.9%

[0135] Average molecular weights were measured by Size Exclusion Chromatography (SEC) equipped with a MultiAngle Laser Light Scattering (MALLS) Mini Dawn TREOS detector and an Agilent concentration detector (RI detector). The SEC system is running on three columns Varian Aquagel OH mixed H, 8 μm, 3*30 cm at a flow rate of 1 mL/min and with the following mobile phase: 100% water, 100 mM NaCl, 25 mM NaH2PO4, 25 Mm Na2HPO4, buffer pH=7. Polymer samples were diluted down to 0.5 active wt % in the mobile phase for at least 4 hours then filtrated in a Millipore filter 0.45 μm and 100 microliters were injected in the mobile phase flow. Absolute molar masses were obtained with the dn/dC of the poly(acrylic acid) equal to 0.1875 mL/g. M.sub.n=29.5 kg/mol; M.sub.w=76 kg/mol; polydispersity index Ð=2.6.

Example 1.2

[0136] The same process was used to prepare the polymer P2 (AA/MAA/VIm 20/70/10 mol/mol/mol): [0137] Solution 1: 7.0 g of 2,2′-Azobis(2-methylpropionamidine)dihydrochloride (V50) at 97% are dissolved in 60.7 g of water. [0138] Solution 2a (AA/VIm=20/10 mol/mol): 24.2 g of AA and 15.8 g of VIm are diluted in 16.6 g of water. [0139] Solution 2b: caustic solution at 35% in water (129 mL). [0140] Solution 3: 101 g of MAA are diluted into 66 g of water. [0141] AA conversion=99%; MAA conversion>99.9%; VIm conversion>99.9% [0142] M.sub.n=41 kg/mol; M.sub.w=107 kg/mol; polydispersity index Ð=2.6.

[0143] Performances of polymers P1 and P2 were assessed with AA 5754 type H111 aluminum alloys coupons from FBCG (100 mm long, 25 mm wide, 3 mm thick) through Single Lap Shear (SLS) tests, before and after ageing in corrosive conditions. Coupons were prepared according to the protocol below and assembled to form Single Lap assemblies as described in D1002-10. [0144] Step 1—20 coupons are cleaned and etched all together in one single step, combining cleaning and etching, in a 4 L bath at 50° C. contained in a stainless steel tank, typically made by diluting a commercially available formulation, Chemtec DBT ALU 200, available from Chemtec Aertec (5 g of DBT ALU 200 into 995 g of water) for 3 min. under light stirring. The coupons were then rinsed twice during 1 min. with deionized water. [0145] Step 2—the coupons are then pre-treated by dipping for 2 min. in the treatment bath, containing the polymer at 50° C. and at several concentration indicated in the Table 1 below. They are then rinsed altogether with a flow of deionized water for 1 min. and dried for 30 min. at 60° C. [0146] Step 3—the coupons are then assembled in pairs, each pair forming a so called single lap shear “assembly”: two coupons are placed horizontally, parallel, one above the other forming an overlap of 12.5 mm long and 25 mm wide (“overlap zone”, including one of terminal zone of each of the two coupons of 25 mm wide, namely the last 12.5 mm of the 100 mm length of the coupon). A structural high temperature curing epoxy adhesive bead (Betamate 1496, from Dow) is applied with a gun under 7 bars on the overlap zone of the lower coupon. The upper coupon is then pressed, thus forming a bonding zone of 12.5 mm long, and 25 mm wide. Paper clips are used to maintain the assembly integrity before and during curing. The adhesive is then cured according to adhesive producer guidelines, typically for 40 min. at 180° C. Finally, paper clips are removed. [0147] Step 4—tensile strength test I on assemblies as obtained in step 3

[0148] Used material: Zwick/Roell—Z50, with jaws grasping assembly tips over 50 mm and a pulling speed of 10 mm/min. (each jaw holds one of the bonded coupon of the pair, on a grasping zone of 50 mm of said coupon located at the end zone of each coupon opposite to the overlap zone. The jaws are then moved for pulling each of the coupon horizontally in the direction starting from the bonding zone towards the grasping zone) [0149] Step 5—tensile strength test II performed on assemblies as obtained in step 3 after ageing [0150] 5.1. Ageing Cyclic Test [0151] A cyclic ageing test is performed according to ASTM G85—Annex 3 (SWAAT, 2011) [0152] in a corrosion chamber Q-FOG CRH 600L, from Q-FOG [0153] in the following conditions: [0154] a 30-min. acidified salt fog spray followed by [0155] a 90-min. soak at >98% relative humidity [0156] under the following conditions: [0157] Chamber temperature—constant 49° C. [0158] Air saturator temperature—constant 57° C. [0159] Relative humidity—>98% [0160] pH of fall out solution—2.8-3.0 [0161] Volume of fall out solution—1.0-2.0 ml/80 cm.sup.2/hour [0162] Exposure period—1000 hours [0163] After the exposure period is completed, the assemblies are washed down with lukewarm water to remove and neutralize excess acid and any remaining salt residues. All assemblies were then air dried using forced ambient temperature before being for submitted to lap-shear tensile testing. [0164] 5.2. Tensile Strength Test [0165] In the conditions of the tensile strength test I of step 4

[0166] The obtained results are reported in Tables 2 to 5 below (the values are average values: the tests were performed on 3 assemblies before ageing and on five assemblies after ageing), with the following variations in step 2. Polymers were diluted with de-ionized water and the resulting treatment bath was tested as such (no pH adjustment, “native pH”) or after acidification (pH adjusted with sulfuric acid):

TABLE-US-00001 TABLE 1 conditions of steps 1 and 2 Step 2: surface treatment Polymer Test Step 1: surface concentration pH of no. degreasing & etching Polymer in the bath the bath 1.1 3 min.-dip in Chemtec NONE — — DBT ALU 200 (con- at 50° C. followed trol) by a 1 min.-rinse 1.2 same P1 1000 ppm 2.5 (pH adjusted with sulfuric acid) 1.3 same P1 1000 ppm 8.5 (native pH) 1.4 Same P2 1000 ppm 8.4 (native pH)

[0167] Below are reported performances before ageing, after ageing, and the ratio between values after ageing and values before ageing, called “retention”:

TABLE-US-00002 TABLE 2 Maximum LOAD Maximum LOAD Before ageing (test I) After ageing (test II) maximum maximum load STD load STD Retention Test no. (N) (N) (N) (N) (%) 1.1 (control) 10838 218 3862 4293 36 1.2 8278 473 6669 409 81 1.3 9182 349 6855 288 75 1.4 9050 79 7263 278 80

TABLE-US-00003 TABLE 3 STRAIN measured at the maximum load STRAIN measured at the maximum load Before ageing (test I) After ageing (test II) Strain STD Strain STD Retention Test no. (MPa) (MPa) (MPa) (MPa) (%) 1.1 (control) 35 0.7 12 14 36 1.2 26 1.5 21 1.3 81 1.3 29 1.1 22 0.9 75 1.4 29 0.3 23 0.9 80

TABLE-US-00004 TABLE 4 ENERGY measured at the maximum load ENERGY measured at the maximum load Before ageing (test I) After ageing (test II) maximum maximum Energy STD Energy STD Retention Test no. (J) (MPa) (J) (MPa) (%) 1.1 (control) 12 0.8 3 4 24 1.2 14 3 4 0.4 31 1.3 22 3 7 1.3 32 1.4 20 0.8 9 2 45

TABLE-US-00005 TABLE 5 FACIES after bond failure FACIES after failure*** Test no. Before ageing (test I) After ageing (test II) 1.1 (control)  c ~a 1.2 ~c a/c 1.3 ~c a/c 1.4 ~c a/c ***: c: cohesive fracture a: adhesive fracture a/c: adhesive and cohesive fracture ~c: rather cohesive fracture * actual performance

[0168] Polymers according to the invention, with an amidopropyl spacer between the polymer backbone and the imidazole group are described in Example 2:

Example 2

[0169] The polymer P3 (AA/methacrylamido propyl imidazole 92/08 mol/mol) was prepared as follows:

Poly(Acrylic Acid) Synthesis Via Reversible-Deactivation (Controlled) Radical Polymerization:

[0170] 219 ml of DI water and 69 ml of methanol were taken in a round bottom flask. 30 g of acrylic acid was added to the round bottom flask and the reaction mixture was stirred till the solution became homogeneous. 0.32 g of Rhodixan A1 as a controlling agent was then added to the solution. The solution was then purged with N.sub.2 for 1 hour. 0.4048 g of VA-044 initiator (2,2′-Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, TCI) was added to reaction mixture and continued purging for 15 min. The polymerization was carried out at 60° C. for 5 hours under N.sub.2 atmosphere. The reaction mixture was then exposed to air and an aliquote was taken in D20 for recording proton NMR spectrum (1H NMR) using NMR (Bruker 400 MHz). It confirmed complete conversion of the acrylic acid monomer. The polymer was precipitated in acetone, dissolved in water and precipitated in acetone again. The precipitated polymer was dried at 60° C. for 12 hours under vacuum.

[0171] Average molecular weights were measured by Gel Permeation Chromatography (GPC) using Waters 515 instrument equipped with column oven, empower software (GPC module), Shodex RI-71 Detector. The SEC system is running on polymer Lab Aquagel-OH-50 (Linear MW operating range: 500 to 600,000 g/mol, PS equivalent) columns with Guard column, a flow rate of 1 mL/min. and with the following mobile phase: 0.25M NaNO.sub.3+0.03M Na.sub.2HPO.sub.4+0.003M NaN.sub.3-pH-9. Dilute solution of polymer samples at 10 mg/ml were prepared in the mobile phase and then filtrated via a Millipore filter 0.2 μm before injecting to the system and 100 μL were injected in the mobile phase flow with a run time of 30 min. The measurement was carried out at 40° C. Poly(acrylic acid-Na salt) (Polymer Lab-PL2140-0100) was used as the calibration standard. Results are: M.sub.n=26,000 g/mol, M.sub.n=57,000 g/mol, polydispersity index=2.17.

Synthesis of an Amino Propyl Imidazole Functionalized Poly(Acrylic Acid) (Polymer P3) by Conventional DCC (Dicyclohexylcarbodiimide) Coupling Reaction in Organic NMP Solvent:

[0172] In a 500 ml round bottom flask equipped with a water condenser and a mechanical agitation, were introduced at room temperature (22° C.), 25 g of Poly(acrylic acid) (PAA; synthesized as described above) and 100 ml of NMP. The mixture was degassed by bubbling nitrogen in the bulk for 30 min. at room temperature. Then the reaction mass was heated to 60° C. with constant stirring for overnight under nitrogen atmosphere. After complete dissolution of PAA, 7 g of DCC (Sigma Aldrich) was added slowly under stirring at 60° C. for 30 min., followed by addition of 4.34 ml of aminopropyl imidazole (Sigma Aldrich) within 20 min.; the reaction medium was then at 70° C. for 48 hours.

[0173] The polymer was precipitated in ethyl acetate:THF (1:1) mixture, dissolved in MeOH and re-precipitated in ethyl acetate. The polymer was dried in vacuum-oven at 70-75° C. for 24 hours. The yield of the polymer was around 90%.

[0174] The percentage of propyl imidazole groups introduced in the polymer was calculated by recording proton NMR spectrum (.sup.1H NMR) using NMR (Bruker 400 MHz). Around 20 mg of the polymer was dissolved in deuterated water (D20) to record the spectrum. The result is: acrylic acid units/imidazolepropyl acrylamide units=92/8 mol/mol.

[0175] Polymers according to the invention, with imidazolinium groups are described in Example 3 and 4:

Example 3

[0176] The polymer P4 was prepared by full quaternization of polymer P3 with bromo-hexane)

[0177] In a 250 ml round bottom flask equipped with a water condenser and a mechanical agitation, were introduced at room temperature (22° C.), 7 g of aminolmidazole (8 mol %) functionalized PAA (Polymer P3, from example 2) and 70 ml of NMP. The mixture was degassed by bubbling nitrogen in the bulk for 30 min. at room temperature. After complete dissolution of the polymer, 11.88 g of bromohexane (Sigma Aldrich) was added and allowed to stir at 90° C. under nitrogen atmosphere for 24 hours.

[0178] The polymer was precipitated in ethyl acetate:THF (1:1) mixture, re-dissolved in methanol and re-precipitated in ethyl acetate. The polymer was dried in vacuum-oven at 70-75° C. for 24 hours. The yield of the functional polymer was about 50%.

[0179] The percentage of quaternization of the imidazole group on the polymer backbone was calculated by recording proton NMR spectrum (.sup.1H NMR) using NMR (Bruker 400 MHz). Around 20 mg of the polymer was dissolved in deuterated methanol to record the spectrum. Complete quaternization of the polymer was observed (acrylic acid units/imidazolium hexyl bromide units=92/08 mol/mol).

[0180] The bromide content of the polymer was also calculated by using argentometric titration. Details of the instrument utilized for the measurement are as follows: Metrohm Autotitrator 905, equipped with Ag/AgCl electrode (Metrohm part number: 6.0450.100) and Tiamo software (Version 2.5) as well as analytical balance with capability to weigh up to 0.0001 mg. Following reagents were utilized (obtained from Sigma Aldrich) [0181] 1. Methanol [0182] 2. 0.01N Silver Nitrate solution (AgNO.sub.3)-Standardize before performing experiment using Anhydrous Potassium Chloride (KCl) in water [0183] 3. Potassium Chloride (KCl) [0184] 4. 50% v/v Aqueous Nitric acid (HNO.sub.3) [0185] 5. Milli Q water (Deionized water)

[0186] Sample preparation and Titration: Quarternized polymer (0.0050 to 0.0060 g) was weighed and dissolved in 30 ml of methanol and stirred till sample is completely dissolved. 50% v/v aqueous HNO.sub.3 (3-4 drops) were added to acidify the sample solution. The solution was titrated against 0.01N AgNO.sub.3 solution using Ag/AgCl electrode. And the end point was noted down as EP1.

μeq/g of Ionic Bromide=(EP1*1000*Actual Normality of AgNO.sub.3)/wt. of the sample in (g)

ppm of Ionic Bromide=μeq/g of Ionic Bromide*79.9(Molar mass of Bromide)

% of Ionic Bromide=ppm of Ionic Bromide/10000

[0187] The polymer contained 5% of Bromide by weight.

Example 4

[0188] The polymer P5 was prepared by copolymerizing acrylic acid, methacrylic acid and the monomer resulting from the quaternization of vinyl imidazole by hexylbromide:

[0189] Synthesis of copolymer poly(methacrylic acid-co-acrylic acid-co-(3-hexyl1-vinyl-1H-imidazolium-3-bromide, VImBr, synthesized as per the method described in Separation and Purification Technology 224 (2019) 388-396 in the present invention by conventional radical polymerization Initiator: α,α′-Azodiisobutyramidine dihydrochloride, (AAPH or V50, Sigma Aldrich); [0190] Monomers: MAA (Sigma Aldrich)=75 mol %, AA (Sigma Aldrich)=20 mol %, VImBr=5 mol %.

Stock Solution:

[0191] AA at 70 wt % in H.sub.2O, MAA at 60 wt % in H.sub.2O, VImBr at 70 wt % in H.sub.2O, V50 at 10 wt % in H.sub.2O

molar ratio: I/(VImBr+AA+MAA)=1.5 mol % [0192] Final solid content 35 wt %

[0193] In a 100 mL three necked round bottom flask equipped with magnetic stirrer, were introduced, at room temperature (22° C.), 0.22 g (5 wt % of stock solution) of acrylic acid, 0.36 g (5 wt % of stock solution) of 3-hexyl1-vinyl-1H-imidazolium-3-bromide (VImBr), 42 g of water and 0.87 g of V50 (solution in 10 wt % of water). The mixture was degassed by bubbling nitrogen in the bulk for 60 min. while the temperature in the solution increased up to 60° C. The remaining 95% of stock solution of AA and VImBr was mixed together and total 11.08 g mixture of both monomers was introduced for 3 hours into the reaction mixture. Simultaneously, MAA solution was started and performed over 4 hours (flow rate=0.0723 ml/min.). During the monomer addition, the solution became a gel and the reaction was stopped after complete addition of MAA.

[0194] Reaction mixture was precipitated in diethylether. Polymer was re-dissolved in methanol and re-precipitated in ethyl acetate. Unreacted monomer was removed by soxhlet in THF. Polymer was filtered and dried under at 60° C. vacuum for 6 hours and characterized by 1H NMR in D.sub.2O. The polymer was free from any residual unreacted monomer. Yield of the polymer was about 50%.

[0195] Average molecular weights were measured by Gel Permeation Chromatography (GPC) using Waters 515 equipped with column oven, Clarity software (GPC module), Shodex RI-71 Detector. The SEC system is running on two columns-Polymer Lab Aquagel-OH-40 & Polymer Lab Aquagel-OH-30 in series with Guard column, a flow rate of 1 mL/min/and with the following mobile phase 0.4M NaCl+0.05M Na.sub.2HPO.sub.4+0.003M NaN.sub.3-pH-9 (pH adjusted with few drops of 0.05M NaH.sub.2PO.sub.4). Dilute solution of polymer samples at 10 mg/ml were prepared in the mobile phase and then filtrated via a Millipore filter 0.2 μm before injecting to the system and 100 μL were injected in the mobile phase flow with a run time of 30 min. The measurement was carried out at 40° C. Ready Cal-Kit PEO/PEG (PSS-PEOkitr1) was used as the calibration standard. Results are: M.sub.n=81 kDa, M.sub.w=162 kDa, Polydispersity index=2.

[0196] Performances of Polymers P3, P4 and P5 were assessed with AA5754 H22 aluminum alloys coupons from FBCG (100 mm long, 25 mm wide, 3 mm thick) through Single Lap Shear (SLS) tests, before and after ageing in corrosive conditions. Coupons were prepared and assembled to form Single Lap assemblies as described above for Polymers P1 and P2.

[0197] Performances of polymer P2 were also assessed with the same batch of AA5754 H.sub.22 aluminum alloys coupons.

[0198] Process variations are reported Table 6, performance results Table 7-10.

TABLE-US-00006 TABLE 6 conditions of steps 1 and 2 Step 2: surface treatment Step 1: surface Polymer Test degreasing concentration no. & etching Polymer in the bath pH of the bath 2.1 NONE * NONE — — (control) (control) 2.2 same P2 1000 ppm 8.45 (native pH) 2.3 same P3 200 ppm 8.6 (native pH) 2.4 same P3 1000 ppm 8.0 (pH adjusted with caustic soda) 2.5 same P4 200 ppm 8.3 2.6 same P4 1000 ppm 7.7 (pH adjusted with caustic soda) 2.7 same P5 200 ppm 6.35 (pH adjusted with caustic soda) 2.8 same P5 1000 ppm 6.55 (pH adjusted with caustic soda) * coupons were wiped with acetone

TABLE-US-00007 TABLE 7 Maximum LOAD Maximum LOAD Before ageing (test I) After ageing (test II) maximum maximum load STD load STD Retention Test no. (N) (N) (N) (N) (%) 2.1 (control) 7432 393 1059 1138 14 2.2 9440 264 7881 215 83 2.3 9722 94 8002 156 82 2.4 9645 164 8191 133 85 2.5 9287 71 8147 111 88 2.6 9571 206 8046 175 84 2.7 9312 203 7604 514 82 2.8 9544 222 7922 66 83

TABLE-US-00008 TABLE 8 STRAIN at maximum load STRAIN at maximum load Before ageing (test I) After ageing (test II) strain STD strain STD Retention Test no. (MPa) (MPa) (MPa) (MPa) (%) 2.1(control) 24.0 1.3 3.4 3.7 14 2.2 29.6 0.5 24.8 0.6 84 2.3 31.0 0.2 25.4 0.9 82 2.4 29.7 0.5 25.7 0.5 87 2.5 29.5 0.2 26.0 0.7 88 2.6 30.0 0.5 25.7 0.7 86 2.7 29.4 0.8 24.6 1.6 84 2.8 29.8 1.0 25.3 0.6 85

TABLE-US-00009 TABLE 9 ENERGY at maximum load ENERGY at maximum load Before ageing (test I) After ageing (test II) Retention Test no. energy (J) STD (J) energy (J) STD (J) (%) 2.1 (control) 6.0 0.7 0.1 0.2 2 2.2 16.0 1.7 6.5 0.3 83 2.3 19.0 0.8 7.2 0.4 38 2.4 18.4 2.7 7.8 0.7 42 2.5 15.1 1.0 7.4 0.7 49 2.6 18.1 1.9 7.1 0.6 39 2.7 16.8 0.6 6.4 0.8 38 2.8 16.2 1.5 6.4 0.3 39

TABLE-US-00010 TABLE 10 FACIES after bond failure FACIES after failure *** Test no. Before ageing (test I) After ageing (test II) 2.1 (control) a a 2.2 c a/c 2.3 c a/c 2.4 c a/c 2.5 c a/c 2.6 c a/c 2.7 c a/c 2.8 c a/c c: cohesive fracture a: adhesive fracture a/c: adhesive and cohesive fracture