We report here a novel direct method for the syntheses of primary aminoalkyl methacrylamides that requires mild reagents and no protecting group chemistry. The reversible addition‐fragmentation chain transfer polymerization (RAFT) of the aminoalkyl methacrylamide revealed to be highly efficient with 4‐cyanopentanoic acid dithiobenzoate (CTP) as chain transfer agent and 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) as initiator. Cationic amino‐based homopolymers of reasonably narrow polydispersities (Mw/Mn < 1.30) and predetermined molecular weights were obtained without recourse to any protecting group chemistry. A range of block and random copolymers were also synthesized via the RAFT process. The homopolymers and copolymers were characterized by aqueous conventional and triple detection gel permeation chromatography systems. Furthermore, the primary amine‐based methacrylamide monomers and polymers revealed to be highly stable both with the primary amino group in the protonated and deprotonated form. We have also demonstrated that stabilized gold nanoparticles can be generated with the RAFT‐synthesized amine‐based polymers via a photochemical process. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4984–4996, 2008

No abstract

No abstract

Ferroelectric ceramics of strontium bismuth tantalate, SrBi 2 Ta 2 O 9 (SBT), have been synthesized in pure layer-structured perovskite phase by two new soft chemical techniques, namely, a sol-gel process and a coprecipitation method. The sol-gel process utilizes ethylene glycol as solvent while the coprecipitation technique makes use of a poly(ethylene glycol) 200 (PEG) and methanol mixture as solvent. The microstructure and properties of the ceramics have been studied and discussed. The sol-gel-derived ceramics sintered at 1200°C for 8 h show good dielectric and ferroelectric properties with a relative density of 96%, a dielectric constant ′ ) 227, a remnant polarization P r ) 7.6 µC/cm 2 at room temperature, and a maximum dielectric constant ′ max ) 950 at the Curie temperature T C ) 330°C. In comparison, the SBT ceramics prepared using the coprecipitation method and sintered under the same conditions show a platelike microstructure with preferential grain orientation along the [0010] direction, a relative density of 85%, an ′ of 235, a P r of 3.7 µC/cm 2 at room temperature, and an ′ max of 850 at T C ) 330°C. The sol-gel-derived ceramics show superior dielectric and ferroelectric properties than the ceramics prepared by the solid-state reactions ( ′ max ≈ 500 and P r ) 4.5 µC/cm 2 ), which can be attributed to a denser and more homogeneous microstructure with a better distribution of grain orientations, thus reducing the preferential grain orientation along the nonpolar c-axis.

No abstract