In order to broaden the applications of bio-epoxy resins in high performance sector, an understanding of thermal behavior of these environmentally-friendly biopolymers is essential. This study investigates the thermal degradation mechanism of a bio-epoxy resin (E-epoxy) derived from bark extractives in comparison with a petroleum-based epoxy resin. The thermogravimetric analysis (TGA) results show that the activation energy of E-epoxy varied significantly with the extent of degradation indicating a multistage degradation mechanism involving a variety of compounds. According to Fourier transform infrared spectroscopy (FTIR) analysis, the dehydration and crosslinking reactions occurred at low temperatures, while the Claisen chain rearrangement and chain-scission reactions dominated at high temperatures. The pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) results show that a significant amount of methyl abieta-8,11,13-trien-18-oate, diethyl phthalate, 2,2'-isopropylidenebis(3,5-dimethylbenzofuran), and epimanool were detected in the bio-epoxy resins. The newly proposed degradation mechanism of bio-epoxy resins based on structural illustration through FTIR and Py-GC/MS can provide guidance for design of high performance bio-based epoxies. (C) 2015 Elsevier B.V. All rights reserved.

This study presents the preparation and fabrication of a series of silane-grafted polymethylsilsesquioxane (SGPMSQ) with a controllable structure and molecular weight. The results of FTIR analysis show that synthesizing polymethylsilsesquioxane (PMSQ) with methyltriethoxysilane (MTES) formed a regular structure such as the cage or ladder structure. The results of XRD and FTIR analysis show that the molecular structure started to change from regular to an irregular random network structure after grafting with tetraethoxysilane (TEOS) and 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTS) on the PMSQ. The changes in the molecular structure of SGPMSQ created by grafting silane are similar to the changes in the molecular structure of PMSQ film heated from 150 to over 250 °C, reducing the refractive index (RI). The RI of PMSQ at 583 nm decreased from 1.50 to 1.42 merely by heating it to 80 °C, introducing silane, and controlling the molecular structure. When the weight ratio of MTES:TEOS:PFDTS was 1:0.5:1, the decomposition temperature (Td) of SGPMSQ was 340 °C, which is much higher than that of pure PMSQ (Td = 267 °C). Although the glass transition temperature of SGPMSQ was 20 °C lower than that of pure PMSQ, its decomposition temperature was 73 °C higher. This shows that SGPMSQ is more flexible and has greater thermal stability than pure PMSQ.

In situ phosphatizing coating (ISPC) was invented and patented in 1994, where in situ phosphatizing reagent (ISPR) was shown to form a dense interfacial phosphate layer on and bond strongly with metal substrates, and simultaneously link with covalent bonds to the polymer top-layer. In this paper, we report the synthesis of ISPR-catalyzed polysilsesquioxane (PSSQ) oligomers by the sol-gel method. Using different amounts of ISPR, the well-defined nanonetwork structures of PSSQ were characterized by SEM. The dispersion of ISPR-catalyzed PSSQ in ISPC to form a stable and compatible organic-inorganic hybrid (ISPC/PSSQ) nanocoating was carried out. The nanocoating was applied on AlMg alloys (AZ31A, AZ31B and AZ91D), and the corrosion performance was characterized by salt spray test (ASTM B117) and electrochemical impedance spectroscopy (EIS). The cross-section of dry film nanocoating layer on AZ91D was characterized by TEM EDS elemental mapping analysis. It was shown that the ISPR-catalyzed PSSQ forms a dense and uniform interfacial passivation layer sited tightly on top of metal surface and beneath the polymer layer. A 400 nm thick interfacial passivation layer of PSSQ in the nanocoating on AZ91D was shown to pass 360 hours of salt spray test ( 0.5% corrosion area). The current and future development on self-healing of corrosion protection, Li as anodic protection for Mg in LiMg alloys and encapsulation and release of ISPC/PSSQ corrosion inhibitor in nanocontainer has been illustrated. The excellent corrosion protection performance of ISPC/PSSQ nanocoating on AlMg alloys will be discussed.

We herein describe the preparation and characterization of a phase-separated fluorinated polymethylsilsesquioxane (PMSQ), which may be used as an antireflective coating. The results of FTIR analysis showed that when PMSQ is synthesized from methyltrimethoxysilane (MTMS), it exists mostly in the form of a cage structure. Its reflectivity of normally incident light (R) may be reduced from 3.9 to 0.9% by grafting 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FTES) by means of a sot gel process. In the study described herein, the minimum reflectivity of PMSQ was lowered to less than 1% by coating it with a single layer of fluorinated polymethylsilsesquioxane, through phase segregation of PMSQ and FTES that took place during film formation. The RI of PMSQ at 550 nm was also reduced from 1.51 to 1.42 by heating at 80 degrees C for 30 min, a temperature suitable for substrates, such as plastics, that have low heat resistance. Wetting and adhesion to substrates were both improved by the additional grafting of tetraethoxysilane (TEOS), again by means of a sol gel process. Results of solid-state (29)Si NMR and GPC showed increases in T(3), Q(3), Q(4), and the molecular weight, which signal the effective grafting of both the TEOS and the FTES on the PMSQ, Results from energy-dispersive X-ray spectroscopy (EDX) show that the quantity of fluorine atoms at the surface of the PMSQ film increased from 0 to 22%, providing the evidence of the phase segregation within the PMSQ film. When FTES is used, we found an increase in the water contact angle from 92 degrees to 108 degrees, which indicated that the hydrophobicity at the PMSQ film surface increased by increasing the FTES content from 0 to 100 wt %, using the weight of MTMS as 100%.

In this study, a simple approach was developed to fabricate an extremely superamphiphobic coating material by the tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) sol–gel derived materials. TEOS and MTES derived moieties were designed for a physical roughness and hydrophobic surface characteristic, respectively. The 29Si solid-state NMR and ESCA analysis showed the coated silica composition was similar to the feeding ratios of TEOS/MTES. The surface structure characterized from SEM and TEM suggested the nanoparticle-based silica surface was observed at a high TEOS/MTES content but changed to a relatively smooth surface at a low TEOS content. The contact angles of water and CH2I2 on the pure TEOS derived coated surface were both 0° due to the hydrophilic Si–OH group. As the MTES composition increased to 25mol% (T5M3), the coated surface had the contact angles of 149.8° and 133.1° for water and CH2I2, respectively. It revealed that the T5M3-coated surface exhibited both super-hydrophobicity and super-oleophobicity, i.e., superamphiphobicity. Also, it had a relatively low-surface energy (1.38mJm−2) considerably lower than that of the F-silane-coated surface with 39.3mJm−2. As the MTES composition increased further, both contact angles of water and CH2I2 decreased. Especially, they decreased dramatically at the MTES feeding composition higher than 75mol%, due to the much less rough surface at a higher MTES composition. The present study suggests that superamphiphobic surface could be achieved by non-fluorinated sol–gel derived silica materials.

Superoleophobic surfaces possessing static contact angles greater than 140 degrees with organic liquids are extremely rare. A simple approach has been developed to fabricate an extremely superamphiphobic coating material based on fluorinated silica nanoparticles resulting contact angles of water and diiodomethane at 167.5 degrees and 158.6 degrees, respectively. The contact angle of diiodomethane at 158.6 degrees is substantially higher than the highest literature reported value we know of at 110 degrees. In addition, this developed film also possesses extremely high contact angles with other organic liquids such as soybean oil (146.6 degrees), decahysronaphthalene (142.5 degrees), diesel fuel (140.4 degrees), and xylene (140.5 degrees). This developed superamphiphobic organic-inorganic hybrid film possesses unique liquid repellency for both water and organic liquids that can be used as functional coatings on numerous substrates by a simple coating process. (C) 2008 Wiley Periodicals, Inc.