A5021121847- Advanced Polymer Synthesis and Characterization
- Block Copolymer Self-Assembly
- Surfactants and Colloidal Systems
- Rheology and Fluid Dynamics Studies
- Polymer crystallization and properties
- Ionic liquids properties and applications
- Material Dynamics and Properties
- Polymer Nanocomposites and Properties
- Conducting polymers and applications
- Polymer Surface Interaction Studies
- Advanced Battery Materials and Technologies
- Theoretical and Computational Physics
- Hydrogels: synthesis, properties, applications
- Advanced Sensor and Energy Harvesting Materials
- Machine Learning in Materials Science
- biodegradable polymer synthesis and properties
- Analytical Chemistry and Sensors
- RNA Interference and Gene Delivery
- Advanced Cellulose Research Studies
- Fuel Cells and Related Materials
- Polymer composites and self-healing
- Synthesis and properties of polymers
- Mesoporous Materials and Catalysis
- Supercapacitor Materials and Fabrication
- Adsorption, diffusion, and thermodynamic properties of materials
University of Minnesota
2016-2025
University of Minnesota System
1986-2025
National Institute of Standards
1983-2019
National Institute of Standards and Technology
1983-2019
Princeton University
2017-2018
Twin Cities Orthopedics
2005-2017
Minneapolis Institute of Arts
2015-2017
Yokohama National University
2009-2015
University of Warwick
2015
Eötvös Loránd University
2009
Advances in synthetic polymer chemistry have unleashed seemingly unlimited strategies for producing block polymers with arbitrary numbers (n) and types (k) of unique sequences repeating units. Increasing (k,n) leads to a geometric expansion possible molecular architectures, beyond conventional ABA-type triblock copolymers (k = 2, n 3), offering alluring opportunities generate exquisitely tailored materials unparalleled control over nanoscale-domain geometry, packing symmetry, chemical...
By combining three mutually immiscible polymeric components in a mixed-arm star block terpolymer architecture, we have observed the formation of previously unknown class multicompartment micelles dilute aqueous solution. Connection water-soluble poly(ethylene oxide) and two hydrophobic but (a hydrocarbon perfluorinated polyether) at common junction leads to molecular frustration when dispersed The incompatible blocks form cores that are protected from water by blocks, both forced make...
Abstract Here we summarize recent progress in the development of electrolyte‐gated transistors (EGTs) for organic and printed electronics. EGTs employ a high capacitance electrolyte as gate insulator; increases drive current, lowers operating voltages, enables new transistor architectures. Although use electrolytes electronics is an old concept going back to early days silicon transistor, printable, fast‐response polymer are expanding potential applications flexible, digital circuits,...
Janus Drug Delivery Vehicle Efficient drug delivery vehicles need to be produced in a limited size range and with uniform distribution. The self-assembly of traditional small-molecule polymeric amphiphiles has led the production micelles, liposomes, polymersomes for use applications. Now, Percec et al. (p. 1009 ) describe Janus-type (i.e., two-headed) dendrimers produce monodisperse supramolecular constructs, termed “dendrimersomes,” other complex architectures. structures, which showed...
In a miscible polymer blend the local environment of monomer type A will, on average, be rich in compared to bulk composition, φ, and similarly for B; this is direct consequence chain connectivity. As result, dynamics two chains may exhibit different dependences temperature overall composition. By assigning length scale (or volume) particular dynamic mode, relevant “self-concentration” φs can estimated. For example, we associate Kuhn chain, lK, with monomeric friction factor, ζ, thus...
Abstract Block copolymers are the focus of a great deal research activity in contemporary macromolecular science. This is attributable to range fascinating fundamental issues associated with understanding self‐assembly processes both solution and bulk, coupled an adventitious convergence substantial progress synthetic versatility, developments molecular structural characterization, factors that control phase behavior, elucidation response copolymer materials external fields. It argued due...
Multicompartment micelles are an intriguing class of self-assembled aggregates with subdivided solvophobic cores. They have been subject to extensive research in part due their unique morphological and sequestration properties as a result multiple distinct chemical environments being close proximity within one nanostructure. hold potential for use various applications that include the therapeutic delivery incompatible drug payloads. The present Perspective reviews recent achievements...
We have fabricated polymer semiconductor thin-film transistors using an ion gel (ionic liquid plus triblock copolymer) as the gate dielectric layer. The capacitance of can be large 40 μF/cm2 at 10 Hz and 2 1 kHz. In addition, polarization response time is much faster than previously tested solid electrolytes, allowing gated to operate higher frequencies (>100 Hz).
A free-standing polymer electrolyte called an ion gel is employed in both organic and inorganic thin-film transistors as a high capacitance gate dielectric. To prepare transistor, the simply laid over semiconductor channel side-gate electrode, which possible because of gel's mechanical strength.
By combining ionic liquids with block polymers, a virtually unlimited range of composite materials can be prepared.
Four amphiphilic poly((1,2-butadiene)-block-ethylene oxide) (PB−PEO) diblock copolymers were shown to aggregate strongly and form micelles in an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]). The universal micellar structures (spherical micelle, wormlike bilayered vesicle) all accessed by varying the length of corona block while holding core constant. nanostructures PB−PEO formed liquid directly visualized cryogenic transmission electron microscopy (cryo-TEM)....
The phase behavior of six poly(styrene-b-isoprene) (SI) diblock copolymers has been mapped out in the styrene-selective solvents di-n-butyl phthalate (DBP), diethyl (DEP), and dimethyl (DMP). polymer molecular weights were chosen to make melt order−disorder transition (ODT) experimentally accessible, styrene compositions f ranged from 0.23 0.70, access full range morphologies. For each a diagram was constructed, with volume fractions, φ, ranging 0.01 1.0 temperatures, T, 0 250 °C. Phase...
The use of an ion gel as the gate insulator in polymer TFTs is described. composed ionic liquid and a triblock copolymer, provides very large specific capacitance, which allows both low voltage operation high transconductance. Ion-gel-gated can be switched at rate 1 kHz response time strongly correlated to conductivity.
We report comprehensive characterization of electrolyte-gated polymer thin-film transistors (TFTs) incorporating solution processable semiconductors and high capacitance "ion gel" gate dielectrics. The ion gel dielectrics comprise self-assembled networks triblock copolymers such as poly(styrene-b-methylmethacrylate-b-styrene) [PS-PMMA-PS] that are swollen with ionic liquids, e.g., (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]). the gels is exceptionally large...
A "cluster-bomb"-like lipid–dendrimer nanoassembly synergizes the functions of its components and thereby efficiently accomplishes drug delivery cascade for high efficacy in treating cancer. The successfully circulates blood accumulates tumor. Once tumor, it releases small dendrimers that act like "bomblets", enabling tumor penetration, cell internalization, release. Cancer nanomedicine is regarded as one few strategies may revolutionize cancer treatments.1 Several nanomedicines such DOXIL...
The primary challenge in solid-state polymer electrolyte membranes (PEMs) is to enhance properties, such as modulus, toughness, and high temperature stability, without sacrificing ionic conductivity. We report a remarkably facile one-pot synthetic strategy based on polymerization-induced phase separation (PIPS) generate nanostructured PEMs that exhibit an unprecedented combination of modulus Simple heating poly(ethylene oxide) macromolecular chain transfer agent dissolved mixture liquid,...
The functionality of ion gels can be enhanced by incorporating different types redox-active species. Here, we have expanded the composed polystyrene-block-poly(methyl methacrylate)-block-polystyrene and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide to include electrochromism adding an electrochromic (EC) redox molecule, methyl viologen. Ferrocene was also added EC gel as anodic inserted between two indium–tin oxide-coated glass slides (or plastic sheets) make a simple...
Ion gels composed of a copolymer and room temperature ionic liquid are versatile solid-state electrolytes with excellent features including high conductivity, nonvolatility, easily tunable mechanical properties, good flexibility solution processability. can be functionalized by incorporating redox-active species such as electrochemiluminescent (ECL) luminophores or electrochromic (EC) dyes. Here, we enhance the functionality EC for realizing multicolored devices (ECDs), either controlling...
Ion gels comprising ABA triblock copolymers and ionic liquids have received much attention as functional materials in numerous applications, especially gate dielectrics organic transistors. Here we expanded the functionality of ion by demonstrating low-voltage, flexible electrochemiluminescent (ECL) devices using patterned containing redox-active luminophores. The ECL consisted only a 30 μm thick emissive gel two electrodes were fabricated on indium tin oxide-coated substrates (e.g.,...
The effect of the thermodynamic selectivity a solvent on self-assembly styrene−isoprene (SI) diblock copolymer with block molecular weights 1.1 × 104 and 2.1 g/mol is investigated. We explore phase behavior from melt state to dilute solution in solvents that are varying selectivities for two blocks. Bis(2-ethylhexyl) phthalate (DOP) neutral good SI. Di-n-butyl (DBP) diethyl (DEP) PS but marginal poor, respectively, PI. Tetradecane (C14) utilized as complementary PI poor PS. Small-angle X-ray...
The thermoreversible gelation of methylcellulose in aqueous solution has been studied by static and dynamic light scattering (DLS), small-angle neutron (SANS), rheology. At 20 °C, dilute establishes the molecular weight, second virial coefficient, radius gyration, hydrodynamic polymer. Semidilute solutions exhibit two relaxation modes DLS, one reflecting cooperative diffusion other attributable to pregel clusters. Rheological measurements this regime also suggest a weak supermolecular...
High molecular weight block copolymers can be viewed as macromolecular surfactants when blended with thermodynamically incompatible homopolymers. This Letter describes the formation of polymeric bicontinuous microemulsions in mixtures containing a model diblock copolymer and two Although we attribute development this equilibrium morphology to effects fluctuations, mean-field theory provides quantitative strategy for preparing state at blend compositions near an isotropic Lifshitz point.