PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Fluorocarbon Polymers”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22Linked to original sources
PubMed1997

Heterogeneous nucleation of calcium phosphates on solid surfaces in aqueous solution.

The heterogeneous nucleation of calcium phosphates on solid surfaces of poly(methyl methacrylate) (PMMA), poly-(tetrafluoroethylene-co-hexafluoropropylene) (FEP), silicone rubber, mica, and radiofrequency glow discharge (RFGD)-treated PMMA, FEP, and silicone rubber has been studied in solutions supersaturated with respect to hydroxyapatite. The surface properties of the substrates were characterized by contact angle measurements. For the RFGD-treated surfaces, the Lifshitz-Van der Waals surface tension component changes very little, but the Lewis acid-base surface tension parameters vary greatly depending upon the materials. With scanning electron microscopy, nucleation of calcium phosphates was observed only on the surfaces: mica, RFGD-treated PMMA and FEP, with relatively high values of the Lewis base surface tension parameter. The more hydrophobic surfaces having low Lewis acid-base surface tensions, untreated PMMA and FEP, silicone rubber, and even RFGD-treated silicone rubber showed no nucleation.

Biocompatible Materials↗
PubMed1998

Identification and quantification of the crystalline structures of poly(vinylidene fluoride) sutures by wide-angle X-ray scattering and differential scanning calorimetry.

The outstanding biocompatibility of the polyvinylidene fluoride (PVDF) monofilament suture together with other desirable characteristics, such as ease of handling and resistance to biodegradation, makes it an attractive alternative monofilament suture material for cardiovascular surgery. However, to achieve a high performance suture, the polymeric raw material must be exposed to different treatments, which lead to different degrees and types of crystallization. Since these crystalline modifications deeply influence the mechanical characteristics and the biostability of the sutures, the authors hereby propose a method of quantifying the different structures of PVDF using wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The commercial devices are achieved by coloring and processing the polymeric raw material. The white and unprocessed 4-0 unswaged suture presents 19% of the alpha phase, 38% of the beta structure, and no gamma form. Coloration increases the amount of the beta phase by 5-9% at the expense of the alpha phase. On the other hand, processing the fibers lead to the conversion of some of the amorphous phase to the gamma structure, the importance of which is 6-7%. Finally, tensile measurements performed on the different PVDF fibers clearly proves that their mechanical characteristics depend on the presence of these crystalline forms in the polymeric structure of PVDF.

Calorimetry, Differential Scanning↗
PubMed1998

Peptide surface modification of poly(tetrafluoroethylene-co-hexafluoropropylene) enhances its interaction with central nervous system neurons.

Poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) film surfaces were chemically surface modified to introduce one of three laminin adhesive peptides: GYIGSR, GRGDS, or SIKVAV. FEP film surfaces were first reduced with sodium naphthalide to introduce surface carbon-carbon double bonds at two reaction conditions: 20 min at -78 degrees C, and 3 h at 25 degrees C. Scanning electron microscopy and atomic force microscopy indicated that surface topography was unaffected by the reaction conditions. Reduced FEP film surfaces were further modified to introduce hydroxyl groups via hydroboration/oxidation or carboxylic acid groups via oxidation. The hydroxyl (FEP-CHxOH) and carboxylic acid (FEP-COOH) functionalized surfaces provided reactive handles for peptide coupling using tresyl chloride. Surface elemental composition data, determined from X-ray protoelectron spectroscopy, indicated that equivalent amounts of GYIGSR, GRGDS, and SIKVAV were introduced. Two additional coupling reagents, SMCC and TSU, were compared to tresyl chloride for the coupling of radio-labeled tyrosine of GYIGSR. Between 8 and 150 fmol/cm2 of peptide was introduced to the hydroxyl and carboxylic acid functionalized surfaces, with the tresyl coupling reagent showing the greatest amount of peptide incorporated. The tresyl-coupled peptide-modified surfaces were compared in terms of the response of primary, embryonic hippocampal neurons plated from serum-free medium for 4 days. The number and length of neurites extending from the cell bodies were averaged over 50 cells after 1 and 4 days FEP-CHxO-peptide surfaces had either a greater or equivalent hippocampal neuron interaction than the corresponding FEP-COO-peptide surfaces. All peptide-functionalized surfaces had a greater hippocampal neuron interaction than the corresponding FEP-CHxOH, FEP-COOH, and FEP controls after 4 days underlying the importance of the peptides over hydrophilic or hydrophobic surfaces. After 4 days differences in neurite extension were evident among the peptide-functionalized surfaces, with the longest neurites observed on the SIKVAV-functionalized surfaces.

Animals↗