A5005423795- Fuel Cells and Related Materials
- Synthesis and properties of polymers
- Polymer composites and self-healing
- Advanced Polymer Synthesis and Characterization
- Polymer crystallization and properties
- Covalent Organic Framework Applications
- Supramolecular Self-Assembly in Materials
- Membrane-based Ion Separation Techniques
- Silicone and Siloxane Chemistry
- Dendrimers and Hyperbranched Polymers
- Advanced Battery Technologies Research
- Membrane Separation and Gas Transport
- Advanced Battery Materials and Technologies
- Supramolecular Chemistry and Complexes
- Polymer Nanocomposites and Properties
- RNA Interference and Gene Delivery
- Synthetic Organic Chemistry Methods
- Conducting polymers and applications
- Block Copolymer Self-Assembly
- Synthesis and Properties of Aromatic Compounds
- Probabilistic and Robust Engineering Design
- Dielectric materials and actuators
- Mechanical Behavior of Composites
- DNA and Nucleic Acid Chemistry
- Electrospun Nanofibers in Biomedical Applications
Virginia Tech
2014-2021
Interface (United States)
2014-2015
The ubiquitous biomacromolecule DNA has an axial rigidity persistence length of ~50 nm, driven by its elegant double helical structure. While and multiple helix structures appear widely in nature, only rarely are these found synthetic non-chiral macromolecules. Here we describe a conformation the densely charged aromatic polyamide poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) or PBDT. This macromolecule represents one most rigid simple molecular known, exhibiting extremely high (~1...
The supramolecular blend of complementary nucleobase-functionalized ABA triblock copolymers self-assemble into a microphase-separated morphology with enhanced mechanical performance and thermal responsiveness.
RAFT polymerization afforded acrylic ABC triblock copolymers with self-complementary nucleobase-functionalized external blocks and a low-<italic>T</italic><sub>g</sub> soft central block.
Two-step reversible addition–fragmentation chain transfer (RAFT) polymerization and two subsequent postpolymerization modification steps afforded well-defined ABA triblock copolymers featuring mechanically reinforcing polystyrene outer blocks 1-methylimidazole-neutralized poly(acrylic acid)-based central blocks. Size exclusion chromatography 1H NMR spectroscopy confirmed predictable molecular weights narrow distributions. The ionic liquid (IL) 1-ethyl-3-methylimidazolium...
Reversible addition–fragmentation chain transfer (RAFT) polymerization enabled the synthesis of well-defined A–BC–A triblock copolymers containing a synergy pendant ether and imidazolium sites.
Blocky sulfonated poly(ether ether ketone) (SPEEK) ionomers were synthesized by postpolymerization functionalization in the gel state. Matched sets of blocky and random SPEEK with ion contents between 3 11 mol % prepared, thermal transitions crystallization kinetics examined using differential scanning calorimetry (DSC). At similar contents, exhibited higher crystallizability faster than SPEEK. Reduced scattering contrast USAXS/SAXS/WAXD analysis copolymer membranes, relative to analogues,...
Blocky sulfonated syndiotactic polystyrene (SsPS) copolymers were produced using a recently developed postpolymerization functionalization procedure conducted in the gel state. The thermal properties and crystallization behavior of matched set blocky random SsPS containing 3 10 mol % sulfonate groups compared differential scanning calorimetry (DSC), which shows that architecture displays much faster rate even at low contents higher crystallizability high contents. glass transition...
A facile synthetic approach to segmented polysulfone-containing polyesters affords a versatile family of high-temperature thermoplastics with tunable thermomechanical properties. End-capping phenol-terminated polysulfone (PSU) using ethylene carbonate generated telechelic oligomers primary alcoholic functionality. Melt transesterification dimethyl terephthalate and 1,4-butanediol in the presence PSU yielded high molecular weight block copolymers alternating poly(butylene terephthalate) (PBT)...
Increasing hydrophobicity multiblock copolymers were synthesized by altering the copolymer composition of hydrophobic segments. A series nitrile-containing oligomers consisting bisphenol (Bis A), dimethylbisphenol (DMBPA), and tetramethylbisphenol (TMBPA) moieties reacted with a disulfonated poly (arylene ether sulfone) hydrophilic segment to form series. 1H 19F NMR spectroscopy used monitor progress copolymerization reactions confirm desired compositions. Membranes cast from resultant had...
The ability of a multiphase copolymer to exhibit both the physical properties liquid crystalline and elastomeric polymers enables variety emerging applications. Traditional synthetic methods often require many steps achieve such diversity in copolymer. This work describes synthesis characterization biphenyl-containing segmented copolyesters single step. A fundamental investigation thermal thermomechanical as function methylene spacer length demonstrates relationship between melting...
Two styrenic DABCO salt monomers allowed the synthesis of salt-containing random copolymers with two quaternized nitrogen cations on each ionic pendant group. Triethyl-(4-vinylbenzyl)ammonium chloride (VBTEACl) containing served as singly charged controls. 20 mol % or lower contents exhibited microphase-separated morphologies, agreeing multiplet-cluster model for ionomers. Thermomechanical and morphological analyses revealed that doubly salts promoted more well-defined microphase-separation...
Segmented polyurethanes based on poly(tetramethylene glycol) soft segments (SS) containing aromatic units are synthesized. Hydroquinone bis(2-hydroxyethyl) ether and 4,4′-methylenebis(phenyl isocyanate) used as the chain extender diisocyanate, respectively. Effects of incorporation hydroquinone (HQ) triptycene into morphology properties undeformed segmented investigated. Differential scanning calorimetry dynamic mechanical analysis indicate that leads to an increased glass transition...
Living anionic polymerization of 4-diphenylphosphino styrene (DPPS) achieved well-defined homopolymers, poly(DPPS-b-S) styrenic block copolymers, and poly(I-b-DPPS) diene-based diblock copolymers with predictable molecular weights narrow polydispersities. In situ FTIR spectroscopy monitored the DPPS tracked monomer consumption for kinetic analysis. Post-alkylation enabled controlled placement phosphonium functionality in producing phosphonium-containing low degrees compositional...
A facile synthesis of hydroxyethyl-functionalized poly(ether sulfone) (PESu) oligomers permitted subsequent melt transesterification into segmented block copolymers with poly(butylene terephthalate). The unique solubility the PESu in 1,4-butanediol and dimethyl terephthalate enabled a systematic study segment length on thermomechanical properties resulting copolymers. 1H NMR spectroscopy revealed compositional dependence average PBT. Additionally, concert spectroscopy, DSC, DMA highlighted...
Hydrogen bonding among nucleobase pairs serves as an efficient noncovalent interaction for designing supramolecular polymers with desired properties pressure sensitive adhesives. Michael addition yielded acetyl-protected cytosine/guanine containing acrylic monomers flexible spacers between the hydrogen units and backbone. Free radical polymerization of nucleobase-containing afforded homopolymers random copolymers n-butyl acrylate. Nucleobase incorporation significantly affected thermal,...
The ability to quickly develop predictions of the service lifetime plastic pipes at different load levels allows designers choose best material and design pipe for a specific application. Additionally, it helps producers rapidly design, manufacture, test, screen, modify base polymeric material. aim this study is introduce combined experimental analytical framework accelerated estimates semi‐crystalline which sensitive structure, orientation, morphology changes introduced by changing...
This study reports polyhedral oligomeric silsesquioxane (POSS)-based hybrid fibers of architectural hierarchy and compositional heterogeneity.
Living anionic polymerization of 4-diphenylphosphino styrene (DPPS) achieved unprecedented poly(S-b-I-b-DPPS) ABC triblock copolymers with predictable molecular weights and narrow polydispersities. In situ Fourier transform infrared spectroscopy probed the polymerization, monitoring vinyl disappearance during sequential monomer addition for kinetic analysis. Varying concentration reinforcing, polystyrenic external blocks enabled diverse compositions tunable thermomechanical properties...