Polymer and Soft Material Research (PSMR) GroupResearch Work
Three-dimensional printing (3DP), or additive manufacturing is a revolutionary or disruptive technology which is impacting wide areas of applications ranging from automotive industry to biomedical materials. The material requirement catering to the different AM technologies like material extrusion, material jetting, Vat photopolymerization, etc are in different forms – solid powder, liquid, paste or fiber. The wide scope for material development is both challenging and exciting. Glimpses of our foray into this exciting research area are given below. Our group also has been working in the area of development of p-Conjugated Polymers for potential application in energy harvesting and storage devices for the past decade. One of the biggest challenges impacting the commercialization of the p conjugated polymers is the difficulties in their scale up by the traditional method of batch-to-batch synthesis, which is prone to discrepancies in their molecular weights and molecular weight dispersities. Such variation in the molecular weight has been shown to result in fluctuations in their device performance. Continuous Flow Synthesis is an alternative technology to the traditional batch wise synthesis, which offers reaction conditions that are always exactly the same, regardless of the scale. Details of the research activities currently being pursued in the group in the area of continuous flow synthesis of pi conjugated polymers are given below.
Material Development for Light Based 3D Printing Applications
Light based additive manufacturing involving photopolymerization is a simple and convenient method for achieving high resolution 3D printed objects. In recent years there is an increasing demand for biodegradable materials that are amenable for bio 3D printing. The research activities in our group in this regard focuses on developing photopolymerizable monomers and crosslinkers based on biodegradable materials like polylactide (PLA), and amino acids. Suitably functionalized Poly(amino acids) are synthesized incorporating fluorescent moieties that not only aid in modulating the viscosity of the resin formulation but could also function as a light blocker, thereby improving the resolution of the 3D printed objects.
Continuous Flow Synthesis of p-Conjugated Polymers P(NDI2OD-T2) also known as Polyera ActivInk N2200 is a widely used nonfullerene acceptor polymer, which is a promising material for optoelectronic applications such as organic photovoltaics (OPVs), organic light-emitting diodes (OLEDs), organic field-effect transistor (OFETs), supercapacitor electrode material, spintronics application etc. A new A-B-A monomer was designed by flanking naphthalene diimide with bithiophene units in the bay position, which was further polymerized with bay substituted 1, 4-dibromo naphthalene diimide to afford the same polymer structure as P(NDI2OD-T2). The new monomer design resulted in very high molecular weight (Mn: 99.5 kDa, ÐM: 2.8) defect-free polymer in quantitative yield by the atom-economic Direct Hetero Arylation Polymerization (DHAP) route. The adoption of continuous flow technique to DHAP has the challenge of pumping a high-solid-content heterogenous reaction mixture through narrow reactors. Our research group presents the first report of the synthesis of P(NDI2OD-T2) by Continuous Flow Process adopting DHAP route to obtain a defect-free polymer with reasonable molecular weights.
Schematic representation of different monomer designs adopted to synthesize P(NDI2OD-T2)
Enantioselective Separation Using Chiral Amino Acid Functionalized pi Conjugated Polymers The differences in the activities of enantiomers of chiral molecules have developed a quest among the scientific community and industries to develop robust, scalable, and efficient strategies to produce enantiopure chemical compounds. Our research group has designed and developed polymers like polyfluorene with a chiral pendant like protected D/L-Aspartic acid, protected L-glutamic acid, protected L-tryptophan, and cost-effective commodity polymer like chiral polystyrene by post polymer modifications and applied simple filtration based enantioselective separation methodology for enantioselective separation. The enantioselective separation efficiency (ee %) could be enhanced by coating the chiral polymers on commercially available porous Anodic aluminium oxide membranes (AAO) or by preparing polymeric microspheres in case of chiral polystyrene. We also made use of the DHAP approach for the synthesis of chiral π-conjugated copolymers of fluorene and thiophene with helical sense, and undertook structure-property relationship analysis to understand the effect of steric hindrance and pendant length, on the conformational characteristics of the polymers.
§ Shrikant B. Nikam, Asha SK*. Enantioselective Separation of Amino Acids Using Chiral Polystyrene Microspheres Synthesized by Post Polymer Modification Approach. ACS Polymers Au (invited article) 2022, 2, 257−265. https://doi.org/10.1021/acspolymersau.2c00004. § Shrikant B. Nikam, Asha SK*. Enantioselective Separation Using Chiral Amino Acid Functionalized Polyfluorene Coated on Mesoporous Anodic Aluminum Oxide Membranes. Analytical Chemistry 2020, 92, 6850−6857.
CENTRE FOR EXCELLENCE IN THE FIELD OF PETROCHEMICALS: Specialty polymers for Customized Additive Manufacturing
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