Protective coatings for aluminum alloy based on. hyperbranched 1,4-polytriazoles

Transcription

1 Protective coatings for aluminum alloy based on hyperbranched 1,4-polytriazoles Elaine Armelin a,b,*, Rory Whelan c, Yeimy Mabel Martínez-Triana, c Carlos Alemán a,b, M. G. Finn d and David Díaz Díaz c,e* a Departament d Enginyeria Química, EEBE, Universitat Polite cnica de Catalunya, C/ Eduard Maristany, 10-14, Ed. I2, 08019, Barcelona, Spain. b Center for Research in Nano-Engineering, Universitat Polite cnica de Catalunya, Campus Sud, Edifici C, C/Pasqual i Vila s/n, 08028, Barcelona, Spain. c Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, 93040, Regensburg, Germany. d School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA e IQAC-CSIC, Jordi Girona 18-26, 08034, Barcelona, Spain. *Corresponding authors: elaine.armelin@upc.edu and david. diaz@chemie.uni-regensburg.de S-0

2 RESULTS AND COMPLEMENTARY DISCUSSION 1,4-Polytriazoles film forming properties and morphology Regarding the product solid state, the thermal curing step was necessary in most cases, because otherwise he would have obtained polymers like glue. Thus, all solid film obtained were fully characterized from FTIR, SEM, DSC, TGA and DMTA analyses. Here we only describe the complementary data not included on the main text. Figure S1. Example of some polytriazoles films and powders obtained after three days at room temperature and post-cured at 110ºC for 1.5h. S-1

3 Figure S2. Non-isothermal FTIR spectra of sample 5A 3 5B 4 showing an example of azido group decrease (2090 cm -1 ) with subsequent formation of triazole ring ( cm -1 ). The spectra were acquired as a function of wavenumber-temperature at 5ºC/min from 30 to 200 ºC. A) B) Figure S3. Polytriazoles films 1A 21B 3: (A) fabricated as flexible thin films and (B) molded to a net rigid shape on right; transparent and flexible very thin film on left. All samples were detached from HDPE substrates. S-2

4 Thermal characterization Devitrification process commonly occurs in non-isothermal cure of crosslinking systems. During the cure of thermosetting resins, the glass transition temperature of the system (T g), changes from its initial value (T g0), namely that of the unreacted mixture, and increases with increasing degree of cure (α). In a non-isothermal cure experiment, the cure temperature increases at a constant rate. If this rate is sufficiently high, the cure temperature is always higher than the T g of the reacting system, so the crosslinking reaction will proceed to its limit (α =1), and the final glass transition temperature (T g ) will be that of the fully cured thermoset, which usually can be observed in the second heating scan (after fast cooling scan from the first heating scan). On the other hand, if the curing process takes place at a sufficiently slow heating rate, the T g of the reacting system can reach the instantaneous cure temperature, whereupon the system changes to a glassy state and vitrifies, analogous to the case of isothermal curing at sufficiently low cure temperatures. Then, the subsequent process of devitrification can occur with the systems when the continually increasing cure temperature, T c, again exceeds the T g of the vitrified system. This behavior was clearly observed for the samples 1A 21B 3 and 2A 22B 3, but does not occur to the other films prepared, as mentioned in the main text (see DSC curves inside). Additionally, in order to verify the influence of the cooper catalyst nature in the thermal properties of the 1,4-polytriazoles obtained from click-chemistry, the DSC was performed for both catalysts: 5A 35B 4-A, prepared from CuBF 4.4CH 3CN, and 5A 35B 4-B, prepared with CuPF 6.4CH 3CN (Figure 3, main text). Thermal responses were quite similar indicating that the copper catalyst nature does not influence the thermal behavior after the formation of the polymer thermoset chains. In order to check the results obtained with DSC, DMTA analysis was also employed. In a physical sense the storage modulus (E ) is related to the stiffness of the material and the loss modulus (E ) is reflected in the damping capacity of the material. In this respect the E peak Tg value is generally called onset temperature, originating from both the glassy region and the transition region. However, in general, the maximum loss modulus (tan δ) is the most S-3

5 appropriate value used for the glass transition temperature determination. In the Figure S4, it can be seen the DMA analysis for the sample 5A 35B 4. The T g for this polytriazole is evidenced by the broadened glass transition region in the loss tangent (tan δ) curve with two pronounced shoulder at about 110ºC and 130ºC. No rubbery state with a constant plateau was observed in storage modulus curve below 160ºC. Additionally, this thermoset polymer does not exhibit any soft transition behavior after ºC. Figure S4. Evolution of storage modulus and loss factor on heating 5A 35B 4 polytriazole cured film. S-4

6 The TGA curves and DTG temperature values (Figure S5) were discussed on the main text. Figure S5. TGA and DTG curves as a function of temperature for polytriazole films with filmforming properties. Wettability of polytriazoles coatings on AA2024 surface The hydrophobic property of one of the polytriazole coatings prepared here can be seen by the following videos available as supplementary information: Movie 1: AA2024_ hydrophilic surface.mov Movie 2: 1A2_1B3_hydrophobic surface.mov S-5

7 solution Characterization of corrosion resistance with increasing immersion time in NaCl Figure S6. Bode (left) and Nyquist (right) plots for AA2024 substrates covered with poly(1,4- disubstituted 1,2,3-triazoles) films, with increasing immersion time in NaCl 0.05 M. S-6

8 Figure S6. (Continuation ) S-7

9 Table S1. Data of EIS results obtained from the electrical equivalent circuit (EEC) for AA2024 panels protected with polytriazoles, after exposure to NaCl 0.05 M. AA hour 72 hours 7 days 20 days 30 days R s (R p CPE dl ) R s (R p CPE dl ) R s (R p CPE dl ) R s (R p CPE dl ) R s (CPE dl [R p W]) R s (Ω cm 2 ) R p (Ω cm 2 ) CPE dl (F cm -2 s n-1 ) n W (S cm -2 s 0.5 ) A 2 1B 3 R s (CPE c [R c CPE dl ]) R s (CPE c [R c CPE dl ]) R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (Ω cm 2 ) R c (Ω cm 2 ) CPE c (F cm -2 s n-1 ) n R ct (kω cm 2 ) CPE dl (F cm -2 s n-1 ) n A 2 2B 3 R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (Ω cm 2 ) R c (Ω cm 2 ) CPE c (F cm -2 s n-1 ) n S-8

10 R ct (kω cm 2 ) CPE dl (F cm -2 s n-1 ) n R dif (kω cm 2 ) CPE dif (F cm -2 s n-1 ) n A 3 5B 4 R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (Ω cm 2 ) No fitting R c (Ω cm 2 ) CPE c (F cm -2 s n-1 ) n R ct (kω cm 2 ) CPE dl (F cm -2 s n-1 ) n R dif (kω cm 2 ) CPE dif (F cm -2 s n-1 ) n A 3 4B 3 R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (Ω cm 2 ) No fitting R c (Ω cm 2 ) CPE c (F cm -2 s n-1 ) S-9

11 n R ct (kω cm 2 ) CPE dl (F cm -2 s n-1 ) n R dif (kω cm 2 ) CPE dif (F cm -2 s n-1 ) n A 3 5B 4 R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (R c CPE c )(R ct CPE dl ) R s (Ω cm 2 ) No fitting R c (Ω cm 2 ) CPE c (F cm -2 s n-1 ) n R ct (kω cm 2 ) CPE dl (F cm -2 s n-1 ) n R dif (kω cm 2 ) CPE dif (F cm -2 s n-1 ) n Note: R S : electrolyte resistance, R c : coating resistance, R ct : charge transfer resistance, CPE dl : constant phase element of double-layer interface, CPE c : constant phase element from coating layer; and W: Warburg impedance. S-10