Tribocharged polymers display macroscopically patterned positive and negative domains, verifying the fractal geometry of electrostatic mosaics previously detected by electric probe microscopy. Excess charge on contacting polyethylene (PE) and polytetrafluoroethylene (PTFE) follows the triboelectric series but with one caveat: net charge is the arithmetic sum of patterned positive and negative charges, as opposed to the usual assumption of uniform but opposite signal charging on each surface. Extraction with n-hexane preferentially removes positive charges from PTFE, while 1,1-difluoroethane and ethanol largely remove both positive and negative charges. Using suitable analytical techniques (electron energy-loss spectral imaging, infrared microspectrophotometry and carbonization/colorimetry) and theoretical calculations, the positive species were identified as hydrocarbocations and the negative species were identified as fluorocarbanions. A comprehensive model is presented for PTFE tribocharging with PE: mechanochemical chain homolytic rupture is followed by electron transfer from hydrocarbon free radicals to the more electronegative fluorocarbon radicals. Polymer ions self-assemble according to Flory-Huggins theory, thus forming the experimentally observed macroscopic patterns. These results show that tribocharging can only be understood by considering the complex chemical events triggered by mechanical action, coupled to well-established physicochemical concepts. Patterned polymers can be cut and mounted to make macroscopic electrets and multipoles.
Background Among the many consequences of loss of CFTR protein function, a significant reduction of the secretion of bicarbonate (HCO 3 −) in cystic fibrosis (CF) is a major pathogenic feature. Loss of HCO 3 − leads to abnormally low pH and impaired mucus clearance in airways and other exocrine organs, which suggests that NaHCO 3 inhalation may be a low-cost, easily accessible therapy for CF. Objective To evaluate the safety, tolerability, and effects of inhaled aerosols of NaHCO 3 solutions (4.2% and 8.4%). Methods An experimental, prospective, open-label, pilot, clinical study was conducted with 12 CF volunteer participants over 18 years of age with bronchiectasis and pulmonary functions classified as mildly to severely depressed. Sputum rheology, pH, and microbiology were examined as well as spirometry, exercise performance, quality-of-life assessments, dyspnea, blood count, and venous blood gas levels. Results Sputum pH increased immediately after inhalation of NaHCO 3 at each clinical visit and was inversely correlated with rheology when all parameters were evaluated: [G′ (elasticity of the mucus) = − 0.241; G″ (viscosity of the mucus) = − 0.287; G* (viscoelasticity of the mucus) = − 0.275]. G* and G′ were slightly correlated with peak flow, forced expiratory volume in 1 s (FEV 1), and quality of life; G″ was correlated with quality of life; sputum pH was correlated with oxygen consumption (VO 2) and vitality score in quality of life. No changes were observed in blood count, venous blood gas, respiratory rate, heart rate, peripheral oxygen saturation of hemoglobin (SpO 2), body temperature, or incidence of dyspnea. No adverse events associated with the study were observed. Conclusion Nebulized NaHCO 3 inhalation appears to be a safe and well tolerated potential therapeutic agent in the management of CF. Nebulized NaHCO 3 inhalation temporarily elevates airway liquid pH and reduces sputum viscosity and viscoelasticity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.