Olsson, Joel S.; Pham, Thanh Huong; Jannasch, Patric
Poly(N,N-diallylazacycloalkane)s for Anion-Exchange Membranes Functionalized with N-Spirocyclic Quaternary Ammonium Cations
The alkaline stability of organic cations tethered to anion-exchange membranes (AEMs) is essential for the long-term performance of alkaline membrane fuel cells and electrolyzers. Here, we have prepared and studied the thermal and alkaline stability of a series of polyelectrolytes functionalized with N-spirocyclic quaternary ammonium (QA) cations. N,N-Diallylazacycloalkane quaternary salts…
Structural studies of thermally stable, combustion-resistant polymer composites
Smith, Gregory N.; Hallett, James E.; Joseph, Paul; Tretsiakova-McNally, Svetlana; Zhang, Tan; Blum, Frank D.; Eastoe, Julian
Composites of the industrially important polymer, poly(methyl methacrylate) (PMMA), were prepared by free-radical polymerization of MMA with varying amounts (1–30 wt. %) of sodium dioctylsulfosuccinate (Aerosol OT or AOT) surfactant added to the reaction mixture. The composites with AOT incorporated show enhanced resistance to thermal degradation compared to pure PMMA…
Comparative Investigation of the Thermoresponsive Behavior of Two Diblock Copolymers Comprising PNIPAM and PMDEGA Blocks
Aravopoulou, Dionysia; Kyriakos, Konstantinos; Miasnikova, Anna; Laschewsky, André; Papadakis, Christine M.; Kyritsis, Apostolos
The thermoresponsive behavior of two diblock copolymers PS-b-PNIPAM and PS-b-PMDEGA, which both comprise a hydrophobic polystyrene (PS) block but different thermoresponsive blocks, also differing in length, poly(N-isopropylacrylamide) (PNIPAM) and poly(methoxy diethylene glycol acrylate) (PMDEGA), respectively, was comparatively investigated in a wide temperature range. Concentrated aqueous…
High crystalline, porous polyamide 6 by anionic polymerization
Rahman, Md Arifur; Renna, Lawrence A.; Venkataraman, D.; Desbois, Philippe; Lesser, Alan J.
Polyamide 6 (PA6), also known as Nylon 6 is a widely used industrial polymer. The structural properties of PA6 play an important role in its potential commercial applications. We report that the anionic polymerization of ε-caprolactam in the presence of liquid additives such as o-Xylene, m-Xylene, p-Xylene and toluene at…
Understanding Thermal Insulation in Porous, Particulate Materials
Ruckdeschel, Pia; Philipp, Alexandra; Retsch, Markus
Silica hollow nanosphere colloidal crystals feature a uniquely well-defined structure across multiple length scales. This contribution elucidates the intricate interplay between structure and atmosphere on the effective thermal diffusivity as well as the effective thermal conductivity. Using silica hollow sphere assemblies, one can independently alter the particle geometry, the density,…
Bulk and Surface Morphologies of ABC Miktoarm Star Terpolymers Composed of PDMS, PI, and PMMA Arms
Chernyy, Sergey; Kirkensgaard, Jacob Judas Kain; Mahalik, Jyoti P.; Kim, Hyeyoung; Arras, Matthias M. L.; Kumar, Rajeev; Sumpter, Bobby G.; Smith, Gregory S.; Mortensen, Kell; Russell, Thomas P.; Almdal, Kristoffer
DIM miktoarm star copolymers, composed of polydimethylsiloxane , poly(1,4-isoprene) , and poly(methyl methacrylate) , were synthesized using a newly developed linking methodology with 4-allyl-1,1-diphenylethylene as a linking agent. The equilibrium bulk morphologies of the DIM stars were found to range from tiling patterns to alternating lamellar and alternating cylindrical…
Phase Behavior and Self-Assembly of Perfectly Sequence-Defined and Monodisperse Multiblock Copolypeptides
MacEwan, Sarah R.; Weitzhandler, Isaac; Hoffmann, Ingo; Genzer, Jan; Gradzielski, Michael; Chilkoti, Ashutosh
This paper investigates how the properties of multiblock copolypeptides can be tuned by their block architecture, defined by the size and distribution of blocks along the polymer chain. These parameters were explored by the precise, genetically encoded synthesis of recombinant elastin-like polypeptides (ELPs). A family of ELPs was synthesized in…
Poly(arylene piperidinium) Hydroxide Ion Exchange Membranes: Synthesis, Alkaline Stability, and Conductivity
Olsson, Joel S.; Pham, Thanh Huong; Jannasch, Patric
A series of poly(arylene piperidinium)s (PAPipQs) devoid of any alkali-sensitive aryl ether bonds or benzylic sites are prepared and studied as anion exchange membranes (AEMs) for alkaline fuel cells. First, the excellent alkaline stability of the model compound 4,4-diarylpiperidinium is confirmed. Medium molecular weight poly(arylene piperidine)s are then synthesized in…
Molecular Alignment in Polyethylene during Cold Drawing Using In-Situ SANS and Raman Spectroscopy
López-Barrón, Carlos R.; Zeng, Yiming; Schaefer, Jonathan J.; Eberle, Aaron P. R.; Lodge, Timothy P.; Bates, Frank S.
Changes in the crystalline and mesoscale lamellar structure during plastic deformation of semicrystalline polymers have been extensively studied by X-ray diffraction techniques. However, direct measurements of single chain conformations during stretching have not been realized, although they are key to fully understand the structural transitions during cold drawing and their…
Polystyrene-block-poly(ethylene oxide) Bottlebrush Block Copolymer Morphology Transitions: Influence of Side Chain Length and Volume Fraction
Gai, Yue; Song, Dong-Po; Yavitt, Benjamin M.; Watkins, James J.
A systematic study was conducted to investigate the morphology transitions that occur in polystyrene-block-poly(ethylene oxide) (PS-b-PEO) bottlebrush block copolymers (BBCP) upon varying PEO volume fraction (fPEO) from 22% to 81%. A series of PS-b-PEO BBCPs with different PEO side chain lengths were prepared using ring-opening metathesis polymerization (ROMP) of PEO–norbornene…