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Articles 1 - 15 of 15
Full-Text Articles in Engineering
Impact Of Homopolymer Pore Expander On The Morphology Of Mesoporous Carbon Films Using Organic--Organic Self-Assembly, Alpha Labiano, Mingzhi Dai, Wen-Shiue Young, Gilia Stein, Kevin Cavicchi, Thomas Epps, Bryan Vogt
Impact Of Homopolymer Pore Expander On The Morphology Of Mesoporous Carbon Films Using Organic--Organic Self-Assembly, Alpha Labiano, Mingzhi Dai, Wen-Shiue Young, Gilia Stein, Kevin Cavicchi, Thomas Epps, Bryan Vogt
Kevin Cavicchi
Soft templated mesoporous carbon films (ca. 60 nm thick) are fabricated by the cooperative assembly of poly(styrene-block-ethylene oxide) (PS-b-PEO) with phenolic resin, where the pore sizes are tuned by the addition of polystyrene oligomers (hPS) to this self-assembling system. Significant differences in the morphology and pore expansion are found for the thin films in comparison to previously reported bulk powders using a similar system. The film porosity is nearly independent of swelling agent content for addition of up to 10 wt % hPS; this limited effect is attributed to surface segregation of the hPS on the basis of wetting considerations, …
Synthesis Of Poly (Trioctylammonium P-Styrenesulfonate) Homopolymers And Block Copolymers By Raft Polymerization, Yuqing Liu, Kevin Pollock, Kevin Cavicchi
Synthesis Of Poly (Trioctylammonium P-Styrenesulfonate) Homopolymers And Block Copolymers By Raft Polymerization, Yuqing Liu, Kevin Pollock, Kevin Cavicchi
Kevin Cavicchi
A method to prepare sulfonated polystyrene-containing block copolymers has been investigated by neutralizing styrene sulfonic acid with trioctylamine to produce the hydrophobic monomer trioctylammonium p-styrenesulfonate (SS–TOA). This monomer was polymerized by reversible addition fragmentation chain transfer (RAFT) polymerization to produce PSS–TOA homopolymers. A PSS–TOA homopolymer was then used as a macro-RAFT agent for the polymerization of styrene to prepare poly(trioctylammonium p-styrenesulfonate)-block-poly(styrene) (PSS-TOA-b-PS). These block copolymers could be ion-exchanged to produce either the hydrophilic sodium salt form of PSS or a hydrophobic quaternary ammonium salt. This approach will be useful for preparing PSS-containing block copolymers with a range of hydrophobic blocks …
Investigation Of The Relationships Between The Thermodynamic Phase Behavior And Gelation Behavior Of A Series Of Tripodal Trisamide Compounds, Li Feng, Kevin Cavicchi
Investigation Of The Relationships Between The Thermodynamic Phase Behavior And Gelation Behavior Of A Series Of Tripodal Trisamide Compounds, Li Feng, Kevin Cavicchi
Kevin Cavicchi
The solution behavior of a series of tris(2-aminoethyl)amine (TREN) based trisamide derivatives in organic solutions was investigated with a focus on organogelation. First, the general solution behavior of eight compounds was investigated and qualitatively interpreted using the regular solution model and solubility parameter theory. Second, the phase behavior of one trisamide in aromatic solvents, where gels were formed, was investigated in more detail. A correlation was found between the sol–gel transition temperature and the thermodynamic liquidus lines. The prediction of the liquidus lines using the regular solution model and solubility parameter theory reproduced the shape and scaling of the gel …
Synthesis And Polymerization Of Substituted Ammonium Sulfonate Monomers For Advanced Materials Applications, Kevin Cavicchi
Synthesis And Polymerization Of Substituted Ammonium Sulfonate Monomers For Advanced Materials Applications, Kevin Cavicchi
Kevin Cavicchi
Sulfonated polymers have found use as ion-exchange membranes for use in fuel cells, water purification, electroactive devices, and inorganic materials templating and synthesis. Improving the materials for these applications and opening up new applications requires the ability to synthesis targeted or more complex sulfonated polymers, which includes tailoring the chemistry (copolymerization across a wider range of solubility) and/or polymer architecture (block, graft, nanoparticle). This article will summarize the recent work using sulfonated monomers with substituted ammonium counterions as a versatile route for enabling this goal. Two main benefits of these monomers are as follows. First, they are useful for preparing …
Reversible Addition Fragmentation Chain Transfer (Raft) Polymerization With A Polymeric Raft Agent Containing Multiple Trithiocarbonate Groups, Kevin Cavicchi, Yuqing Liu
Reversible Addition Fragmentation Chain Transfer (Raft) Polymerization With A Polymeric Raft Agent Containing Multiple Trithiocarbonate Groups, Kevin Cavicchi, Yuqing Liu
Kevin Cavicchi
Polytrithiocarbonates were prepared by the condensation polymerization of a dicarboxylic acid functional trithiocarbonate and a diol. These polymers were effective reversible addition fragmentation chain transfer (RAFT) agents for the bulk polymerization of polystyrene homopolymers and a poly[styrene-block-(tert-butylstyrene)] block copolymer. Size exclusion chromatography (SEC) analysis of the original and amine cleaved polymers showed that the polydispersity of the polymer tended toward two with increasing polymerization time, but the polydispersity of the polymer units between trithiocarbonate groups was narrow (ca. 1.1–1.3) Also, the average number of trithiocarbonate groups per chain was found to be proportional to the number of trithiocarbonate groups in …
Synthesis And Characterization Of Novel Comb-Type Amphiphilic Graft Copolymers Containing Polypropylene And Polyethylene Glycol, Murat Balci, Abdulkadir Alli, Baki Hazer, Olgun Guven, Kevin Cavicchi, Mukerrem Cakmak
Synthesis And Characterization Of Novel Comb-Type Amphiphilic Graft Copolymers Containing Polypropylene And Polyethylene Glycol, Murat Balci, Abdulkadir Alli, Baki Hazer, Olgun Guven, Kevin Cavicchi, Mukerrem Cakmak
Kevin Cavicchi
Amphiphilic comb-type graft copolymers containing polypropylene (PP) and polyethylene glycol (PEG) have been prepared. Polypropylene-g-polyethylene glycol comb-type thermoplastic amphiphilic copolymers were synthesized by the reaction between chlorinated polypropylene and polyethylene glycol in the presence of a base via a “grafting to” technique. A series of graft copolymers containing PEGs with molecular weights of 600 and 2,000 Da in the range of 4–34 mol% PEG were obtained. The amphiphilic graft copolymers with PEG segments in range between 20 and 30 mol% PEG displayed good film properties with elongation at break 275–440%. The hydrophilicity of the amphiphilic copolymers increases with the increasing …
Polyelectrolyte--Surfactant Complexes As Thermoreversible Organogelators, Yuqing Liu, Ashley Lloyd, Gustavo Guzman, Kevin Cavicchi
Polyelectrolyte--Surfactant Complexes As Thermoreversible Organogelators, Yuqing Liu, Ashley Lloyd, Gustavo Guzman, Kevin Cavicchi
Kevin Cavicchi
Poly(N,N-dimethyl-n-octadecylammonium p-styrenesulfonate) (PSS-DMODA) polymers were prepared and investigated as organogelators for low-polarity aromatic solvents. Gels were prepared by heating polymer solutions (2.5–20% w/v polymer) at elevated temperature and then cooling in an ice bath. Gelation was confirmed by the formation of self-supporting samples that did not flow when inverted 180°. Measurement of the gel transition temperature by inversion testing showed a dependence on the concentration of the polymer, the molecular weight of the polymer, and the gelled solvent. Cavitation rheology measurements on a subset of the gels demonstrated that they were viscoelastic solids. Scanning electron microscopy measurements of freeze-dried xerogels …
Imaging Magnetic Flux Lines With Iron Oxide Nanoparticles Using A Fossilized Liquid Assembly, Ryan Schmidt, Jason Benkoski, Kevin Cavicchi, Alamgir Karim
Imaging Magnetic Flux Lines With Iron Oxide Nanoparticles Using A Fossilized Liquid Assembly, Ryan Schmidt, Jason Benkoski, Kevin Cavicchi, Alamgir Karim
Kevin Cavicchi
Directed self-assembly of nanomaterials via external fields is an attractive processing tool for industry as it is inherently inexpensive and flexible. Direct observations of this process are however challenging due to the nano and meso length scales involved. The self-assembly of magnetic nanoparticles in particular has gained much recent interest for applications ranging from biomedical imaging and targeted cancer therapy to ferrofluid mechanical damping devices, that rely on the state of aggregation and alignment of the nanoparticles. We utilize an oil–water platform to directly observe directed self-assembly of magnetic nanoparticles that are field ordered into two-dimensional mesostructures through the fossilized …
Solvent Dependence Of The Morphology Of Spin-Coated Thin Films Of Polydimethylsiloxane-Rich Polystyrene-Block-Polydimethylsiloxane Copolymers, Maurice Wadley, I-Fan Hsieh, Kevin Cavicchi, Stephen Cheng
Solvent Dependence Of The Morphology Of Spin-Coated Thin Films Of Polydimethylsiloxane-Rich Polystyrene-Block-Polydimethylsiloxane Copolymers, Maurice Wadley, I-Fan Hsieh, Kevin Cavicchi, Stephen Cheng
Kevin Cavicchi
The as-spun, thin film morphologies of a series polydimethylsiloxane-rich cylinder and lamellar-forming polystyrene-block-polydimethylsiloxane (PS-b-PDMS) copolymers with constant PDMS molecular weight and varying PS volume fraction were studied with a range of solvents of varying solubility parameter. It was found that PDMS occupies the surface of the thin films regardless of the choice of solvent used in spin-coating due to its extremely low surface tension. The morphology shifted from parallel cylinders to hexagonally perforated lamellar to parallel lamellar as the solvent was varied from PDMS to PS selective solvents (increasing solvent solubility parameter). The transition points between each morphology were also …
Control Over Self-Assembly Of Diblock Copolymers On Hexagonal And Square Templates For High Area Density Circuit Boards, Jie Feng, Kevin Cavicchi, Hendrik Heinz
Control Over Self-Assembly Of Diblock Copolymers On Hexagonal And Square Templates For High Area Density Circuit Boards, Jie Feng, Kevin Cavicchi, Hendrik Heinz
Kevin Cavicchi
Self-assembled diblock copolymer melts on patterned substrates can induce a smaller characteristic domain spacing compared to predefined lithographic patterns and enable the manufacture of circuit boards with a high area density of computing and storage units. Monte Carlo simulation using coarse-grain models of polystyrene-b-polydimethylsiloxane shows that the generation of high-density hexagonal and square patterns is controlled by the ratio ND of the surface area per post and the surface area per spherical domain of neat block copolymer. ND represents the preferred number of block copolymer domains per post. Selected integer numbers support the formation of ordered structures on hexagonal (1, …
Phase Structural Formation And Oscillation In Polystyrene-Block-Polydimethylsiloxane Thin Films, I-Fan Hsieh, Hao-Jan Sun, Qiang Fu, Bernard Lotz, Kevin Cavicchi, Stephen Cheng
Phase Structural Formation And Oscillation In Polystyrene-Block-Polydimethylsiloxane Thin Films, I-Fan Hsieh, Hao-Jan Sun, Qiang Fu, Bernard Lotz, Kevin Cavicchi, Stephen Cheng
Kevin Cavicchi
The solvent-induced spherical structure in a polystyrene-block-polydimethylsiloxane (PS-b-PDMS) block copolymer was obtained and stabilized by preparing both the bulk and thin films from propylene glycol methyl ether acetate (PGMEA) solutions. The diblock copolymer possessed a total molecular weight of 42 kDa with a PS volume fraction of 72.2%, and it formed a cylindrical phase structure in the equilibrium bulk state. During thermal annealing, only changes in the sphere size and packing rearrangement were found. In contrast, a unique structure evolution route was observed during solvent treatments. Under a controlled vapour of a PS selective solvent, an oscillation of the structural …
An Ordered Nanoporous Monolith From An Elastomeric Crosslinked Block Copolymer Precursor, Kevin Cavicchi
An Ordered Nanoporous Monolith From An Elastomeric Crosslinked Block Copolymer Precursor, Kevin Cavicchi
Kevin Cavicchi
An ordered nanoporous monolith was prepared from a poly(isoprene-b-dimethylsiloxane) (PI-PDMS) hexagonally packed cylinder precursor. The PDMS cylinders were macroscopically aligned, the PI was crosslinked with dicumyl peroxide, and the PDMS was removed using tetrabutylammonium fluoride. The stability of the pores depended on the modulus of the matrix. At high crosslink density the pores were stable, but they collapsed at a low crosslink density. The nanoporous materials could be swollen in toluene.
Synthesis Of Polydimethylsiloxane-Containing Block Copolymers Via Reversible Addition Fragmentation Chain Transfer (Raft) Polymerization, Maurice Wadley, Kevin Cavicchi
Synthesis Of Polydimethylsiloxane-Containing Block Copolymers Via Reversible Addition Fragmentation Chain Transfer (Raft) Polymerization, Maurice Wadley, Kevin Cavicchi
Kevin Cavicchi
Low polydispersity polydimethylsiloxane (PDMS) was end functionalized with a reversible addition fragmentation chain transfer (RAFT) agent by the esterification of hydroxyl terminated PDMS with a carboxylic acid functional RAFT agent. These PDMS-RAFT agents were able to control the free radical polymerization of styrene and substituted styrene monomers to produce PDMS-containing block copolymers with low polydispersities and targeted molecular weights. A thin film of polydimethylsiloxane-block-polystyrene was prepared by spin coating and exhibited a microphase separated morphology from scanning force microscopy measurements. Controlled swelling of these films in solvent vapor produced morphologies with significant long-range order. This synthetic route will allow the …
Synthesis, Characterization, And Antibacterial Activity Of Metal Nanoparticles Embedded Into Amphiphilic Comb-Type Graft Copolymers, Ozlem Kalayci, Fusun Comert, Baki Hazer, Turgay Atalay, Kevin Cavicchi, Mukerrem Cakmak
Synthesis, Characterization, And Antibacterial Activity Of Metal Nanoparticles Embedded Into Amphiphilic Comb-Type Graft Copolymers, Ozlem Kalayci, Fusun Comert, Baki Hazer, Turgay Atalay, Kevin Cavicchi, Mukerrem Cakmak
Kevin Cavicchi
The synthesis, spectroscopic characterization, and antimicrobial efficiency of gold and silver nanoparticles embedded in novel amphiphilic comb-type graft copolymers having good film-forming properties have been described. Amphiphilic comb-type graft copolymers were synthesized by the reaction of chlorinated polypropylene (PP) (M w = 140,000 Da) with polyethylene glycol (PEG) (M n = 2,000 Da) at different molar ratios. Metal nanoparticles embedded graft copolymers were prepared by reducing solutions of the salts of silver or gold and the copolymer in tetrahydrofuran. The optical properties of the metal nanoparticle embedded copolymers were determined by using UV–visible spectroscopy. Surface plasmon resonance (SPR) of the …
Synthesis And Characterization Of A Poly (Styrene-Block-Methylacrylate-Random-Octadecylacrylate-Block-Styrene) Shape Memory Aba Triblock Copolymer, Pengzhan Fei, Kevin Cavicchi
Synthesis And Characterization Of A Poly (Styrene-Block-Methylacrylate-Random-Octadecylacrylate-Block-Styrene) Shape Memory Aba Triblock Copolymer, Pengzhan Fei, Kevin Cavicchi
Kevin Cavicchi
A new shape memory polymer (SMP) was prepared from an ABA triblock copolymer with polystyrene (PS) end blocks and a random copolymer midblock of poly(methylacrylate-random-octadecylacrylate) (PMA-r-PODA). The self-assembly of the triblock copolymer generates a three-dimensional, physically cross-linked network by the bridging of the midblocks across the glassy PS domains, which is used as the permanent network in the SMP. A second reversible network is generated by the side-chain crystallization of the PODA side-chains. Shape memory testing by uniaxial deformation and recovery of molded tensile bars demonstrated that shape fixities greater than 96% and shape recoveries greater than 98% were obtained …