Synthesis and characterization of a vinyl-terminated benzoxazine monomer and its blends with poly(ethylene oxide)

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

Due to their outstanding and versatile properties, polybenzoxazines have quickly occupied a great niche of applications. Developing the ability to polymerize benzoxazine resin at lower temperatures than the current capability is essential in taking advantage of these exceptional properties and remains to be most challenging subject in the field. The current review is classified into several parts to achieve this goal. In this review, fundamentals on the synthesis and evolution of structure, which led to classification of PBz in different generations, are discussed. Classifications of PBzs are defined depending on building block as well as how structure is evolved and property obtained. Progress on the utility of biobased feedstocks from various bio-/waste-mass is also discussed and compared, wherever possible. The second part of review discusses the probable polymerization mechanism proposed for the ring-opening reactions. This is complementary to the third section, where the effect of catalysts/initiators has on triggering polymerization at low temperature is discussed extensively. The role of additional functionalities in influencing the temperature of polymerization is also discussed. There has been a shift in paradigm beyond the lowering of ring-opening polymerization (ROP) temperature and other areas of interest, such as adaptation of molecular functionality with simultaneous improvement of properties.

Development of sustainable and antimicrobial film based on polybenzoxazine and cellulose

A new class of bio based polymer blends have been prepared from a modified chitosan based benzoxazine precursor (E-ch) and amino cellulose (AC). AC was derived from cellulose with excellent film-forming, biocompatibility and biodegradability property. E-ch was synthesized from eugenol, modified chitosan and paraformaldehyde. The chemical structure was confirmed by FT-IR and ¹H NMR analyses. Bio films were prepared by mixing E-ch and AC with diluted acetic acid, in different ratios. These films were further cross-linked by applying heat, via ring-opening polymerization of benzoxazine without any curing agent. FT-IR and DSC were used to study the effects of AC on E-ch to form cross-linked network polymer films [poly(E-ch)/AC]. Hydrogen bonding interactions were found to exist between poly(E-ch) and AC. These kinds of interactions considerably improve the mechanical and thermal properties and char yield of the polymer films. Additionally, these biofilms; poly(E-ch) and poly(E-ch)/AC have been examined for bio-activity with S. aureus. It is confirmed that these bio-films are effective in inhibiting bio-film related infection. In a similar way, both the bio-films act against C. albicans and thus avoid the formation of mycological infection. These results expose that poly(E-ch) and AC bio-films are capable to act as anti-microbial and anti-fungal agents.

Flexible Epoxy Resins Formed by Blending with the Diblock Copolymer PEO-b-PCL and Using a Hydrogen-Bonding Benzoxazine as the Curing Agent

In this study, we enhanced the toughness of epoxy resin by blending it with the diblock copolymer poly(ethylene oxide⁻b⁻ε-caprolactone) (PEO-b-PCL) with a benzoxazine monomer (PA-OH) as the thermal curing agent. After thermal curing, Fourier transform infrared spectroscopy revealed that intermolecular hydrogen bonding existed between the OH units of the epoxy⁻benzoxazine copolymer and the C⁻O⁻C (C=O) units of the PEO (PCL) segment. Differential scanning calorimetry and dynamic mechanical analysis revealed that the glass transition temperature and storage modulus of the epoxy⁻benzoxazine matrix decreased significantly upon increasing the concentration of PEO-b-PCL. The Kwei equation predicted a positive value of q, consistent with intermolecular hydrogen bonding in this epoxy⁻benzoxazine/PEO-b-PCL blend system. Scanning electron microscopy revealed a wormlike structure with a high aspect ratio for PEO-b-PCL as the dispersed phase in the epoxy⁻benzoxazine matrix; this structure was responsible for the improved toughness.