title: Thermo-responsive nanofiber mats fabricated by electrospinning of poly(N-isopropylacrylamide-co-stearyl acrylate).
abstract: Copolymers of N-isopropylacrylamide and stearyl acrylate (PNIPA-SAX) with various SA feed ratios (X = 1-10 mol%) were synthesized and electrospun into nanofiber mats. It was found that average diameter of nanofibers electrospun at concentration of 25% and voltage of 30 kV linearly increased from 165 nm (PNIPA) to 497 nm (PNIPA-SA10) with increasing the SA content. The PNIPA-SAX (X = 3-10 mol%) nanofiber mats were insoluble in water at 25 degrees C, in which inter-polymer and interfiber physical cross-links were formed through hydrophobic interaction of stearyl side-chains. With increasing the temperature from 25 to 40 degrees C the PNIPA-SA3 nanofiber mat exhibited significant volume contraction of 66%, while that of a single nanofiber estimated by AFM measurements was found to be 37%. The results allowed us to conclude that not only swelling-deswelling but also dissociation-association of the nanofibers via hydrophobic interactions were crucially important for the macroscopic volume changes of the nanofiber mats.
authors.affiliation: Laboratory of Organic Robotics, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-4-37 Takeda, Kofu 400-8511, Japan.
authors.forename: Hidenori
authors.initials: H
authors.lastname: Okuzaki
authors.forename: Keiko
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Fumiya
authors.initials: F
authors.lastname: Hishiki
authors.forename: Shi-Jian
authors.initials: SJ
authors.lastname: Su
authors.forename: Hu
authors.initials: H
authors.lastname: Yan
mesh_terms: D000178:Acrylamides / Q000138:chemical synthesis / Q000737:chemistry*; D055664:Electrochemical Techniques; D057927:Hydrophobic and Hydrophilic Interactions; D008855:Microscopy, Electron, Scanning; D057139:Nanofibers / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology; D010316:Particle Size; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D013696:Temperature
chemical_list: D000178:Acrylamides; C090629:N-isopropylacrylamide-acrylic acid copolymer; D011108:Polymers