Synthesis and langmuir‐blodgett (LB) film properties of functional α,ω‐diamine amphiphilic materials

We have investigated the synthesis and ultrathin film forming properties of α,ω‐diamine derivatives. The amphiphiles were synthesized as precursors to the formation of ionene polymers. Two materials were investigated: oligothiophene and azobenzene functional groups. These type of materials are of great interest for the preparation of ultrathin film layers with applications for photochemical regulation of liquid crystal (LC) orientation, optical storage media, and electroluminescent displays. Azobenzene and its derivatives are well known photochemical systems exhibiting the reversible cis‐trans photoisomerization. Conjugated oligothiophene derivatives, exhibit interesting optical and electronic properties for applications such as light emitting diodes (LED)s, Schottky diodes, and thin film field‐effect transistors (TFT). The two amphiphiles behaved very differently as Langmuir monolayers and LB films. Dye aggregation was observed with the azobenzene derivatives compared with the oligothiophenes.     

Study on controlling particle growth in seeded emulsion polymerization with regulated coagulation based on the electrostatic interactions

30wt% solid content, anionic seed copolymer latex P(methyl acrylate-co-methyl methacrylate) was prepared by conventional emulsion polymerization, and then the seeded emulsion polymerization was carried out accompanied with the electrostatic coagulation during the reaction in the presence of counter-ion species, such as cationic monomer and initiator. In this article, effects of cationic monomer (dimethyl aminoethyl methacrylate, DM) content, secondary monomer to seed polymer weight ratio, M/P and amount of emulsifier (polyoxyethylene nonylphenylether with 23 units of ethylene oxide, PEO23) were investigated on the effective particle growth and the stability of final latex. With 10wt% DM in monomer, M/P ratio at 2.0 were recommended. An optimal policy for handling the emulsifier content without the nucleation of secondary particles while achieving the controlled coagulative growth was proposed from the observations of polymer yield and particle size during the polymerization.     

Polymerization chemistry of the family of cyclic imino ethers

Characteristics of the polymerization mechanisms of the family of cyclic imino ethers are described. The variety of the mechanism of propagation has been systematized on the basis of the nature of propagating species, i.e., cationic or electrophilic covalent (dipole) species. In the polymerizations of 2-alkyl cyclic imino ethers (5- and 6-membered), propagation mechanism via one of these two different species has been established, which is dependent upon the relative nucleophilic reactivities of the monomer and the counter anion derived from initiator. The polymerization of cyclic pseudoureas having a cyclic amine substituent at 2-position proceeds in two different ways. Ionic propagation leads to the single isomerization/ring-opening polymerization involving only the cyclic imino ether ring. On the other hand, covalent propagation gives rise to the double isomerization ring-opening polymerization involving the two rings of cyclic imino ether and cyclic amine. Polymerization of 5-membered cyclic iminocarbonate with a sulfonate initiator proceeds through the isomerization/ring-opening of 2-oxazoline ring. The same monomer was isomerized to the corresponding cyclic urethane when it was treated with benzyl bromide.