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The physical mechanisms underlining the unique shape memory behavior in polymers differ greatly from those in intermetallics. However, phenomenologically, both material systems exhibit pseudoplasticity and superelasticity. This provides the main motivation for the present work, in which a recently-developed multi-mechanism model, previously used successfully for intermetallics is extended to capture...
This paper describes the feasibility of achieving melt-processable polyacrylonitrile copolymer precursors for producing high strength carbon fibers. High molecular weight poly(acrylonitrile-ran-methyl acrylate) (PAN-MA) copolymers with high acrylonitrile content were mixed were various binary melting point modifiers with one component being water to produce systems that formed stable melts at temperatures...
Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) is utilized for gas separation membranes. It has a relatively high free volume with high gas permeabilities but suffers from low selectivities. PPO polymers with Mn's from 2000 to 22,000 g/mole were synthesized and blended with a poly(arylene ether ketone) derived from bisphenol A and difluorobenzophenone (BPA-PAEK). DSC showed that the blends with all...
Modification of membranes to improve gas separation properties has been of considerable interest. Crosslinking is one route to modify membranes, but such studies need to be performed on thin membranes to quantify the impact of such modifications at thicknesses relevant to industrial membranes. In this study, the influences of UV irradiation and physical aging on O2 and N2 gas permeation properties...
There is a need for polymeric capacitors with improved energy storage density and thermal stability. In this work, the effect of polymer molecular structure and symmetry on Tg, breakdown strength, and relative permittivity were investigated. A systematic series of four amorphous poly(arylene ether ketone)s were compared. Two of the polymers had symmetric bisphenols while the remaining two had asymmetric...
A series of polybenzimidazoles containing sulfonyl groups were synthesized in Eaton's reagent for high temperature H2/CO2 separation membranes. The key monomer, 3,3′,4,4′-tetraaminodiphenylsulfone, was prepared via a novel and economical synthetic route starting from 4,4′-dichlorodiphenylsulfone. These polybenzimidazoles with sulfonyl moieties had enhanced solubilities in dipolar aprotic solvents...
Alkylacrylamide phosphonate monomers were synthesized by aza-Michael addition of an alkylamine onto the double bond of diethyl vinylphosphonate, then reaction with acryloyl chloride. Free radical copolymerization of n-butylacrylamide phosphonate with an acrylate-functional PEO macromonomer, then removal of the ethyl groups from the phosphonates led to poly(n-butylacrylamide phosphonic acid)-g-PEO...
The time-temperature superposition property of an amorphous polymer acrylate network is characterized at infinitesimal strain by standard dynamic mechanical analysis tests. Comparison of the shift factors determined in uniaxial tension and in torsion shows that both tests provide equivalent time-temperature superposition properties. More interestingly, finite strain uniaxial tension tests run until...
Control over molecular weight distribution and endgroup functionality is important for prepolymers that are to be further incorporated into block and graft copolymers. Monofunctional, telechelic and heterobifunctional poly(2-ethyl-2-oxazoline) (PEtOx) oligomers were prepared by cationic ring-opening polymerization with different classes of initiators including methyl triflate as the control, activated...
Ammonium bisdiethylphosphonate acrylate and methacrylate monomers were synthesized by an aza-Michael addition of 3-aminopropanol across the double bond of bisdiethylphosphonate, followed by acylation with (meth)acryloyl chloride. Free radical copolymerizations of the monomers with an acrylate-functional poly(ethylene oxide) (PEO) macromonomer produced graft copolymers. Quantitative deprotection of...
High-energy irradiations of polymers may cause bond cleavage or crosslinking and change the structures and physical properties of the polymers, which may offer various applications. Despite wide investigation, relationship between the kinetics and mechanism of annihilation after irradiations and the structure and some physical properties of irradiated polymers is still poorly established. We have...
Amphiphilic triblock poly(2-ethyl-2-oxazoline-b-sulfone-b-2-ethyl-2-oxazoline) (PEOX-b-PSF-b-PEOX) and poly(2-ethyl-2-oxazoline-co-ethyleneimine-b-sulfone-b-2-ethyl-2-oxazoline-co-ethyleneimine) (PEOXcoPEI-b-PSF-b-PEOXcoPEI) copolymers were synthesized for potential use as water purification membranes. Poly(arylene ether sulfone) (polysulfone) oligomers of controlled molecular weight were prepared...
A combination of spontaneous reactive chemical domains bounded by non-fouling zones provides a means to covalently immobilize biomolecules in structured, spatially defined arrays. These arrays have application in a wide range of biotechnologies including tissue engineering, proteomics, and diagnostics. In this paper, we describe the fabrication of multi-chemistry micropatterns from plasma polymers...
The mechanical properties of artists’ acrylic (latex) paint films containing different volume fractions of TiO 2 , CaCO 3 and kaolin were measured in uni-axial tension over a broad range of temperatures and crosshead speeds. Young’s modulus results in the glassy region were first compared with several micromechanics theories for particle-filled composites containing elastic phases...
Polymer–magnetite nanoparticle complexes that respond to both magnetic fields and to temperature have been demonstrated. Novel alkyl halide-functional bis(diethylphosphonate) esters were prepared and utilized as initiators for polymerizing N-isopropylacrylamide by controlled atom transfer radical polymerization. The phosphonate esters were removed after polymerization to afford poly(N-isopropylacrylamide)...
Magnetic nanoparticles have numerous applications, particularly in biological systems for drug delivery, cell targeting, and as MRI contrast agents. This paper addresses the synthesis and characterization of well-defined magnetite nanoparticles coated with tricarboxylate-functional polydimethylsiloxane (PDMS) oligomers of varying molecular weight. Two methods – co-precipitation of iron chlorides and...
Polymers that exhibit an affinity to metal ions are important for separation science and sensor applications. In this paper, we describe the creation of surface micropatterns with three plasma polymers, acrylic acid (ppAAc), allylamine (ppAAm) and tetraglyme (ppTG). Time-of-Flight Static Secondary Ion Mass Spectrometry (ToF-SSIMS) imaging has been used to visualise the chemical specificity and selectivity...
Microcapsules containing a solvent and reactive epoxy resin are a critical component for the development of cost-effective, low toxicity, and low flammability self-healing materials. We report a robust in situ encapsulation method for protection of a variety of oil soluble solvents and reactive epoxy resins surrounded by a thin, polymeric, urea–formaldehyde (UF) shell. Resin–solvent capsules are produced...
Poly(lactide-b-siloxane-b-lactide) triblock copolymers with pendent carboxylate groups have been synthesized to serve as dispersants for magnetite nanoparticles. Magnetic nanoparticles are of interest for potential biomedical applications including magnetic field-directed drug delivery and magnetic cell separations. For in-vivo applications, it is important that the magnetic particle be coated with...
Single electrospinning jets are known to have low production rates. A 0.1m 2 nonwoven mat containing 1g of 100nm fibers may take several days to create from a single jet. Inexpensive methods of higher production rates are needed for laboratory research applications. In this paper we present experimental results of many simultaneous electrospinning jets from the surface of tube having a porous...
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