COPOLYMER AND ITS USE AS COATING

Abstract

A copolymer and its use as coating whereby the copolymer comprises a first monomer of the general formula (I)

##STR00001##

and a second monomer of the general formula (II)

##STR00002##

wherein Y is selected from the group consisting of CH.sub.2Z.sub.3, NHCOR.sub.5, CONHR.sub.6, OCOR.sub.7, COOR.sub.8 and OR.sub.9, and where Z.sub.1, Z.sub.2, and Z.sub.3 are selected from the group consisting of fluoro, chloro, bromo, iodo, hydroxyl, toluene-4-sulfonyloxy and methylsulfonyloxy. R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently from each other selected from the group consisting of linear or branched C.sub.1-C.sub.30 alkyl, a linear or branched C.sub.2-C.sub.30 alkenyl, a linear or branched C.sub.2-C.sub.30 alkynyl, sulfo, nitro, amino, hydroxy, oligo(C.sub.2 to C.sub.4-alkylene glycol), NHCOR.sub.5, CONHR.sub.6, OCOR.sub.7, COOR.sub.8 and OR. R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.9 are selected from the group consisting of a linear or branched C.sub.1-C.sub.30 alkyl, a linear or branched C.sub.2-C.sub.30 alkenyl and a linear or branched C.sub.2-C.sub.30 alkynyl.

Claims

1-14. (canceled)

15. A polymer comprising: phenylene methylene units obtained from a first monomer of the general formula (I) ##STR00008## wherein Z.sub.1 is selected from the group consisting of fluoro, chloro, bromo, iodo, hydroxyl, toluene-4-sulfonyloxy (OSO.sub.2C.sub.6H.sub.4CH.sub.3) and methylsulfonyloxy (OSO.sub.2CH.sub.3), and durene units obtained from a second monomer of the general formula (II) ##STR00009## wherein Z.sub.2 is selected from the group consisting of fluoro, chloro, bromo, iodo, hydroxyl, toluene-4-sulfonyloxy (OSO.sub.2C.sub.6H.sub.4CH.sub.3) and methylsulfonyloxy (OSO.sub.2CH.sub.3), Y is selected from the group consisting of CH.sub.2Z.sub.3, wherein Z.sub.3 is selected from the group consisting of fluoro, chloro, bromo, iodo, hydroxyl, toluene-4-sulfonyloxy (OSO.sub.2C.sub.6H.sub.4CH.sub.3) and methylsulfonyloxy (OSO.sub.2CH.sub.3); a linear or branched C.sub.1-C.sub.30 alkyl, a linear or branched C.sub.2-C.sub.30 alkenyl, a linear or branched C.sub.2-C.sub.30 alkynyl, sulfo (SO.sub.3H), nitro, amino, hydroxy, NHCOR.sub.5, CONHR.sub.6, OCOR.sub.7, COOR.sub.8 and OR.sub.9, wherein R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.9 are selected from the group consisting of a linear or branched C.sub.1-C.sub.30 alkyl, a linear or branched C.sub.2-C.sub.30 alkenyl and a linear or branched C.sub.2-C.sub.30 alkynyl; and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently from each other selected from the group consisting of linear or branched C.sub.1-C.sub.30 alkyl, a linear or branched C.sub.2-C.sub.30 alkenyl, a linear or branched C.sub.2-C.sub.30 alkynyl, sulfo (SO.sub.3H), nitro, amino, hydroxy, oligo(C.sub.2 to C.sub.4-alkylene glycol), NHCOR.sub.5, CONHR.sub.6, OCOR.sub.7, COOR.sub.8 and OR.sub.9, wherein R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.9 are selected from the group consisting of a linear or branched C.sub.1-C.sub.30 alkyl, a linear or branched C.sub.2-C.sub.30 alkenyl and a linear or branched C.sub.2-C.sub.30 alkynyl.

16. The polymer according to claim 15, wherein the second monomer has the general formula (IIa) ##STR00010## wherein Z.sub.2 is selected from the group consisting of fluoro, chloro, bromo, iodo, hydroxyl, toluene-4-sulfonyloxy (OSO.sub.2C.sub.6H.sub.4CH.sub.3) and methylsulfonyloxy (OSO.sub.2CH.sub.3), Z.sub.3 is selected from the group consisting of fluoro, chloro, bromo, iodo, hydroxyl, toluene-4-sulfonyloxy (OSO.sub.2C.sub.6H.sub.4CH.sub.3) and methylsulfonyloxy (OSO.sub.2CH.sub.3); and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently from each other selected from the group consisting of linear or branched C.sub.1-C.sub.30 alkyl, linear or branched C.sub.2-C.sub.30 alkenyl, linear or branched C.sub.2-C.sub.30 alkynyl, sulfo (SO.sub.3H), nitro, amino, hydroxy, oligo(C.sub.2 to C.sub.4-alkylene glycol), NHCOR.sub.5, CONHR.sub.6, OCOR.sub.7, COOR.sub.8 and OR.sub.9, wherein R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.9 are selected from the group consisting of a linear or branched C.sub.1-C.sub.30 alkyl, a linear or branched C.sub.2-C.sub.30 alkenyl and a linear or branched C.sub.2-C.sub.30 alkynyl.

17. The polymer according to claim 15, wherein Z.sub.2 and Z.sub.3 are the same.

18. The polymer according to claim 15, wherein Z.sub.1, Z.sub.2 and Z.sub.3 are the same.

19. The polymer according to claim 17 or 18, wherein Z.sub.1, Z.sub.2 and Z.sub.3 are chloro.

20. The polymer according to claim 15, wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are the same.

21. The polymer according to claim 20, wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are methyl.

22. The polymer according to claim 15, comprising further durene units obtained from one or more monomers of the general formula (III) ##STR00011## wherein Z.sub.2 is selected from the group consisting of fluoro, chloro, bromo, iodo, hydroxyl, toluene-4-sulfonyloxy (OSO.sub.2C.sub.6H.sub.4CH.sub.3) and methylsulfonyloxy (OSO.sub.2CH.sub.3), Y is selected from the group consisting of CH.sub.2Z.sub.3, wherein Z.sub.3 is selected from the group consisting of fluoro, chloro, bromo, iodo, hydroxyl, toluene-4-sulfonyloxy (OSO.sub.2C.sub.6H.sub.4CH.sub.3) and methylsulfonyloxy (OSO.sub.2CH.sub.3); a linear or branched C.sub.1-C.sub.30 alkyl, a linear or branched C.sub.2-C.sub.30 alkenyl, a linear or branched C.sub.2-C.sub.30 alkynyl, sulfo (SO.sub.3H), nitro, amino, hydroxy, NHCOR.sub.5, CONHR.sub.6, OCOR.sub.7, COOR.sub.8 and OR.sub.9, wherein R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.9 are selected from the group consisting of a linear or branched C.sub.1-C.sub.30 alkyl, a linear or branched C.sub.2-C.sub.30 alkenyl and a linear or branched C.sub.2-C.sub.30 alkynyl; and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently from each other selected from the group consisting of a linear or branched C.sub.1-C.sub.30 alkyl, a linear or branched C.sub.2-C.sub.30 alkenyl, a linear or branched C.sub.2-C.sub.30 alkynyl, sulfo (SO.sub.3H), nitro, amino, hydroxy, oligo(C.sub.2 to C.sub.4-alkylene glycol), NHCOR.sub.5, CONHR.sub.6, OCOR.sub.7, COOR.sub.8 and OR.sub.9, wherein R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.9 are selected from the group consisting of a linear or branched C.sub.1-C.sub.30 alkyl, a linear or branched C.sub.2-C.sub.30 alkenyl and a linear or branched C.sub.2-C.sub.30 alkynyl, and wherein the monomer of the general formula (III) is different from the monomer of the general formula (II).

23. The polymer according to claim 15, wherein in the compound of formula II at least one of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 is selected from the group consisting of a linear or branched C.sub.8-C.sub.30 alkyl, a linear or branched C.sub.8-C.sub.30 alkenyl, a linear or branched C.sub.8-C.sub.30 alkynyl and OR.sub.9, wherein R.sub.9 is selected from the group consisting of a linear or branched C.sub.8-C.sub.30 alkyl, a linear or branched C.sub.8-C.sub.30 alkenyl and a linear or branched C.sub.8-C.sub.30 alkynyl.

24. The polymer according to claim 16, wherein in the monomer of formula Ila at least one of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 is selected from the group consisting of a linear or branched C.sub.8-C.sub.30 alkyl, a linear or branched C.sub.8-C.sub.30 alkenyl, a linear or branched C.sub.8-C.sub.30 alkynyl and OR.sub.9, wherein R.sub.9 is selected from the group consisting of a linear or branched C.sub.8-C.sub.30 alkyl, a linear or branched C.sub.8-C.sub.30 alkenyl and a linear or branched C.sub.8-C.sub.30 alkynyl.

25. The polymer according to claim 15, wherein the polymer comprises 0.01 to 5% (mol/mol) of durene units obtained from the second monomer of the general formula (II).

26. A method for preparing a polymer according to claim 15, wherein the monomer of the general formula (I) and the monomer of the general formula (II) are polymerized in the presence of a Lewis acid catalyst.

27. The method according to claim 26, wherein the catalyst is selected from the group consisting of bismuth(III)-based catalyst, molybdenum-based catalyst and tungsten-based catalyst, preferably selected from the group consisting of WCl.sub.4(CNMe).sub.2, WCl.sub.4(THF).sub.2, WBr.sub.2(CO).sub.3(dme) and MoI.sub.2(CO).sub.3(MeCN).sub.2.

28. The method according to claim 26, wherein the polymerization of the monomer of the general formula (I) is carried out in the presence of the catalyst during the whole polymerization, and the monomer of the general formula (II) is added not before at least 40% by weight of the monomer of the general formula (I) have reacted.

29. A method of protecting a substrate comprising applying to the substrate a coating comprising the polymer according to claim 15.

30. A powder comprising the polymer according to claim 15.

31. A paint comprising the polymer according to claim 15.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0058] FIG. 1a shows the progress of monomer conversion in presence of WCl.sub.4(THF).sub.2 and operative temperature as function of the reaction time.

[0059] FIG. 1b shows gel permeation chromatograms of aliquots taken over the reaction and reveals the evolution of a trimodal molar mass distribution. Symbols of the curve coincide with the symbols of monomer conversion in FIG. 1a.

[0060] FIG. 2 shows gel permeation chromatograms of poly(phenylene methylene) syntheses with different catalysts.

[0061] FIG. 3 shows the comparison of .sup.13C NMR signals of PPM synthesized with each catalyst. The peaks are assigned to the respective substitution pattern of the phenylene rings.

[0062] FIG. 4a shows the progress of the monomer conversion and operative temperature in presence of BCMD as function of the reaction time.

[0063] FIG. 4b shows gel permeation chromatograms of aliquots taken over the reaction and reveals the evolution of a trimodal molar mass distribution. Symbols of the curve coincide with the symbols of monomer conversion in FIG. 4a.

[0064] FIG. 5 shows gel permeation chromatograms of the low molar mass fraction (Flow, squares), and high molar mass (high, circles).

[0065] FIG. 6 shows a comparison of the normalized .sup.13C NMR signals of PPM copolymer (squares) and PPM homo-polymer (circles).

[0066] FIG. 7 shows the accelerated cyclic electrochemical technique (ACET) results for 30 m thick coating PPM containing octyloxy side chain according to the prior art.

[0067] FIG. 8 shows the accelerated cyclic electrochemical technique (ACET) results for pre-damaged 30 m thick coating PPM containing octyloxy side chain according to the prior art.

[0068] FIG. 9 shows the accelerated cyclic electrochemical technique (ACET) results for 30 m thick coating with a copolymer according to the present invention.

[0069] FIG. 10 shows the accelerated cyclic electrochemical technique (ACET) results for pre-damaged 30 m thick coating with a copolymer according to the present invention.

DETAILED DESCRIPTION

Examples

Synthesis of Poly(Phenylene Methylene) Catalyzed by Complexes Based on W and Mo

[0070] The polymerizations of benzyl chloride were carried out with a monomer to catalyst ratio of about 0.1% mol/mol for each catalyst. Although the polymerization conditions are essentially based on procedures already reported in the literature from Brandle et al. (Journal of Polymer Science, 2018, 56, 309ff) the reaction temperature had to be modified for the catalytic systems applied here, independently on time constraints, from room temperature to 80 C., 120 C., 160 C. and 180 C. in order to mitigate the viscosity increase and allow an efficient mixing over the course of the reaction. Below the example of the polymerization catalysed by [WCl.sub.4(THF).sub.2] is provided. The stabilizer propylene oxide present in the starting material was removed from benzyl chloride under reduced pressure (10.sup.2 bar) overnight. In a 50 mL three neck flask, 20 g of benzyl chloride (20.8 mL, 0.16 mol) were added to the solid catalyst [WCl.sub.4(THF).sub.2](70 mg, 0.1 mmol) under nitrogen atmosphere keeping a constant gas flow of 15 mL min.sup.1. The crude of reaction was then let under mechanical stirring for 3 h in order to assure a good mixing between the catalyst and the monomer. Over the course of reaction the temperature was risen from 25 C. to 180 C. in order to enable mixing upon the increase of viscosity due to the molar mass increase. As the reaction was complete, the molten polymer was allowed to cool down to room temperature. The product was purified by dissolving the polymer in 30 mL of chloroform and then pouring the solution into 600 mL of methanol. The suspension was let at vigorous stirring for 3 h. The obtained PPM powder was then filtered over cellulose filter and the polymer powder was dried under vacuum (10.sup.2 bar) over night. 6.3 g of pale-yellow polymer were obtained (yield 66%). .sup.1H NMR (300 MHz, CDCl.sub.3, in ppm): 3.79 (broad, 2H), 7 (broad, 4H). GPC (THF). Molar masses are given in Table 1 and the .sup.13C NMR spectrum is shown below.

[0071] The synthesis with the catalysts [WCl.sub.4(MeCN).sub.2], [WBr.sub.2(CO).sub.3(dme)], [MoI.sub.2(CO).sub.3(MeCN).sub.2] was performed analogously. The yields of purified PPM polymers amounted to 68%-77% and are indicated in Table 1 together with the molar masses.

TABLE-US-00001 TABLE 1 Number average molar mass (M.sub.n), weight average molar mass (M.sub.w), polydispersity index (PDI) and yield of reaction of the polymers synthesized with the W- and Mo-based catalysts. M.sub.n M.sub.w Yield of Catalyst (g mol.sup.1) (g mol.sup.1) PDI reaction [WCl.sub.4(MeCN).sub.2] 3,118 7,013 2.2 68% [WBr.sub.2(CO).sub.3(dme)] 3,325 13,170 3.9 72% [Mol.sub.2(CO).sub.3(MeCN).sub.2] 4,538 11,480 2.5 77% [WCl.sub.4(THF).sub.2] 4,090 63760 15.6 69%
Synthesis of a Poly(Phenylene Methylene) Based Copolymer Catalyzed by WCl.sub.4(THF).sub.2

[0072] PPM with durene units was synthesized in presence of 0.5% mol/mol 1,4-bis(chloromethyl)-2,3,5,6-tetramethylbenzene (3.6-bis(chloromethyl)durene, BCMD) as described above with [W.sub.2Cl.sub.4(THF).sub.2](75 mg, 0.16 mmol) as catalyst, however, by adding 172 mg of BCMD (7.4.10.sup.1 mmol) to 17 mL benzyl chloride (148 mmol). The evolution of color during the reaction was as follows: clear yellow brown for the first minute, black at 80 C., blue at 120 C., and dark green at 160 C. After sample work-up as described above for PPM, a quantity of 6.63 g (82%) of green bluish product was obtained. .sup.1H NMR (300 MHz, CDCl.sub.3, in ppm): 2.5 (s, 0.12H, CH.sub.3) 3.71 (br, 2H, CH.sub.2), 7.19 (br, 4H, Ar); GPC (CHCl.sub.3): M.sub.n=3,400 g mol.sup.1, weight average molar mass (M.sub.w)=211,977 g mol.sup.1, M.sub.w/M.sub.n=55.4; DSC (T.sub.g): 52.0 C.

Fractionation by Phase Separation

[0073] The copolymer (1 g) (M.sub.n=3,317 g mol.sup.1, M.sub.w=183,600 g mol.sup.1) and 2-butanone (23 mL) were stirred vigorously for 2 h after which the suspension separated into a clear upper phase with the low molar mass polymer (F.sub.low) and a turbid oily phase with high molar mass polymer (F.sub.medium). The upper and the lower phases were separated, and the solvent was removed by a rotary evaporator, and then dissolved again in 5 mL of chloroform. The solutions were precipitated in 200 mL of methanol under stirring, and the solids were filtered and dried (as described above), to give 0.452 g (fractionation yield 45%) of F.sub.medium (M.sub.n=33,520 g mol.sup.1, M.sub.w=322,000 g mol.sup.1) (when the fractionation procedure was repeated twice, it was not possible to isolate higher molar mass fractions). Thereafter, 50 mg of F.sub.medium were further washed with 5 mL of a mixture of chloroform/2-butanone (1:1 by volume) in order to remove lower molar mass fractions and to provide the polymer fraction F.sub.high (23 mg, fractionation yield 46%) (M.sub.n=205,300 g mol.sup.1, M.sub.w=777,900 g mol.sup.1).

Characterization

[0074] .sup.1H NMR and .sup.13C NMR spectra were recorded on a Bruker AV300 MHz spectrometer using CDCl.sub.3 as solvent. The multiplicity of peaks is indicated as (bs) for broad signals, (s) singlet, (d) doublet, (t) triplet and (m) multiplet. The monomer conversion was evaluated by withdrawing aliquots of the reaction mixtures during the reaction to be analyzed by .sup.1H NMR spectroscopy according to the literature. The molar masses were investigated by gel permeation chromatography (GPC) using a Viscotek GPC system using tetrahydrofuran (THF) as eluent. The GPC module comprised a pump and degasser system (GPCmax VE2001; 1.0 mL min.sup.1 flow rate), Viscotek 302 TDA as detector and two columns for the analysis of different molar masses (2PLGel Mix-B; dimensions 7.5 mm300 mm). The thermal characterization was performed with a TGA/DSC 3+ module (Mettler Toledo). The thermal transitions were investigated from 25 C. to 360 C. under nitrogen flush (50 mL min.sup.1), increasing the temperature with a rate of 10 C. min.sup.1. The onset of decomposition was evaluated in a temperature range of 25 C. to 900 C. under air flush (50 mL min.sup.1) with a temperature increasing rate of 10 C. min.sup.1.

Evaluation of the Catalytic Activity in Homo-Polymerization of Benzyl Chloride

[0075] The screening of [WCl.sub.4(MeCN).sub.2], [WCl.sub.4(THF).sub.2], [WBr.sub.2(CO).sub.3(dme)] and [MoI.sub.2(CO).sub.3(MeCN).sub.2] as catalysts for the bulk polymerization of benzyl chloride was performed keeping the same molar ratio catalyst/monomer (0.1% mol/mol) for all the compounds. Before the temperature increase and start of the reactions, the catalysts were let to dissolve in benzyl chloride at room temperature. Due to the different solubility of each catalyst in benzyl chloride, dissolution times in the range of minutes were observed for [MoI.sub.2(CO).sub.3(MeCN).sub.2] and [WBr.sub.2(CO).sub.3(dme)], while for W(IV)-based catalyst 4 h were needed. The temperature of the reaction was then adjusted over the course of polymerization to avoid mixing problems arising by the increase of viscosity (i.e. the Weissenberg effect). The temperature required for polymerization and the consequent monomer conversion strongly depended on the compound. In particular, the polymerization in presence of [MoI.sub.2(CO).sub.3(MeCN).sub.2] was triggered already at 80 C., reaching quickly (10 min) a monomer conversion of about 90%. When [WCl.sub.4(MeCN).sub.2] was employed, the monomer conversion raised significantly between 80 C. to 120 C. settling above 80% after 5 h at this temperature. Previously reported W(II)-based catalysts also showed catalytic activity below 120 C., By contrast, polymerization catalyzed by [WCl.sub.4(THF).sub.2] or [WBr.sub.2(CO).sub.3(dme)] were initiated only at temperatures at or above 150 C.

[0076] The monomer conversion of the polymerization catalyzed by [WBr.sub.2(CO).sub.3(dme)] reached 100% after 5 h at 150 C. Notably, at this temperature no striking increase of viscosity was observed, probably due to the low molar mass of the obtained polymer. On the other hand, the monomer conversion at 150 C. of the polymerization catalyzed by [WCl.sub.4(THF).sub.2] settled below 10% after 17 h. The rise of the temperature to 180 C. was crucial in order to increase the monomer conversion and complete the reaction as evident from FIG. 1a which shows the monomer conversion obtained from .sup.1H NMR spectra of aliquots removed from the reaction mixture. FIG. 1b displays the GPC chromatograms of the aliquots sampled after various monomer conversions. Those chromatograms disclose that upon triggering of the reaction at 150 C. at the monomer conversion of 2%, a bimodal molar mass distribution with a peak at 15.4 min corresponding to a molar mass between 4,500 g mol.sup.1 and 63,000 g mol.sup.1 and a smaller peak at 16.6 min (below 4,480 g mol.sup.1) emerged. After 17 h at this temperature, the two peaks shifted to lower retention times, 14.3 min and 15.4 min, both in the molar mass range between 4,000 g mol.sup.1 and 500,000 g mol.sup.1. Those chromatograms showed a tail after 17 min corresponding to monomer and oligomers still present in the reaction batch at this degree of monomer conversion. As the temperature was increased up to 180 C., the oligomer fractions grew faster with respect to the high molar mass fraction reflecting a rise of the peak at 16.3 min and thus a pronounced decrease of M.sub.n as the monomer conversion increased (FIG. 1b). The opposite was observed for other tungsten-based catalysts.

[0077] The presence of high molar masses at low monomer conversions indicates that in presence of [WCl.sub.4(THF).sub.2] a chain-growth-like mechanism is involved (a chain-growth-like processes was also reported for other tungsten-based catalysts). By contrast, such an effect was not observed in the polymerizations using [WCl.sub.4(MeCN).sub.2], [WBr.sub.2(CO).sub.3(dme)] and [MoI.sub.2(CO).sub.3(MeCN).sub.2].

[0078] After isolation of the polymers by dissolution and subsequent precipitation, the polymers resulting from [WCl.sub.4(MeCN).sub.2], [WBr.sub.2(CO).sub.3(dme)] and [MoI.sub.2(CO).sub.3(MeCN).sub.2] catalysts (FIG. 2) exhibited a monomodal molar mass distribution with M.sub.n between 3,100 g mol.sup.1 and 4,500 g mol.sup.1 and M.sub.w between 7000 g mol.sup. and 13,000 g mol.sup. (Table 1), which lies in the conventional range of PPM (see Introduction). However, the PPM obtained using [WCl.sub.4(THF).sub.2] revealed a bimodal molar mass distribution (Error! Reference source not found.), presenting a M.sub.n of 4,090 g mol.sup.1 in coherence with the other catalysts, but a higher M.sub.w (63,760 g mol.sup.1) and thus much higher PDI (15.6) (Table 1).

TABLE-US-00002 TABLE 2 Number average molar mass (M.sub.n), weight average molar mass (M.sub.w), polydispersity index (PDI) and yield of reaction of the polymers synthesized with the W- and Mo-based catalysts. M.sub.n M.sub.w Yield of Catalyst (g mol.sup.1) (g mol.sup.1) PDI reaction [WCl.sub.4(MeCN).sub.2] 3,118 7,013 2.2 68% [WBr.sub.2(CO).sub.3(dme)] 3,325 13,170 3.9 72% [Mol.sub.2(CO).sub.3(MeCN).sub.2] 4,538 11,480 2.5 77% [WCl.sub.4(THF).sub.2] 4,090 63760 15.6 69%

[0079] Among the investigated catalysts, the Mo(II)-based complex and [WCl.sub.4(THF).sub.2] led to an M.sub.n which was 25%-30% above that of the other tungsten catalysts. However, we consider this and the higher M.sub.w obtained with [WCl.sub.4(THF).sub.2] as a specific effect of the applied compounds and not as a general property of molybdenum- or W(IV)-based catalysts, all the more as the catalysts have different operation temperatures.

[0080] The .sup.13C NMR spectra of purified PPMs correspond to those of PPM reported with other catalysts. The signals in the range of 33 ppm-44 ppm (FIG. 3) are attributed to the substitution patterns along the PPM backbone, as reported previously (the .sup.13C NMR signals in the aromatic region between 125 ppm and 145 ppm are shown in the Supporting Information (SI. 1)). The .sup.1H NMR spectra (Supporting Information (SI.2)) show the broad peak at 3.7 ppm of the methylene region and the broad peak between 6.5 and 7.25 ppm of the phenylene group for each polymer, as also reported for PPM obtained using SnCl.sub.4 or W(II)-based catalysts.

[0081] The obtained polymers were investigated with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). All the polymers showed high thermal stability presenting an onset of decomposition temperatures above 400 C. Moreover, glass transition temperatures in the range of 58 C.-63 C. were found and no further 1.sup.st order thermal transitions were detected. Thus, the thermal properties of the obtained polymers are in agreement with the data reported for PPM obtained by other catalysts such as SnCl.sub.4 or W(II)-based complexes (T.sub.g 60 C.-65 C., onset of decomposition above 400 C.).

Effect of , Bis-Chloromethyl Durene on Connectivity

[0082] Based on the results obtained with the above catalysts, [WCl.sub.4(THF).sub.2] was selected in order to enhance the molar mass with the bifunctional branching agent BCMD as co-monomer, since [WCl.sub.4(THF).sub.2] provided the highest M.sub.w. As evident from FIG. 4a, the presence of BCMD (0.5% mol/mol) did not affect the initiation temperature of the polymerization (no reaction below 150 C.) but as the temperature of 150 C. was reached, the reaction became faster than in the homopolymerization. While in case of the homopolymerization the monomer conversion did not grow above 10% at 150 C., at the same temperature the monomer conversion in presence of BCMD reached 70%, accompanied with an increase of viscosity reflected in the observation of the Weissenberg effect. Therefore, to ensure a correct mixing in the polymerization batch the temperature was raised to 180 C. until complete monomer conversion. The chromatograms displayed in FIG. 4b show again a multimodal distribution of the molar masses emerging over the course of polymerization, with a general shift of the peaks to higher molar masses. Notably, differently to the homopolymerization, in presence of the branching agent the intensity of the high molar mass peak at 12 min (M.sub.n 914,800 g mol.sup.1) increased with increasing monomer conversion. Although the overall M.sub.n (3,400 g mol.sup.1) did not change strikingly, M. (212,000 g mol.sup.1) increased by a factor of 4 with respect to the homopolymerization. The product with BCMD was isolated by dissolution and subsequent precipitation as the corresponding homopolymer described above. Compared to the in-situ product, the isolated product possessed essentially the same M.sub.n (3,400 g mol.sup.1) but a slightly lower M.sub.w (187,900 g mol-). On the other hand, the M.sub.w was 3.8 times higher than that of the product without BCMD, revealing a higher fraction of high molar mass product obtained with BCMD. In order to separate the highest molar mass fractions, the obtained polymer was dissolved in 2-butanone resulting in a spontaneous separation corresponding to a lower molar mass fraction (F.sub.low) and a higher molar mass fraction (F.sub.medium), as reported elsewhere for fractionation of PPM. Moreover, further extraction of lower mass polymers in the F.sub.medium fraction was performed with a chloroform:2-butanone 1:1 (by volume) mixture to yield the fraction F.sub.high The results of fractionation are shown in Table 3. The M.sub.n of F.sub.medium (33,520 g mol.sup.1) is an order of magnitude above the value before fractionation and also of the values commonly obtained for PPM (see Introduction). The M.sub.n of the fraction F.sub.high (205,300 g mol.sup.1) even exceeds the highest molar mass of a PPM isolated so far (167,900 g mol.sup.1, also obtained by fractionation). The GPC diagram (FIG. 5) also reveals that the lowest molar masses (F.sub.low) were completely separated from the fraction with the highest molar mass (F.sub.high). It is also evident from FIG. 5 that F.sub.high consists of a bimodal molar mass distribution with two peaks representing molar masses of 872,000 g mol.sup.1 and 122,200 g mol.sup.1 (12 min and 13.5 min in the GPC diagram). However, our attempts to separate these two fractions to obtain a fraction with ultrahigh molar mass failed.

TABLE-US-00003 TABLE 3 Number average molar mass (M.sub.n), weight average molar mass (M.sub.w), polydispersity index (PDI), yield of fractionation and polymer fraction composition resulting from polymerization of benzyl chloride with 0.5% mol/mol BCMD catalyzed by [WCl.sub.4(THF).sub.2], yielding the fraction F.sub.low, F.sub.medium, F.sub.high (see text). Yield of Yield of Mn M.sub.w first frac- second frac- Fraction (g mol1) (g mol.sup.1) PDI tionation (%) tionation (%) F.sub.low 1,821 3,794 2.1 55 F.sub.medium 33,520 322,100 9.6 45 54 F.sub.high 205,300 772,900 3.7 46

[0083] The main difference between the products obtained with and without BCMD in .sup.13C NMR spectra was the rise of a peak at 16.5 ppm (FIG. 6) corresponding to the signal of methyl groups belonging to the durene unit, confirming that durene units were incorporated in the polymer chains. The .sup.13C NMR spectra in the methylene region (30 ppm-42 ppm) showed slight differences of the substitution patterns between the copolymer and the homopolymer (FIG. 6). Essentially, the relative intensity of the ortho-ortho substitution pattern increased somewhat. In .sup.1H NMR spectra the distinctive signals of PPM emerged (broad peak at 3.7 ppm and in the range of 6.8-7.2 ppm) and a peak at 2.5 ppm which is attributed to the methyl groups in the durene framework. The integration of the NMR signals revealed a concentration of durene units of about 0.4% mol/mol with respect to phenylene units, which is slightly lower than in the initial reaction mixture. This could be in the context of the work-up procedure of the sample. The thermal properties of PPM-D (T.sub.g 65 C., onset of decomposition at 410 C.) were similar to those of PPM.

Comparison of 4-Octyloxy Copolymer and Tetramethyl Copolymers

[0084] The comparison between coatings made by PPM co-polymers containing 4-octyloxy side chains and coating of PPM copolymer containing BCMD was performed according to the rule ISO 17463:2014 (procedure reported below). However, the thicknesses of the two kind of coatings tested were not equivalent as the copolymer disclose from D'Elia et al. is only processable by hot-pressing (only thicker films can be obtained). Therefore, the thickness of the coatings of the prior art are 30 m while those of the novelty obtained by spray coating are only 20 m. Those tests revealed for coating containing octyloxy side chains a |Z|.sub.0.01 Hz of 10.sup.7 cm.sup.2 during the preliminary EIS cycle. Over the following ACET cycles an increase of |Z|.sub.0.01 Hz is observe settling to values higher than 10.sup.8 cm.sup.2 (FIG. 7). Despite the good corrosion protection ability of this coating, the increase of |Z|.sub.0.01 Hz after the preliminary EIS would be attributed to the progressive saturation of the porosities on the coating surface reflecting the presence of inhomogeneities within the polymeric film. The criticalities of this kind of coating became predominant when a pre-damaged surface is exposed to the ACET test (FIG. 8). Although after the damaging the coating presents a good anticorrosion protection (values of |Z|.sub.0.01 Hz included between 10.sup.7 and 10.sup.8 cm.sup.2 in the first two ACET cycles) after the third cycle the coating fails (|Z|.sub.0.01 Hz about 10.sup.4 cm.sup.2) with consequent development of corrosion products. The ACET test carried out on coating surface made by PPM copolymer obtained using BCMD displayed high corrosion protection (despite being thinner than the previous one) and high surface homogeneity reflected by |Z|.sub.0.01 Hz well above 10.sup.8 cm.sup.2 (FIG. 9). As reported in FIG. 10 the ACET performed on the pre-damaged surface revealed that this coating possesses a high protection ability even after damage. This would be attributed to a better self-healing.

Preparation of Coatings

[0085] Sheets of 12 cm in length, 3 cm in width and 4 mm in thickness of high strength aluminum alloy AA2024 (4.3%-4.5% copper, 1.3%-1.5% magnesium, 0.5%-0.6% manganese and less than 0.5% of other elements) were provided by Aviometal s.p.a (Varese, Italy) and used as substrate. Samples of 4 cm in length were cut and subsequently polished with abrasive papers of 300, 500, 800, 1200, and 4000 grit. Immediately after polishing, the samples were cleaned by immersion in ethanol in an ultrasonic bath (Banderlin, Berlin, Germany) for 5 min. Then AA2024 samples were removed from the ethanol bath and the residual alcohol at the surface was evaporated by means of a flush of nitrogen.

[0086] A layer of benzyltriethoxysilane was applied by spin coating (3500 rpm, 30 s) on freshly cleaned AA2024 samples and subsequently heated up to 100 C. for 1 min, whereupon condensation of benzyltriethoxysilane to respective polysiloxanes proceeded.

[0087] Coatings of the copolymers were manufactured by pressing polymer powders onto these silane-pretreated AA2024 specimen, using polyetheretherketone (PEEK) foil to separate the PPM-based polymers from the pressing instrument. Pressing was performed for octyloxy copolymersprior art(13.4% mol/mol) at a temperature of 120 C. for 30 s. The thickness was between 30 m and 50 m. Coatings appeared very uniform and homogeneous although no rheological additive was added. BCMD copolymer coatingnoveltywas obtained dissolving BCMD copolymer in chloroform to obtain a 0.37 g/mL solution. Then the solution was formulated with p-xylene with a ratio 3.9 mL/mL (p-xylene/polymer solution). The formulation was applied on a non-pretreated AA2024 surface at 120 C. via spray coating with a pressure of 0.5 bar.

Electrochemical Characterization of Coated AA2024

[0088] The anticorrosion ability of coating was studied by means of electrochemistry techniques, carrying out tests on AA2024 samples coated with the two copolymers (octyloxyprior art13.4% mol/mol and BCMDnovelty0.4% mol/mol).

[0089] Electrochemical corrosion tests were conducted in a naturally aerated near-neutral simulated marine environment prepared by dissolving 0.6 mol L.sup.1 sodium chloride (99.0%, Sigma-Aldrich) in MilliQ water. The pH value was adjusted to 6.70.1 by adding few drops of 0.2 mol L.sup.1 sodium hydroxide solution to the stock solutions. All the experiments, if not otherwise stated, were carried out at ambient temperature (243 C., with a variation lower than 2 C. during each single run). In all cases, the operative temperature was below the glass transition temperature of the copolymer according to the present invention.

[0090] The apparatus used for the measurements consisted of a glass cell with a hole (1 cm in diameter) in the middle of the flat bottom part which assures the contact between the coated metallic plate (working electrode, exposed area 0.78 cm.sup.2) and the working solution (0.6 M NaCl). The sealing was guaranteed by a bi-adhesive layer (a2 Soluzioni Adesive, Italy) pressed between the sample and the bottom of the cell. The electrochemical setup also included a platinum coil as counter electrode and an aqueous saturated calomel electrode as reference one (E.sub.SCE=0.242 V vs. SHE). The latter was inserted into a glass double bridge (filled with the same working solution) ending with a Luggin capillary aimed to minimize the ohmic drop between working and reference electrode. No instrumental compensation of the residual ohmic drop was performed.

[0091] The electrochemical characterization included both potentiodynamic and potentiostatic methods. The former consisted of an anodic polarization scan, sweeping the potential from OCP to 2.5 V vs. SCE, at a scan rate of 10 mV min.sup.1 (each run lasting ca. 5.5 h). A limit current density of 4 mA cm.sup.2 was imposed, thereafter the scan was automatically aborted independently by the achievement of the final potential. The second characterization implies the application of a constant potential to the metallic sample and the recording of the current flow between working and counter electrode. In our experiments, an oxidizing potential of 0 V vs. SCE was applied for 24 h.

[0092] Potentiodynamic and potentiostatic curves were recorded after an initial delay time of 600 s for assuring the equilibration of the system at OCP. Some potentiodynamic curves were recorded also at a fixed temperature of 35 C., just above the glass transition temperature of the copolymer according to the present invention. For these experiments, a suitable cell surrounded by a jacket filled by a flux of water controlled by a thermostat (Haake CH Fisons coupled to a Haake F3 Fision) was adopted.

[0093] For accelerated scanning electrochemical technique (ACET), after a conditioning of 10 minutes at the open circuit potential (OCP) a preliminary control electrochemical impedance spectroscopy (EIS) is performed. A following sequence of polarization-relaxation-EIS was repeated at least six times, one after the other, according to the international standard ISO 17463:2014. The EIS analyses were conducted in the frequency range from 100 kHz to 0.01 Hz using a sinusoidal voltage of 10 mV as amplitude at the open circuit potential (OCP). The following cathodic polarization step was performed at 2 V vs. SCE for 20 minutes; the relaxation process at the OCP lasted 3 hours; then a new EIS step was carried out using the same mentioned parameters. The intrinsic self-healing and the anticorrosion performance of PPM copolymer coatings were also investigated by using accelerated cyclic electrochemical technique, applying an artificial circular scratch (diameter of the hole 0.52 mm, depth corresponding to the coating thickness) during the already mentioned conditioning time. The evaluation of impedance modulus at the lowest frequency 0.01 Hz (|Z|.sub.0.01 Hz) provides the impedance of the coating. High values of |Z|.sub.0.01 Hz (>10.sup.7 cm.sup.2) reflect high corrosion protection.