Synthesis of star‐shaped copolymers with methyl methacrylate and n‐butyl methacrylate by metal‐catalyzed living radical polymerization: Block and random copolymer arms and microgel cores

Various star‐shaped copolymers of methyl methacrylate (MMA) and n‐butyl methacrylate (nBMA) were synthesized in one pot with RuCl₂(PPh₃)₃‐catalyzed living radical polymerization and subsequent polymer linking reactions with divinyl compounds. Sequential living radical polymerization of nBMA and MMA in that order and vice versa, followed by linking reactions of the living block copolymers with appropriate divinyl compounds, afforded star block copolymers consisting of AB‐ or BA‐type block copolymer arms with controlled lengths and comonomer compositions in high yields (≥90%). The lengths and compositions of each unit varied with the amount of each monomer feed. Star copolymers with random copolymer arms were prepared by the living radical random copolymerization of MMA and nBMA followed by linking reactions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 633–641, 2002; DOI 10.1002/pola.10145     

A new ruthenium complex with an electron-donating aminoindenyl ligand for fast metal-mediated living radical polymerizations

A new ruthenium complex with an electron-donating aminoindenyl ligand induces a fast living radical polymerization of methyl methacrylate (MMA) in the presence of a chloride initiator to give polymers with controlled and variable molecular weights (Mn = 103-105) and very narrow molecular weight distributions (Mw/Mn < 1.1). The structure and high activity of the catalyst were analyzed by X-ray crystallography and cyclic voltammetry in comparison to those of a similar complex with an indenyl ligand.     

Elimination of dispersion effect in a white-light scanning interferometer by using a spectral analyzer

Optical Review - A general equation of the interference signal of white-light scanning interferometer (WSI) and its Fourier transform are derived. Based on these equations, a new method for...     

Asymmetric radical polymerization and copolymerization of N‐(1‐phenyldibenzosuberyl)methacrylamide and its derivative leading to optically active helical polymers

N‐(1‐Phenyldibenzosuberyl)methacrylamide (PDBSMAM) and its derivative N‐[(4‐butylphenyl)dibenzosuberyl]methacrylamide (BuPDBSMAM) were synthesized and polymerized in the presence of (+)‐ and (?)‐menthols at different temperatures. The tacticity of the polymers was estimated to be nearly 100% isotactic from the ¹H NMR spectra of polymethacrylamides derived in D₂SO₄. Poly(PDBSMAM) was not soluble in the common organic solvents, and its circular dichroism spectrum in the solid state was similar to that of the optically active poly(1‐phenyldibenzosuberyl methacrylate) (poly(PDBSMA)) with a prevailing one‐handed helicity, indicating that the poly(PDBSMAM) also has a similar helicity. Poly(BuPDBSMAM) was optically active and soluble in THF and chloroform. Its optical activity was much higher than that of the poly[N‐(triphenylmethayl)methacrylamide], suggesting that one‐handed helicity may be more efficiently induced on the poly(BuPDBSMAM). The copolymerization of BuPDBSMAM with a small amount of optically active N‐[(R)‐(+)‐1‐(1‐naphthyl)ethyl]methacrylamide, particularly in the presence of (?)‐menthol, produced a polymer with a high optical activity. The prevailing helicity may also be efficiently induced. The chiroptical properties of the obtained polymers were studied in detail. The chiral recognition by the polymers was also evaluated. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1304–1315, 2007     

Disturbance-free laser diode Sagnac interferometer using direct phase modulation

We exploited the wavelength tunability of the laser diode of a phase-shifting Sagnac interferometer to realize disturbance-free measurements. The Sagnac interferometer is robust against mechanical disturbances because it has a common path configuration and requires no special references. An unbalanced optical path was introduced between p- and s-polarized beams to enable easy phase shifting by direct current modulation. The experimental results indicate that the proposed system is effective for performing precise disturbance-free measurements.     

Stereogradient Polymers Formed by Controlled/Living Radical Polymerization of Bulky Methacrylate Monomers

Life RAFT : A bulky methacrylate monomer, triphenylmethyl methacrylate (TrMA), was polymerized with reversible addition–fragmentation chain transfer (RAFT) agents. Stereogradient polymers in which the isospecificity increased spontaneously as the monomer concentration decreased were formed by a polymerization–depolymerization equilibrium that can convert a less stable growing polymer terminal into a more stable form (see picture).

     

Cover Picture: Heterogeneously Hybridized Porous Coordination Polymer Crystals: Fabrication of Heterometallic Core–Shell Single Crystals with an In‐Plane Rotational Epitaxial Relationship (Angew. Chem. Int. Ed. 10/2009)

A porous copper coordination framework grew epitaxially as a single crystal on the surface of a single crystal of a porous zinc coordination framework, as described by S. Kitagawa and co‐workers in their Communication on page 1766 ff. The picture shows the structural relationship between the copper and zinc frameworks, which has been unveiled by synchrotron surface X‐ray diffraction measurements; in‐plane rotational epitaxial growth compensates for the different lattice constants of the two crystals.