نتایج جستجو برای: polymers
تعداد نتایج: 71001 فیلتر نتایج به سال:
A new class of aryl trifluorovinyl ether monomers were designed and synthesized, and novel fluorinated polymers containing perfluorocyclobutane and 1H-1,2,3-triazole units were prepared from these monomers. These polymers were characterized by nuclear magnetic resonance spectroscopy, thermo-gravimetric analysis and differential scanning calorimetry. The temperatures of 5% weight loss of the pol...
The novel boron-chelated π-conjugated polymers named as BF2-poly and BPh2-poly were synthesized by a feasible condensation-chelation strategy. First, conjugated polymers bearing Boc group were prepared by using palladium-catalyzed Suzuki–Miyaura coupling reaction. Then, conjugated polymers (poly-1) were obtained with high efficiency by removing the Boc group from Boc-poly. Last, boron trifluori...
Many cytoskeletal biopolymers are "active," consuming energy in large quantities. In this Letter, we identify a fundamental difference between active polymers and passive, equilibrium polymers: for equal mean lengths, active polymers can reorganize faster than equilibrium polymers. We show that equilibrium polymers are intrinsically limited to linear scaling between mean lifetime (or mean first...
Targeted delivery of anticancer therapeutics can potentially overcome the limitations associated with current chemotherapeutic regimens. Folate receptors are overexpressed in several cancers, including ovarian, triple-negative breast and bladder cancers, making them attractive for targeted delivery of nucleic acid therapeutics to these tumors. This work describes the synthesis, characterization...
A simple analytic theory for mixtures of hard spheres and larger polymers with excluded volume interactions is developed. The mixture is shown to exhibit extensive immiscibility. For large polymers with strong excluded volume interactions, the density of monomers at the critical point for demixing decreases as one over the square root of the length of the polymer, while the density of spheres t...
We analyze van der Waals interactions between two rigid polymers with sequence-specific, anisotropic polarizabilities along the polymer backbones, so that the dipole moments fluctuate parallel to the polymer backbones. Assuming that each polymer has a quenched-in polarizability sequence which reflects, for example, the polynucleotide sequence of a double-stranded DNA molecule, we study the van ...
New high performance polymers have been developed that challenge traditional encapsulation materials for permanent active medical implants. The gold standard for hermetic encapsulation for implants is a titanium enclosure which is sealed using laser welding. Polymers may be an alternative encapsulation material. Although many polymers are biocompatible, and permeability of polymers may be reduc...
Water-soluble hydrophobically associating polymers are examined with particular emphasis on their rheology for oilfield applications. The incorporation of a small amount (less than 1 mol%) of hydrophobic groups into the polymer backbone of a water-soluble polymer dramatically alters the rheological properties of the resulting material. Associating polymers have potential for use in mobility con...
Polyurethanes are the most well known polymers used to make a binder in high energy material. Polyurethanes aregenerally synthesized by the reaction of diisocyanates and polyols and chain extender.These polymers are often two-phase morphology.Chain extenders are small diols or diamines that are inserted to the hard segment of of polyurethane chain. chemical structure of chain extender, the ...
Over the past 25 years many interesting biomedical uses have been proposed for stimuli-responsive polymers, including uses in diagnostics, drug delivery, tissue engineering (regenerative medicine), and cell culture. This article briefly overviews the field of stimuli-responsive polymers and describes some of the most successful biomedical applications to date of such "smart" polymers. Other int...
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