Functional polymers based on high hydrophilicity of poly(2-methyl-2-oxazoline)

Polymers of the family of 2-substituted 2-oxazolines have the general structure of poly(N-acylethylenimine), whose hydrophilic/lipophilic properties vary according to the substituent, i.e., the acyl group of the polymer. Of special interest is the polymer of 2-methyl-substituted monomer, which has a strong affinity for water. Another useful feature of the 2-oxazoline family is the fact that its polymerization reaction is quite clean without disturbance by chain transfer and termination. On the basis of the above characteristics, three kinds of novel materials of functional polymers have been explored:

• 1. Non-ionic polymeric surfactants.
• 2. Non-ionic hydrogels.
• 3. Block copolymer with silica gel: Organic/inorganic polymers hybrids.

     

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.