Keh-Ying Hsu

Poly(lactide)-functionalized and Fe3O4 nanoparticle-decorated multiwalled carbon nanotubes for preparation of electrically-conductive and magnetic poly(lactide) films and electrospun nanofibers

Polymer-functionalized magnetic multiwalled carbon nanotubes (MWCNTs) have been prepared by a 2-step process. Fe3O4 nanoparticles are first decorated onto MWCNTs through Diels–Alder reaction. The resulting magnetic MWCNTs have been functionalized with polymers through an ozone-mediated process, which is able to incorporate kinds of matrix polymers to the magnetic MWCNTs. Poly(lactide)-functionalized magnetic MWCNTs (mCNT–PLA) have been prepared in this work for preparation of electrically-conductive and magnetic poly(lactide)/MWCNTs composite films and electrospun fibers. The magnetic and electrically-conductive feature of the functionalized MWCNTs helps to the formation of nanofibers in the electrospinning process of poly(lactide). The nanofibers possessing 0.3 wt% of mCNT–PLA exhibit a Youngs modulus and an elongation at break of 25 MPa and 150%, respectively. Compared to the values of 9 MPa and 12% shown with the neat PLA electrospun fibers, the presence of mCNT–PLA not only strengthens but also toughens the PLA-based electrospun fibers.

Studies on thermotropic liquid crystalline polymers: 4. Synthesis and properties of poly(ether ester amide)s

Abstract The thermotropic liquid crystalline behaviour of a series of aliphatic-aromatic poly(ether ester amide)s, which were prepared by direct polycondensation, was observed. Poly(ether ester amide)s I were prepared from 4,4′-diacrylic acid-α,ω-diphenoxyalkanes and 4-aminophenol or 4-amino-3-methylphenol in the presence of diphenylchlorophosphate (DPCP) and pyridine. Poly(ether ester amide)s II were prepared from 4,4′-dicarboxy-α,ω-diphenoxyalkanes and 4-aminophenol or 4-amino-3-methylphenol in the presence of DPCP and pyridine. The phase behaviour of the polymers was studied by differential scanning calorimetry and optical polarizing microscopy equipped with a heating stage. Poly(ether ester amide)s I exhibit thermotropic liquid crystalline characteristics, except in cases where methoxy or ethoxy groups were introduced into the benzene ring. All of the poly(ether ester amide)s II exhibit thermotropic liquid crystalline behaviour as observed by optical polarizing microscopy.

Photoluminescent toroids formed by temperature-driven self-assembly of rhodamine B end-capped poly(N-isopropylacrylamide).

In this paper, self-assembled polymeric toroids formed by a temperature-driven process are reported. Rhodamine B (RhB) end-capped poly(N-isopropylacrylamide) (PNIPAAm) demonstrating a lower critical solution temperature (LCST) is prepared. In a two-phase system, the polymer in the aqueous phase could move to the chloroform phase on raising the temperature above its LCST. This temperature-driven process results in the formation of polymeric toroids in the chloroform phase, and the strategy affords a new pathway to toroidal self-assembly of polymers. Moreover, the photoluminescent behavior of the RhB end-capped PNIPAAm species formed by the process is also studied and discussed.

Studies on thermotropic liquid crystalline polymers—V. Synthesis and properties of poly(ether amide)s

Abstract Two series of poly(ether amide)s, I and II, were prepared by direct polycondensation from 4,4′-diacrylic acid-α, ω-diphenoxyalkanes and 4,4′-dicarboxyl-α, ω-diphenoxyalkanes with diamines. The phase behaviour of these polymers was studied by differential scanning calorimetry and optical polarizing microscopy using a heated stage. Poly(ether amide) IId showed thermotropic liquid crystalline behaviour by observation under the optical polarizing microscope but poly(ether amide)s I and II did not exhibit thermotropic liquid crystallinity unambiguously. It is suggested that these results are due to interchain hydrogen bonds.