@article {49293, title = {Biobased reusable nonisocyanate polyurethane hot-melt adhesives with potential chemical degradability}, journal = {ACS Applied Polymer Materials}, volume = {6}, year = {2024}, month = {SEP}, pages = {11180-11192}, type = {Article}, abstract = {

Hot-melt adhesives (HMAs) derived from renewable resources are always attractive, as they promote less dependence on fossil resources and aid in developing environmentally friendly materials. However, developing sustainable HMAs exhibiting good adhesive performance and biodegradability remains challenging. Herein, reusable biobased HMAs with a high bio content of 88-90\%, biodegradability, and tunable adhesive nature were developed as a possible alternative to conventional petroleum-based hot-melt adhesives. Moreover, the structure-property relationship of the product was investigated in detail. By tailoring the monomer composition, NIPU-40 HMA exhibited a good bonding ability with a superior adhesion strength of 6.39 MPa. To the best of our knowledge, this is the highest adhesion strength observed when bonding with an Al substrate among the biobased thermoplastic NIPU-HMAs. Impressively, NIPU-HMAs could display excellent reusability even after three bonding and debonding cycles without a significant drop in the adhesive strength and were found to exhibit good adhesion performance under wet conditions. More importantly, the NIPU-HMAs are prone to degradation under acid-catalyzed conditions. Considering their features, these biobased NIPU thermoplastic hot-melt adhesives offer an opportunity to create environmentally friendly, degradable adhesives that possess excellent adhesive strength and can be reused multiple times.

}, keywords = {acid degradability, biobased NIPUs, cyclic carbonates, hot meltadhesives, lap shearstrength, spiro-aromatic}, issn = {2637-6105}, doi = {10.1021/acsapm.4c01526}, author = {Ghuge, Gorakh Hiraman and Torris, Arun and Nair, Kiran Sukumaran} } @article {49087, title = {Biodegradable and 3D printable lysine functionalized polycaprolactone scaffolds for tissue engineering applications}, journal = {Biomaterials Advances}, volume = {159}, year = {2024}, month = {MAY}, pages = {213816}, type = {Article}, abstract = {

Tissue engineering (TE) has sparked interest in creating scaffolds with customizable properties and functional bioactive sites. However, due to limitations in medical practices and manufacturing technologies, it is challenging to replicate complex porous frameworks with appropriate architectures and bioactivity in vitro. To address these challenges, herein, we present a green approach that involves the amino acid (L-lysine) initiated polymerization of epsilon-caprolactone (CL) to produce modified polycaprolactone (PCL) with favorable active sites for TE applications. Further, to better understand the effect of morphology and porosity on cell attachment and proliferation, scaffolds of different geometries with uniform and interconnected pores are designed and fabricated, and their properties are evaluated in comparison with commercial PCL. The scaffold morphology and complex internal micro-architecture are imaged by micro-computed tomography (micro-CT), revealing pore size in the range of similar to 300-900 mu m and porosity ranging from 30 to 70 \%, while based on the geometry of scaffolds the compressive strength varied from 143 +/- 19 to 214 +/- 10 MPa. Additionally, the degradation profiles of fabricated scaffolds are found to be influenced by both the chemical nature and product design, where Lys-PCL-based scaffolds with better porosity and lower crystallinity degraded faster than commercial PCL scaffolds. According to in vitro studies, Lys-PCL scaffolds have produced an environment that is better for cell adhesion and proliferation. Moreover, the scaffold design affects the way cells interact; Lys-PCL with zigzag geometry has demonstrated superior in vitro vitality (\>90 \%) and proliferation in comparison to other designs. This study emphasizes the importance of enhancing bioactivity while meeting morphology and porosity requirements in the design of scaffolds for tissue engineering applications.

}, keywords = {Additive manufacturing, Amino acid, Micro-computed tomography, Polycaprolactone}, doi = {10.1016/j.bioadv.2024.213816}, author = {Naik, Sonali S. and Torris, Arun and Choudhury, Namita R. and Dutta, Naba K. and Nair, Kiran Sukumaran} } @article {49783, title = {Bio-based poly(isobornyl acrylate)-b-(citronellyl methacrylate) block copolymers by PET-RAFT polymerization: thiol-ene modification and adhesion studies}, journal = {Journal of Macromolecular Science Part A-Pure and Applied Chemistry}, volume = {62}, year = {2025}, month = {SEP }, pages = {728-736}, type = {Article}, abstract = {

In this study, poly(isobornyl acrylate)-b-poly(citronellyl methacrylate) (PIBA-b-PCMA) block copolymers were synthesized with controlled molecular weights and low dispersity using photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization of isobornyl acrylate (IBA) and citronellyl methacrylate (CMA), both terpene-derived monomers. A series of block copolymers was obtained by varying the chain length of PCMA block. Kinetics study of the polymerization of IBA and CMA using 4-cyano-(((dodecylthio)carbonothioyl)thio)pentanoic acid (CDTPA) as chain transfer agent showed a linear plot of ln[M]0/[M]t vs time indicating first order reaction. Distinct glass transition temperatures were observed for the individual blocks and enhanced thermal stability was seen with increasing PCMA content. Post-polymerization modification of the polymer was demonstrated using thiol-ene reaction with the vinyl group in the pendent citronellyl moiety. Adhesion performance, evaluated through lap shear test on aluminum substrates, showed that the block copolymers achieved peak shear strengths of 1.74 MPa at a 38:62 PIBA:PCMA mole ratio.

}, keywords = {adhesion strength, Bio-based polymers, block copolymers, PET-RAFT polymerization, Thiol-ene reaction}, issn = {1060-1325}, doi = {10.1080/10601325.2025.2546128}, author = {Hetkale, Pragati M. and Purohit, Poorvi M. and Nair, Kiran Sukumaran and Ambade, Ashootosh V.} }