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1. Effect of exchange reactions and free radical grafting on the high‐speed reactive extrusion of poly(butylene succinate) and poly(propylene carbonate) blends

   https://doi.org/10.1002/pen.25197  

   Calderón, Bárbara A. ; Thompson, Conor W. ; Barinelli, Vincenzo L. ; McCaughey, Matthew S. ; Sobkowicz, Margaret J. ( August 2019 , Polymer Engineering & Science)

   The potential of exchange reactions using titanium butoxide (TBT) as catalyst for the compatibilization of poly(butylene succinate) and poly(propylene carbonate) was explored, and the effects of high speed reactive extrusion on the ester–carbonate exchange reaction were studied. The feasibility of this functionalization route was contrasted to the free radical grafting (FRG) type using maleic anhydride and a peroxide. First, batch mixing and solution blending were conducted to determine the suitable amount of catalyst for blends of this kind. Then, blends at different screw speeds, reaching 1,000 rpm were compounded with catalyst on a twin‐screw extruder. Spectroscopy techniques corroborated the formation of block and graft copolymers on the TBT and FRG samples, respectively. Both compatibilization paths produce a positive change in the mechanical properties of the system that was accompanied by a finer droplet size and better interfacial interaction. Specifically, the high‐speed runs using a catalyst demonstrated a 177% improvement of the strain at break, proving that the high mechanical energy imparted impacts positively the mixing performance. POLYM. ENG. SCI., 59:1986–1998, 2019. © 2019 Society of Plastics Engineers

    

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2. Hemicubane topological analogs of the oxygen-evolving complex of photosystem II mediating water-assisted propylene carbonate oxidation

   https://doi.org/10.1039/D1CC05825H  

   Koellner, Connor A. ; Gau, Michael R. ; Polyak, Aleksander ; Bayana, Manish ; Zdilla, Michael J. ( February 2022 , Chemical Communications)

   A series of Ca–Mn clusters with the ligand 2-pyridinemethoxide (Py-CH 2 O) have been prepared with varying degrees of topological similarity to the biological oxygen-evolving complex. These clusters activate water as a substrate in the oxidative degradation of propylene carbonate, with activity correlated with topological similarity to the OEC, lowering the onset potential of the oxidation by as much as 700 mV. 

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3. Kinetic Model of Maleic Anhydride Grafting onto Poly(Propylene Carbonate) during Melt Compounding

   https://doi.org/10.1002/mats.201900038  

   Calderón, Bárbara A. ; Bauer, Michel E. ; Thompson, Conor W. ; Sobkowicz, Margaret J. ( September 2019 , Macromolecular Theory and Simulations)

   The functionalization of poly(propylene carbonate) (PPC) by means of both free radical and esterification grafting of Maleic anhydride (MAH) aided by a peroxide is simulated by means of a kinetic model. The amount of MAH grafted (A_g) measured from batch mixer trials shows good agreement with the simulated results. Sensitivity analysis of the different rate constants shows that peroxide decomposition is the factor that drives the reaction, meaning that the choice of initiator affects greatly the reaction conversion. The next most dominant reaction is the chain ends esterification. There is a competing effect between chain initiation and side reactions, however, chain initiation is slightly more dominant than the latter. It is also found that higher content of peroxide induces higherA_g. The amount of MAH has a lower impact onA_gat low peroxide concentration; however, it becomes more influential in the presence of more peroxide.

    

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4. Catalytic Conversion of Biomass-Derived 1,2-Propanediol to Propylene Oxide over Supported Solid-Base Catalysts

   https://doi.org/10.1021/acsomega.8b01121  

   Liu, Chengyun ; Xin, Junna ; Tan, Jihuai ; Liu, Tuan ; Kessler, Michael R. ; Zhang, Jinwen ( August 2018 , ACS Omega)
5. Reevaluation of Poly(ethylene- alt -propylene)- block -Polydimethylsiloxane Phase Behavior Uncovers Topological Close-Packing and Epitaxial Quasicrystal Growth

   https://doi.org/10.1021/acsnano.1c02420  

   Lindsay, Aaron P. ; Jayaraman, Ashish ; Peterson, Austin J. ; Mueller, Andreas J. ; Weigand, Steven ; Almdal, Kristoffer ; Mahanthappa, Mahesh K. ; Lodge, Timothy P. ; Bates, Frank S. ( May 2021 , ACS Nano)

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