Triazine networks

Usually an indication of molecular mixing can be theoretically calculated based on composite Tg s. When the glass transition temperature of the SIPN was between that of the neat components, molecular interactions were assumed. A definite increase in Tg resulted in these materials. No calculated Tg can be compared since the thermoset did not show a Tg. It was interesting to note that the beta transition of the triazine network was unaffected, but the Tg for the composite was much higher relative to the thermoplastic alone. System II showed a 20 C increase in Tg, while I showed a large increase, changing from 62 C to 125°C. 

It can be assumed that two separate networks with no covalent bonds between the UPR and the cyanate-based triazine network are formed. The possible addition of terminal hydroxyls from the unsaturated polyester to the —C = N bonds in BPA/DC is rather improbable as the addition of alcohols to cyanates, leading to iminocarbonate derivatives (Scheme 8), only occurs in the presence of strong alkali catalysts [134], The cyanate cyclotrimerization has been evidenced from disappearance of the 2230 and 2270 cm-1 and the appearance of 1370 and 1560 cm-1 absorption bands in the infrared spectra of the crosslinked IPN. 

Thermal properties of some other polymers containing heterocycles are reported in literature. For example, the polymers containing triazine networks substituted with perfluoro-rt-propyl or perfluoroalkyloxy groups do not decompose easily upon heating. These types of polymers are used as heat resistant oils, and several studies on their thermal decomposition are available in literature [21-23]. 

The molecular network structure suggested for CTF-1 is isoelectronic with the structure of COF-1 [14], By contrast, COF-1 shows a staggered, P6Jmmc hexagonal structure prior to CTF-1 is proposed to have eclipsed P6lmmm symmetry [15]. No NMR data was given for these triazine networks, but elemental analysis implied partial decomposition or carbonization in some samples. For example, a network produced... 

Modified phenolics may be applied as matrix resins in composites. Cyanate esters of phenolics have the potential to replace conventional phenolics in thermo-structural applications. Thermal curing of the cyanate esters [149, 150] provide thermally stable phenolic-triazine networks, as shown at the bottom of Scheme 18. 

Figure 10.4 Molecular dimensions of triazine network (adapted from Reference [37]).

Nair and co-workers [203] reported polycyanate esters of an imide-modified novolac of different maleimide content. The resins underwent a two-stage independent thermal curing through trimerisation of the cyanate groups, as well as addition polymerisation of maleimide moieties. On heating, cyanate esters were transformed into an imido-phenolic-triazine network polymer. The cured resins exhibited a higher initial decomposition temperature compared with the cured maleimide novolacs. However, the thermal stability was found to be inferior to the conventional phenolic-triazine resin. 

The synthesis of triazine-based networks follows nitrile self-condensation with ZnCl2 to give a series of highly porous networks. The 1,4-dicyano-benzene-based network was among the first triazine networks to show a high... 

Simple functionalities have also been used to perform catalytic transformations. Triazine networks have been used to perform cycloadditions to epoxides either using just the basic triazine units or via the incorporation of pyridines. ... 

Metal-functionalized CTFs have other important aspects. The Pt-loaded CTF shows high catalytic activity with recyclability towards methane oxidation at an elevated temperature in acidic media. A triazine network of 1,4-dicyanobenzene loaded with Pd nanoparticles has been shown to exhibit a better catalytic activity and lifetime than Pd-loaded activated carbon in the glycerol oxidation reaction. N-heterocyclic moieties of CTFs provide the required stability to Pd nanoparticles, while the rigid framework facilitates the selectivity of the catalyst. ... 

The predominant curing pathway for cyanate ester is via cyclotrimerization using metal coordination catalysts. Three types of metal coordination catalysts are used metal naphthenates, metal acetylacetonates (AcAc), and metal octoates. Of these, Cu AcAc and Mn octoate are the most popular. Nonylphenol is also required as a cocatalyst. Reaction 5 shows the cyclotrimerization reaction of bisphenol A dicyanate to form the triazine network structure ... 

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