A novel aromatic diamine-based benzoxazine (P-mPDA) is successfully synthesized from m-phenylenediamine (m-PDA), 2-hydroxybenzaldehyde, and formaldehyde. The polymerization behavior of P-mPDA and the properties of its thermoset are studied. The results indicate that P-mPDA owns favorable processability including low polymerization temperature, low liquefying temperature, and wide processing window. Even lower polymerization temperature (polymerization onset temperature as low as 80 °C) can be achieved by the promotion of catalysts. The ring-opening polymerization of P-mPDA first generates polybenzoxazine with N, O-acetal-type structure and arylamine Mannich-type structure, following which rearrangement from N, O-acetal-type structure to phenolic Mannich-type structure proceeds at elevated temperature. Furthermore, the polymerized P-mPDA shows outstanding performance such as extremely high glass transition temperature (T_g) of 280 °C, high char yield above 53% at 800 °C under nitrogen and excellent mechanical property. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43368.

A trifunctional epoxy containing oxyphenylene unit, triglycidyl of 4-(4-aminophenoxy)phenol (TGAPP) was synthesized and characterized. The chemical structure of TGAPP was confirmed with FTIR and ¹H-NMR. DSC analysis revealed that the reactivity of TGAPP with curing agent 4, 4′-diaminodiphenylsulfone (DDS) was significantly lower than that of triglycidyl para-aminophenol (TGPAP). Rheological analysis showed that the processing window of TGAPP/DDS was 20°C wider compared with that of TGPAP/DDS. The thermal and mechanical properties of cured TGAPP/DDS were investigated and compared with those of the cured TGPAP/DDS. Experimental results showed that, due to the introduction of oxyphenylene unit, the heat resistance and flexural strength were slightly reduced, while the tensile strength and impact strength were enhanced. SEM also confirmed that the introduction of oxyphenylene unit could enhance the toughness of the TGAPP/DDS as evident from ridge formation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41878.

A novel aromatic diamine-based benzoxazine monomer (PDETDA) was successfully prepared from diethyltoluenediamine (DETDA), phenol, and paraformaldehyde through a simple one-step solvent-less method. The structure of PDETDA was confirmed by FTIR, ¹H NMR, and ¹³C NMR. The curing behavior of PDETDA was studied by DSC, FTIR, and rheological measurement. The results showed that the alkyl substituents on the benzene ring in DETDA not only facilitated the synthesis of PDETDA by effectively hindering the formation of triazine network, but also endowed PDETDA with the advantage of low viscosity (1 Pa s at 90°C). However, steric hindrance of the substituents made PDETDA difficult to form a crosslinked network through ring-opening polymerization, and therefore only oligomers and noncrosslinked polymers were obtained. The curing kinetics of PDETDA was studied by nonisothermal DSC, and the results revealed that the curing of PDETDA displayed autocatalytic characteristic. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41920.

Tetra-functional epoxy resin N,N,N′,N′-tetraglycidyl-3,3′-diethyl-4,4′-diaminodiphenylmethane (TGDEDDM) was synthesized and characterized. The viscosity of TGDEDDM at 25°C was 7.2 Pa·s, much lower than that of N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM). DSC analysis revealed that the reactivity of TGDEDDM with curing agent 4,4′-diamino diphenylsulfone (DDS) was significantly lower than that of TGDDM. Owing to its lower viscosity and reactivity, TGDEDDM/DDS exhibited a much wider processing temperature window compared to TGDDM/DDS. Trifluoroborane ethylamine complex (BF₃-MEA) was used to promote the curing of TGDEDDM/DDS to achieve a full cure, and the thermal and mechanical properties of the cured TGDEDDM were investigated and compared with those of the cured TGDDM. It transpired that, due to the introduction of ethyl groups, the heat resistance and flexural strength were reduced, while the modulus was enhanced. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 40009.

Two new epoxy resins, diglycidyl ether of ethoxylated bisphenol-A (BPA) with two and six oxyethylene units (DGEBAEO-2 and DGEBAEO-6) were synthesized and characterized. DGEBAEO-6 was used to toughen the conventional epoxy resin diglycidyl ether of BPA (DGEBA). The blends of DGEBA with different amounts of DGEBAEO-6 were cured by 4,4′-diamino diphenylmethane (DDM), and their thermal and mechanical properties were examined. The DSC and DMA results presented that DGEBA/DGEBAEO-6 blends exhibited a homogenous phase, and the glass transition temperature of the blends was inversely proportional to the content of DGEBAEO-6. The impact strength of the cured blends was directly proportional to the content of DGEBAEO-6, and reached five times higher than that of the neat DGEBA when 50 wt % DGEBAEO-6 was used; the same impact strength was achieved for DDM-cured DGEBAEO-2. The viscosities of the blends decreased with increasing the DGEBAEO-6 content, whereas the tensile and flexural strength and the thermal stabilities were not obviously affected. Scanning electron microscopic results confirmed that the plastic deformation inducing by the incorporated flexible oxyethylene units was responsible for the toughness improvement. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Optically clear silicone/epoxy hybrid resins were synthesized. The silicone resin (SiR) carrying SiH, SiCHCH₂ and SiOH groups was prepared by hydrolytic condensation. The blends of SiR and diglycidyl ether of hydrogenated bisphenol A (DGEHBA) were cured through platinum-catalyzed hydrosilylation and aluminium acetylacetonate-catalyzed polymerization. The curing process was studied using differential scanning calorimetry and rigid-body pendulum rheometry. It was found that the ratio of SiR to DGEHBA plays a major role in the curing process. The SiOH groups of SiR assist polymerization of DGEHBA, and react with the epoxy resin to prevent phase separation. The cured hybrid resins are single-phase materials with a transmittance of about 87% at 400 nm for a thickness of 3 mm using air as reference. UV resistance and thermal stability of the hybrids are largely dependent on the composition. The adhesive strength of the SiRs can be significantly improved by a small fraction of DGEHBA, with a marginal influence on UV resistance. However, increasing the epoxy proportion has a marked negative influence on thermal stability. Compounding stabilizers, especially thermal stabilizers, are essential, in particular for high epoxy content, if the hybrids are to be used for high-brightness light-emitting diode packaging. Copyright © 2011 Society of Chemical Industry

Silicone–epoxy (SiE) resins were synthesized through the hydrolytic condensation of 2-(3,4-epoxycyclohexylethyl) methyldiethoxysilane (EMDS) and the cohydrolytic condensation of EMDS with dimethyldiethoxysilane. Structural characterization was carried out by ¹H-NMR, ²⁹Si-NMR, and mass spectrometry analysis; the resins were linear oligomers bearing different numbers of pendant epoxy groups, and the average number of repeat SiO units ranged from 6 to 11. Methyhexahydrophthalic anhydride was used to cure the SiE resins to give glassy materials with high optical clarity. The cured SiE resins showed better thermal stability and higher thermal and UV resistances than a commercial light-emitting diode package material (an epoxy resin named CEL-2021P). The effect of the epoxy value on the thermal and mechanical properties and the thermal and UV aging performances of the cured SiE resins were investigated. The SiE resins became more flexible with decreasing epoxy value, and the resin with the moderate epoxy value had the highest thermal and UV resistances. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011