Chandan Bodhak

Covalent adaptable networks (CANs) are a pioneering member of the polymer family that have garnered significant attention in recent years and are characterized by covalent cross-links that exhibit reversible dynamic alterations in response to external stimuli. Additionally, unlike traditional thermosets, CANs, especially vitrimers, offer a range of properties such as self-healing, reprocessability, shape-reconfigurability, and recycling capabilities due to the dynamic nature of covalent cross-links. Recently, an increasing trend in the global production of thermosets involves the rapid consumption of petroleum-based resources, which has become a growing environmental concern. From this perspective, the development of eco-friendly thermosets from biobased feedstocks is a possible way to overcome these drawbacks. In this context, geraniol is one of the monoterpenoid alcohols, a primary component of several plant oils that has become a valuable replacement for petroleum-based resources. In this study, for the first time, a geraniol-derived epoxy vitrimer has been developed through a thermally triggered “thiol-epoxy click” reaction between the geraniol-based epoxy resin and a dynamic diboronic ester dithiol (DBDT) cross-linker. The resulting vitrimer exhibits excellent self-healing properties driven by topology alteration through the dynamic transesterification of boronic ester bonds. The fabricated Ger_epoxy-DBDT vitrimers possess excellent thermal stability and significant mechanical properties, with the absolute value of the glass transition temperature (Tg) of 38.43 °C determined from DMA analysis. Incorporating dynamic boronic ester linkages imparts an enhanced tensile strength of ∼19 MPa, enabling the vitrimer to recover its original shape after deformation (shape memory), solvent recycling ability, and excellent reprocessability with maximum restoration of mechanical strength. Moreover, the vitrimer was further characterized by a notably short relaxation time of around 9 s at 140 °C and an apparent activation energy of 22.44 kJ/mol. In a nutshell, the developed vitrimer demonstrates significant potential for use in various commercial sectors, and its reversible bond-breaking and bond-making ability under specific conditions offers opportunities for developing sustainable, high-performance materials.

Sustainability in additive manufacturing (AM) (3D printing) could play a pivotal role for manufacturers and producers in the next‐generation manufacturing framework. The market for 3D printing is expanding rapidly, and it is expected to do so in the foreseeable years to come. As ecologically, responsible manufacturing gains more attention, renewable substitutes for regular commercial 3D printable inks must be developed for lower environmental carbon footprints (less CO₂ emissions, recycling, bio‐compatibility, and zero waste). Herein, we review the recent literature on using vegetable oil (VO) as bio‐based inks for sustainable formulations for digital light processing or stereolithography additive printing. The feedstock selections (VO, terpenes, and waste cooking oil), and the chemistry of the VO‐based synthons toward sustainability in the field of photopolymerization‐based 3D printing are discussed. These renewable materials can mitigate the detrimental environmental effects of AM while remaining competitive with the existing fossil‐based resins produced by industrial manufacturers. The current challenges and limitations of AM in terms of surface finish, material properties, photo‐curing time, and end‐of‐use recycling options from biomass‐derived photocurable monomers are also identified. Overall, this development promotes the bio‐based economy and allows for the on‐demand production of a variety of sustainable inks for AM and sustainable end‐of‐use products.Highlights: The significance of vegetable oils (VOs) as photopolymerizable monomers is explored. The necessity for 3D printing, specifically recycling and end‐of‐use, for the industrial revolution is provided. Green developments in stereolithography/digital light processing 3D printing utilizing VOs are covered.

Over the past few decades, polymer composites have received significant interest and become protagonists due to their enhanced properties and wide range of applications. Herein, we examined the impact of filler and flame retardants in hemp seed oil-based rigid polyurethane foam (RPUF) composites’ performance. Firstly, the hemp seed oil (HSO) was converted to a corresponding epoxy analog, followed by a ring-opening reaction to synthesize hemp bio-polyols. The hemp polyol was then reacted with diisocyanate in the presence of commercial polyols and other foaming components to produce RPUF in a single step. In addition, different fillers like microcrystalline cellulose, alkaline lignin, titanium dioxide, and melamine (as a flame retardant) were used in different wt.% ratios to fabricate composite foam. The mechanical characteristics, thermal degradation behavior, cellular morphology, apparent density, flammability, and closed-cell contents of the generated composite foams were examined. An initial screening of different fillers revealed that microcrystalline cellulose significantly improves the mechanical strength up to 318 kPa. The effect of melamine as a flame retardant in composite foam was also examined, which shows the highest compression strength of 447 kPa. Significantly better anti-flaming qualities than those of neat foam based on HSO have been reflected using 22.15 wt.% of melamine, with the lowest burning time of 4.1 s and weight loss of 1.88 wt.%. All the composite foams showed about 90% closed-cell content. The present work illustrates the assembly of a filler-based polyurethane foam composite with anti-flaming properties from bio-based feedstocks with high-performance applications.