화학공학소재연구정보센터
Macromolecules, Vol.48, No.24, 8947-8957, 2015
Arrangement of Conductive Rod Nanobrushes via Conductive-Dielectric-Conductive Sandwiched Single Crystals of Poly(ethylene glycol) and Polyaniline Block Copolymers
Conductive rod nanobrushes of polyaniline (PANI) were developed via the growth of conductive-dielectric-conductive sandwiched single crystals obtained from poly(ethylene glycol) (PEG(5000))-b-PANI(n) PANI(n)-b-PEG(6000)-b-PANT(n), and PANI(n)-b-PEG(35000)b-PANI, block copolymers synthesized by interfacial polymerization fostering two different oxidants (ammonium peroxydisulfate (APS) as a weaker and potassium hydrogen biiodate (PHD) as a stronger oxidant). Based on the dispersity of the diameter of the PANT nanofibers and the various molecular weights of PEG substrates, two distinct morphologies were detected, i.e., matrix dispersed morphology for PANIn-b-PEG(35000)b-PANI and dispersed dispersed morphology for PANI -b-PEG(6000)-bPANI(n) and PEG(5000)-b-PANI(n) single crystals. In matrix dispersed single crystals, through an elevated crystallization temperature (TA a convergence occurred between the heights of matrix (partly stretched PANIs) and disperses (fully stretched PANIs). Because of their higher conductivity (e.g., 3 vs 10(-4) S/cm for copolymers and 84 vs 8 x 10(-3) S/cm for corresponding homopolymers), the variation in height between the matrix and disperses was lower in PHD-synthesized PANT nanofibers (e.g., height variance of 2 rim for PHD-synthesized PANT,80 vs 57 nm for APS-synthesized PANI(175) at T-c = 38 degrees C). The diameter of the dispersed PANT was inversely proportional to the crystallization temperature and was directly proportional to the PANI repeating units. Although in PEG(35000)-based systems PANT-dispersed diameters of up to 58 nm were detected in PANI(109)-b-PEG(795)-b-PANI(109) single crystals at Tc = 18 degrees C due to a scarcity in the provided surface area, the maximum diameters included in PEG(6000) and PEG(5000) single crystals were 9 and 7 nm, respectively. In dispersed dispersed morphologies, having extended conformation of PANT brushes on PEG(5000) and PEG(6000) substrates, their substrate thickness did not vary by the lengthening of the PANT brushes, and the only effect oxidant had in these systems was on the population of grown single crystals; that is, the weaker the oxidant, the larger the population.