PMID- 18351793
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20080611
LR  - 20080429
IS  - 0743-7463 (Print)
IS  - 0743-7463 (Linking)
VI  - 24
IP  - 9
DP  - 2008 May 6
TI  - A structural and corrosion study of triethoxysilyl functionalized POSS coatings 
      on AA 2024 alloy.
PG  - 5029-37
LID - 10.1021/la7037262 [doi]
AB  - A novel bifunctional polyhedral oligomeric silsesquioxane (POSS) based silane 
      precursor R(x)R'(y)(SiO(3/2))(8), (x + y = 8), bearing 
      3-(N-(3-triethoxysilylpropyl)ureido)propyl (ureasil - U) and isooctyl (IO) groups 
      (i.e., U(2)IO(6) POSS) was synthesized, and the corresponding coatings, prepared 
      under the acid hydrolysis conditions, were studied in order to assess their 
      corrosion inhibition of the AA 2024-T3 alloy. The U(2)IO(6) POSS precursor was 
      made in two steps: in the first, an appropriate stoichiometric (2:6) mixture of 
      3-aminopropyltriethoxysilane (AP(2)) and isooctyltrimethoxysilane (IO(6)) was 
      autoclaved under basic hydrolysis conditions giving AP(2)IO(6)(SiO(3/2))(8) 
      cubes, which were reacted in the second step with 
      3-isocyanatopropyltriethoxysilane (ICPTES), leading to the bis end-capped sol-gel 
      precursor U(2)IO(6) POSS having a cube-like structure. Coatings were made from 
      sols catalyzed with acidified water. IR and (29)Si NMR spectroscopic studies 
      combined with mass spectrometric measurements were employed to confirm the 
      cube-like structure of AP(2)IO(6) and U(2)IO(6) POSS. The structure and 
      morphology of the U(2)IO(6) POSS coatings were studied with the help of infrared 
      reflection-absorption (IR RA) spectroscopic measurements combined with XPS and 
      AFM measurements, providing information about the formation of partially 
      self-assembled coatings. The degree of corrosion inhibition was assessed from the 
      potentiodynamic measurements showing around 10 times smaller current densities 
      for the coatings only 30-40 nm thick. Ex situ IR RA spectroelectrochemical 
      measurements were performed by consecutive measurements of the IR RA spectra of 
      U(2)IO(6) POSS coatings which were chronocoulometrically charged at different 
      potentials. At potentials more positive than the corrosion potential (E(corr) 
      approximately -0.5 V), the amide I bands shifted, indicating the formation of new 
      urea-urea aggregations and associations, with the newly formed strong band at 
      1680-1690 cm(-1) suggesting the formation of amidonium ions. These results showed 
      that the urea groups represented the weakest part of the coatings due to their 
      tendency to protonation.
FAU - Jerman, Ivan
AU  - Jerman I
AD  - National Institute of Chemistry, Hajdrihova 19, and JoZef Stefan Institute, 
      Jamova 39, SI-1000 Ljubljana, Slovenia.
FAU - Vuk, Angela Surca
AU  - Vuk AS
FAU - Kozelj, Matjaz
AU  - Kozelj M
FAU - Orel, Boris
AU  - Orel B
FAU - Kovac, Janez
AU  - Kovac J
LA  - eng
PT  - Journal Article
DEP - 20080320
PL  - United States
TA  - Langmuir
JT  - Langmuir : the ACS journal of surfaces and colloids
JID - 9882736
EDAT- 2008/03/21 09:00
MHDA- 2008/03/21 09:01
CRDT- 2008/03/21 09:00
PHST- 2008/03/21 09:00 [pubmed]
PHST- 2008/03/21 09:01 [medline]
PHST- 2008/03/21 09:00 [entrez]
AID - 10.1021/la7037262 [doi]
PST - ppublish
SO  - Langmuir. 2008 May 6;24(9):5029-37. doi: 10.1021/la7037262. Epub 2008 Mar 20.