Oxidative Deconstruction of Olefin functionalized Polyethylene terephthalate

Polyethylene terephthalate (PET) is a widely used thermoplastic with a global production of ~50 MMT in 2016 and is expected to grow at a CAGR of 9.7% by 2022. This exceptional market presence can be attributed to desired chemical, mechanical, optical, and thermal properties suited to its ideal candidature in the food and beverage packaging industries. PET consumerism is plagued with environmental persistence with no measurable degradation observed in landfills (half-life of >2500 days). The recent governmental ban imposed by several countries on single-use plastics faced an immediate reversal to limiting the rampant spread of COVID-19, sowing the seeds for a plastic pandemic, making a solid case for true recycling. Chemical disassembly of polymers to re-polymerizable units by modifying existing plastics at source offers a robust strategy against a twofold crisis of both limited petrochemical resources and post-consumer waste. This study entails modification of traditional PET with chemically reactive moieties such as an olefinic diacid viz. hexadec-8-enedioic acid that upon application of a selective chemical trigger i.e. a strong oxidant unzips the polymer to its monomeric predecessors. This entails the forming glycol adducts of the long-chain olefinic moiety inserted into the conventional PET chain, which can provide centers for oxidative cleavage in the presence of a strong oxidant that initiates the depolymerization mechanism. Oxidative breakdown accompanied by subsequent hydrolysis resulted in monomers and oligomers at chemically mild conditions realizing recycling at the molecular level which upon re-polymerization should result in at par performance properties with virgin PET

Plastic Glut down a Microbial Gut

Enzymes sequestered from microbes have demonstrated the ability to readily digest amorphous regions of polyethylene terephthalate (PET) at ambient conditions. Though nascent, enzymatic depolymerization can soon vie for commercialization and provide monomeric feedstock at rates comparable to petrochemical feedstock for repolymerization and achieve the coveted goal of cradle-to-cradle recycling.This is the peer-reviewed version of the following article: Dileep, Dhananjay, Michael Forrester, and Eric Cochran. "Plastic Glut down a Microbial Gut." Polymer International (2022), which has been published in final form at DOI: 10.1002/pi.6369. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Copyright 2022 Wiley. Posted with permission

Challenging the existent dogma - synthetic mesh placement in enterostomy closure

Background & Aims: Enterostomy reversal and fascial defect cause weakness in the abdominal wall and may lead to formation of incisional hernia. Literature says that placement of synthetic mesh in dirty/contaminated wound causes high chances of surgical site infection (SSI) and mesh related complications. This dogma is now challenged. Present study was conducted to evaluate outcome of the placement of synthetic non-absorbable mesh after enterostomy closure in terms of SSI and incisional hernia. Materials & Methods: This prospective case-control study was conducted in the department of General surgery Netaji Subhash Chandra Bose (NSCB) medical college, Jabalpur, between 1st December 2018 to 30th September 2020. All patients of age >18 years with ileostomy/colostomy undergoing enterostomy reversal were included. Outcomes noted for wound infection/dehiscence, mesh related complications, its removal, and development of incisional hernia. Results: Total 60 patients were included in this study. Out of which, 30 (23 loop ileostomy, 5 double barrel ileostomy, and 2 colostomy) were taken as the case; where polypropylene mesh was placed (9 sublay and 21 onlay). 30 others (28 loop ileostomy, 1 double barrel ileostomy, and 1 colostomy) were taken as control where mesh was not placed after stoma closure. SSI was significantly lower in mesh placed group than non-mesh placed group (16.6% vs. 40%; P=0.019). Use of mesh was associated with slightly better outcomes but not significant in terms of rate of wound dehiscence (3.3% vs. 6.7%; Z=0.59; P=0.554) and incisional hernia (0 vs 6.7%; p= 0.492) in mesh and non-mesh groups, respectively. Mesh removal for chronic infection was not required in any case. Conclusion: Placement of permanent synthetic polypropylene mesh at the site of enter ostomy closure for prevention of incisional hernia can be done safely without fear of having increased risk of SSI and need of mesh removal

Single-use, Metabolite Absorbing, Resonant Transducer (SMART) culture vessels for label-free, continuous cell culture progression monitoring

Secreted metabolites are an important class of bio-process analytical technology (PAT) targets that can correlate to cell condition. However, current strategies for measuring metabolites are limited to discrete measurements, resulting in limited understanding and ability for feedback control strategies. Herein, we demonstrated a continuous metabolite monitoring strategy using a single-use metabolite absorbing resonant transducer (SMART) to correlate with cell growth. Polyacrylate was shown to absorb secreted metabolites from living cells containing hydroxyl and alkenyl groups such as terpenoids, that act as a plasticizer. Upon softening, the polyacrylate irreversibly conformed into engineered voids above a resonant sensor, changing the local permittivity which is interrogated, contact-free, with a vector network analyzer. Compared to sensing using the intrinsic permittivity of cells, the SMART approach yields a 20-fold improvement in sensitivity. Tracking growth of many cell types such as Chinese hamster ovary, HEK293, K562, HeLa, and E. coli cells as well as perturbations in cell proliferation during drug screening assays were demonstrated. The sensor was benchmarked to show continuous measurement over six days, ability to track different growth conditions, selectivity to transducing active cell growth metabolites against other components found in the media, and feasibility to scale out for high throughput campaigns.This is a preprint from Reuel, Nigel Forest, Yee Jher Chan, Dhananjay Dileep, Samuel Rothstein, and Eric Cochran. "Single-use, Metabolite Absorbing, Resonant Transducer (SMART) culture vessels for label-free, continuous cell culture progression monitoring." bioRxiv (2024): 2024-01. doi: https://doi.org/10.1101/2024.01.27.577601. Copyright 2024 The Authors

Toward Intrinsically Flame-Retardant, Bioenabled Nitrogen Aromatic Nylon 6,6 Comonomers

Muconic acid and its hydrogenation product trans-3-hexenedioic acid (t3HDA) are promising diacid monomers for inserting property enhancements as functionalities into nylon 6,6. A present challenge is related to low reaction yields and the high sophistication of syntheses. A green, atom-economical functionalization reaction that minimizes processing steps is desired. In this work base catalyzed isomerization was used to produce trans-2-hexenedioic acid (t2HDA) under mild conditions, and graft nitrogen based aromatic thiols to t2HDA via Michael addition in gamma-Valerolactone (GVL). The grafted monomers were co-polymerized with adipic acid and hexamethylenediamine (HMDA), and the flame-retardant properties of the synthesized polyamides screened to identify promising nitrogen-containing aromatics to afford improvements in end use performance without compromising on the polyamide’s properties.This is a manuscript of an article published as Hadel, Joseph, Sohaima Noreen, Marco Nazareno Dell’anna, Dhananjay Dileep, Brent H. Shanks, Jean-Philippe Tessonnier, and Eric W. Cochran. "Toward Intrinsically Flame-Retardant, Bioenabled Nitrogen Aromatic Nylon 6, 6 Comonomers." In Sustainable Green Chemistry in Polymer Research. Volume 2. Sustainable Polymers and Applications, pp. 163-176. American Chemical Society, 2023. doi:10.1021/bk-2023-1451.ch008. Posted with Permission. Copyright © 2023American Chemical Societ

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Dihydroxyterephthalate—A Trojan Horse PET Counit for Facile Chemical Recycling

Here, low-energy poly(ethylene terephthalate) (PET) chemical recycling in water: PET copolymers with diethyl 2,5-dihydroxyterephthalate (DHTE) undergo selective hydrolysis at DHTE sites, autocatalyzed by neighboring group participation, is demonstrated. Liberated oligomeric subchains further hydrolyze until only small molecules remain. Poly(ethylene terephthalate-stat-2,5-dihydroxyterephthalate) copolymers were synthesized via melt polycondensation and then hydrolyzed in 150–200 °C water with 0–1 wt% ZnCl2, or alternatively in simulated sea water. Degradation progress follows pseudo-first order kinetics. With increasing DHTE loading, the rate constant increases monotonically while the thermal activation barrier decreases. The depolymerization products are ethylene glycol, terephthalic acid, 2,5-dihydroxyterephthalic acid, and bis(2-hydroxyethyl) terephthalate dimer, which could be used to regenerate virgin polymer. Composition-optimized copolymers show a decrease of nearly 50% in the Arrhenius activation energy, suggesting a 6-order reduction in depolymerization time under ambient conditions compared to that of PET homopolymer. This study provides new insight to the design of polymers for end-of-life while maintaining key properties like service temperature and mechanical properties. Moreover, this chemical recycling procedure is more environmentally friendly compared to traditional approaches since water is the only needed material, which is green, sustainable, and cheap.This is the published version of the following article: Lee, Ting‐Han, Michael Forrester, Tung‐ping Wang, Liyang Shen, Hengzhou Liu, Dhananjay Dileep, Baker Kuehl, Wenzhen Li, George Kraus, and Eric Cochran. "Dihydroxyterephthalate—A Trojan Horse PET Counit for Facile Chemical Recycling." Advanced Materials 35, no. 21 (2023): 2210154. DOI: 10.1002/adma.202210154. Copyright 2023 The Authors. Attribution 4.0 International (CC BY 4.0). Posted with permission

Multifunctional Biobased Comonomers for Flame-Retardant Polyamides with Superior Mechanical Properties

Efforts towards developing biobased chemicals primarily focus on generating molecules chemically analogous to those derived from petroleum. However, the compositional uniqueness of biomass can also be leveraged to reinvigorate the chemical industry with novel multifunctional molecules. We demonstrate the value and potential of these new compounds in the case of Nylon-6,6, a commodity polyamide that suffers from poor flame resistance. The conventional route to inhibit flammability involves blending the polymer with additives, an approach that comes with significant trade-offs on the mechanical properties of the final product compared to the parent polyamide. Herein, we address this limitation through synthesis of a novel multifunctional comonomer derived from renewably sourced trans-3-hexenedioic acid (t3HDA). t3HDA was subjected to a one-pot isomerization and functionalization strategy where the double bond migrates to render this molecule active for phospha-Michael-addition (MA) with 6-oxide6H-dibenz(1,2)oxaphosphorin (DOPO), a prominent halogen-free flame-retardant (FR). This monomer was introduced in the polyamide’s backbone through copolymerization and the obtained polymer was compared to physical mixtures containing proportionate amounts of DOPO and Nylon-6,6. Thermal and mechanical properties of the blends and the FR-grafted polymers were characterized through a suite of techniques that revealed superior crystallinity, thermal, and mechanical properties for the DOPO-tethered bio-advantaged polyamides relative to blends with comparable flame retardance. The synthesis strategy presented herein can be extended for a variety of functional groups for property-modified bio-advantaged polymers.This is a preprint from Carter, Prerana, Ting-Han Lee, Peter M. Meyer, Dhananjay Dileep, Nickolas L. Chalgren, Sohaima Sohaima, Michael J. Forrester, Brent H. Shanks, Jean-Philippe Tessonnier, and Eric W. Cochran. "Multifunctional Biobased Comonomers for Flame-Retardant Polyamides with Superior Mechanical Properties." (2023). doi: https://doi.org/10.26434/chemrxiv-2023-nnww9. Copyright Authors 2023. The content is available under CC BY NC ND 4.0

Multifunctional Biobased Comonomers for Flame-Retardant Polyamides with Superior Mechanical Properties

Efforts towards developing biobased chemicals primarily focus on generating molecules chemically analogous to those derived from petroleum. However, the compositional uniqueness of biomass can also be leveraged to reinvigorate the chemical industry with novel multifunctional molecules. We demonstrate the value and potential of these new compounds in the case of Nylon-6,6, a commodity polyamide that suffers from poor flame resistance. The conventional route to inhibit flammability involves blending the polymer with additives, an approach that comes with significant trade-offs on the mechanical properties of the final product compared to the parent polyamide. Herein, we address this limitation through synthesis of a novel multifunctional comonomer derived from renewably sourced trans-3-hexenedioic acid (t3HDA). t3HDA was subjected to a one-pot isomerization and functionalization strategy where the double bond migrates to render this molecule active for phospha-Michael-addition (MA) with 6-oxide6H-dibenz(1,2)oxaphosphorin (DOPO), a prominent halogen-free flame-retardant (FR). This monomer was introduced in the polyamide’s backbone through copolymerization and the obtained polymer was compared to physical mixtures containing proportionate amounts of DOPO and Nylon-6,6. Thermal and mechanical properties of the blends and the FR-grafted polymers were characterized through a suite of techniques that revealed superior crystallinity, thermal, and mechanical properties for the DOPO-tethered bio-advantaged polyamides relative to blends with comparable flame retardance. The synthesis strategy presented herein can be extended for a variety of functional groups for property-modified bio-advantaged polymers

Elevated highly sensitive C-reactive protein and d-dimer levels are associated with food insecurity among people living with HIV in Pune, India.

OBJECTIVE: To assess the prevalence and determinants of food insecurity among people living with HIV (PLWH) in Pune, India and its association with biomarkers known to confer increased risks of morbidity and mortality in this population. DESIGN: Cross-sectional analysis assessing food insecurity using the standardized Household Food Insecurity Access Scale. Participants were dichotomized into two groups: food insecure and food secure. Logistic regression models were used to assess associations between socio-economic, demographic, clinical, biochemical factors and food insecurity. SETTING: Antiretroviral therapy (ART) centre of Byramjee Jeejeebhoy Government Medical College and Sassoon General Hospitals (BJGMC-SGH), Pune, a large publicly funded tertiary and teaching hospital in western India.ParticpantsAdult (≥18 years) PLWH attending the ART centre between September 2015 and May 2016 who had received ART for either ≤7d (ART-naïve) or ≥1 year (ART-experienced). RESULTS: Food insecurity was reported by 40 % of 483 participants. Independent risk factors (adjusted OR; 95 % CI) included monthly family incom