Ring Opening Reaction of 3,4‐Dihydro‐2H‐1,3‐Benzoxazine with Amines at Room Temperature

Abstract

The ring-opening reaction of p-cresol-based 1,3-benzoxazine with amine at room temperature was investigated in different solvents. Results show that the reactions proceeded easily in protic solvents, but no reaction occurred in aprotic solvents. For different amines involved in the reactions, both primary and secondary amines can participate in the reaction with benzoxazine, while tertiary amines would hinder the progress of the nucleophilic reaction. The mechanism study demonstrated the feasibility of polymerization of the benzoxazine with amines at room temperature. Moreover, the crosslinking between bifunctional benzoxazine and diamine was realized at room temperature, and the polymer can be obtained.[a] J. Zong, Q. Ran

Review on the Accelerated and Low-Temperature Polymerization of Benzoxazine Resins: Addition Polymerizable Sustainable Polymers

“…The E a for polymerization reactions follows the basicity order of amine, arylamine > alicyclic amine > alkylamine. Primary, secondary and tertiary amines successfully assist ring opening reaction of mono-oxazine in polar solvents, and crosslinking reactions was realized in case of reaction of diamine with bis-benzoxazine at room temperature [324]. Addition of polypyrrole (PPy, 5 wt%) also mediates the ROP reaction, and T p value was significantly reduced for C-fa and BF-A, from 245 to 185 • C and 226 to 165 • C, respectively [325].…”

Improvement of aldehyde‐functional polybenzoxazine processability and mechanical properties achieved by 5‐aminoindole/benzoxazine copolymerization

“…These results suggest that the oxazine ring‐opening polymerization is markedly accelerated and low‐temperature curing is realized with incorporation of 5‐aminoindole. This represents great progress in the application of polybenzoxazines, considering a high curing temperature (>200 °C) is always needed for curing of benzoxazines 36,37 . The band assigned to aldehyde groups at 1679 cm −1 decreased significantly, while the indole absorption at 3403 cm −1 and the tertiary carbon absorption at 1345 cm −1 were detected after prepolymerization, indicating the branch rose indigo formed through the special reaction between the aldehyde groups and the indole groups.…”

“…This represents great progress in the application of polybenzoxazines, considering a high curing temperature (>200°C) is always needed for curing of benzoxazines. 36,37 The band assigned to aldehyde groups at 1679 cm −1 decreased significantly, while the indole absorption at 3403 cm −1 and the tertiary www.soci.org Y Xu et al…”

Hybrids from silazane and allyl‐containing benzoxazine for low‐curing temperature and high‐flame retardance

“…The curing reaction mechanism of these silicon‐containing benzoxazine is following the cationic ring‐opening mechanism, moreover, the addition reaction after ring opening still needs a curing temperature higher than 220°C 15–18 . To decrease the curing temperature of benzoxazine, many kinds of compounds, such as salt, 19,20 phenols, 21–23 acids, 24,25 and amines 26–28 were used to catalyze oxazine ring‐opening reaction.…”

“…In this study, we take advantage of the fact that the polysilazane have both amine groups and SiH bonds. The amine groups of the polysilazane can catalyze oxazine ring‐opening reaction 26–29 and SiH bonds can take place hydrosilylation reaction with an allyl group of benzoxazine. Therefore, we applied the reaction between the polysilazane and allyl‐functional benzoxazine monomers to get a new silicon hybrid benzoxazine with low‐curing temperature.…”