Synthesis of acryl- and methacryl-type macromonomers and telechelics by utilizing living polymerization of 2-oxazolines

Abstract

Acryl-and methacryl-type macromonomers and telechelics of poly(2-alkyl-2-oxazolines) (PROZO) have been prepared for the first time by terminating the living ends in the electrophilic (cationic) ring-opening polymerization of 2-alkyl-2-oxazolines (ROZO) with suitable reagents. The synthesis of macromonomers was achieved via the following two methods: (1) by the reaction of acryloyl or methacryloyl chloride with a PROZO alcohol obtained by the hydrolysis of the living PROZO propagating species under basic conditions (indirect method) and ( 2) by the termination of the living species with carboxylate anions of acrylic or methacrylic acids or with trimethylsilyl methacrylate (direct method). The production of telechelics of PROZO was achieved by using a bis(2-oxazolinium salt) initiator. Termination of both living ends of the PROZO with water, ammonia, or an alkylamine afforded the corresponding telechelics of PROZO as glycols and diamines in good yields.

Preparation of Methacrylate End-Functionalized Poly(2-ethyl-2-oxazoline) Macromonomers

“…Thus, the obtained living polymer chains can be terminated with water leading to the formation of a hydroxyl terminated oligo(EtOx) (OEtOxOH). As known from the literature [19], the alcohol is formed as the thermodynamically favoured product during a rearrangement of an ester structure, which is reported to be the kinetically favoured product. Using this synthetic procedure well-defined hydroxyl-functionalized EtOx oligomers were synthesized with varying degrees of polymerization (for GPC traces see Fig.…”

“…On the one hand, it might be possible to use a functionalized initiator [16,17], while, on the other hand, the living cationic chain end can be terminated by nucleophiles, containing a methacrylate or another functional group that can be transformed into a methacrylate [18][19][20][21].…”

“…It is known that a hydroxyl-terminated PEtOx can be obtained by end-capping the living polymer chain with an aqueous solution of potassium hydroxide or sodium carbonate [19]. Subsequently, functionalization of the alcohol with methacryloyl chloride leads to the methacrylate macromonomers [19,21] (see Scheme 2).…”

“…Such a desired anion can easily be formed by the deprotonation of methacrylic acid with a suitable base, either triethyl amine [19] or the more sterically hindered lutidine [20]. This method has already been used to obtain methacrylate functionalized MeOx oligomers [20], as well as acrylate-functionalized EtOx oligomers [19].…”

Polymers for Protein Conjugation

“…PEOZ is soluble in water and in many organic solvents [92]. Like PEG, PEOZ can be synthesized with low polydispersity and can have a single functional group at one extreme, useful for protein conjugation, which is obtained during the initiation [93][94][95] or termination [96,97] steps of polymerization. The pharmacokinetics of PEOZ is directly proportional to its M W and, consequently, to its hydrodynamic volume, which is slightly lower than that of a PEG having the same M W [98].…”