Novel multifunctional initiators for polymerization of 2-oxazolines

Abstract

Polymerization of 2-oxazolines was carried out using bifunctional and tetrafunctional initiators. Allyl-type dihalides and xylylene dihalides were used as bifunctional initiators. The allyl-type dihalides employed are l,4-dibromo-2-butene and 3-iodo-2-(iodomethyl)-1-propene and the xylylene dihalides are pxylylene diiodide and p-, m•, and o-xylylene dibromides. The degree of polymerization (DP) of the resulting polymer was very close to the feed ratio of the monomer to initiator. From a kinetic study, it was found that the polymerization using these bifunctional initiators for 2-oxazoline is a "fast initiation-slow propagation system". Electrophilic reactivities of allylic dibromide and allyl bromide were also evaluated by MO calculation to confirm the polymerization system. Tetrakis (bromomethyl)ethylene, an allylic tetrahalide, was used as a tetrafunctional initiator. The DP value of the polymer agreed well with the feed ratio. From NMR and GPC analyses the polymer was of star-shaped structure.

Porphyrin-centered Water-soluble Star-shaped Polymers: Poly(N-acetylethylenimine) and Poly(ethylenimine) Arms

“…ZnCMPP was prepared by refluxing a mixture containing CMPP and Zn(CH 3 COO) 2 in chloroform/methanol for 1 h. We confirmed that CMPP without halogen exchange by NaI did not initiate the polymerization at 60°C in acetonitrile at all, even when the reaction time was increased to 48 h. In contrast, the polymerization of 2-methyl-2-oxazoline occurred when CMPP or ZnCMPP was used as initiator associated with NaI [8,9] (in situ exchange of Cl with I by adding NaI to the reaction mixture). As reported by Kobayashi et al [8], a higher feed ratio of oxazoline to multihalogene initiator not only increases the average molecular weight of the polymer but also promotes the star shape formation.…”

“…For polymers 1-3, however, the values of M n determined by GPC (DMF as eluent, polystyrene as standard, with RI detector) were lower than those evaluated by 1 H NMR, and M n (by GPC) for 3 is only 1.5 times that for 1 ( Table 1). This is often seen in the case of star-shaped polymers owing to the lowered hydrodynamic diameter [8,9,14]. In addition, polymers 1 and 2 showed relatively narrow polydispersity, the value being 1.3.…”

“…In polymer architecture the living polymerization of oxazolines [7] using alkyl halides as initiators is well established, in which the halogen moves from one propagating site to the next while the alkyl residue attaches itself to the initial monomer unit on the polymer. This polymerization has provided a simple method to synthesize star-shaped polymers from multihalogene initiators [8,9]. In this paper we report a controlled star-shaped porphyrin polyoxazoline and its derivatives using 5,10,15,20-tetra-(p-chloromethylphenyl)porphyrin (CMPP) and its zinc form ZnCMPP as initiators.…”

Kinetic Investigations on the Polymerization of 2‐Oxazolines Using Pluritriflate Initators

“…[18] Some reports on star homo-and block coPOx can be found. [19][20][21][22] However, only two reports investigated whether all functionalities of a multifunctional initiator are of equal reactivity. In these cases, a step-wise initiation by the plurifunctional initiators, halogen and tosylate, was observed.…”

Synthesis and Solution Properties of Double Hydrophilic Poly(ethylene oxide)-block-poly(2-ethyl-2-oxazoline) (PEO-b-PEtOx) Star Block Copolymers

“…The outer block, poly(2-ethyl-2-oxazoline) (PEtOx), is water-soluble and non-toxic, and the pseudo-peptide character of this material has been shown to induce similar "stealth" behavior, as observed for PEO [19,22,[37][38][39]. PEtOx can be synthesized with a wide range of functional groups, being present via cationic ring-opening polymerization (CROP) [40][41][42][43]. We used different lengths of the outer PEtOx blocks, and the obtained [PEO 28 -b-PEtOx x ] 8 materials were characterized via size exclusion chromatography (SEC), nuclear magnetic resonance spectroscopy (NMR) and Fourier-transform infrared spectroscopy (FT-IR).…”