Synthesis and properties of gradient copolymers based on 2‐phenyl‐2‐oxazoline and 2‐nonyl‐2‐oxazoline

Abstract

In this study, the structure–property relationships for a series of statistical 2‐nonyl‐2‐oxazoline (NonOx) and 2‐phenyl‐2‐oxazoline (PhOx) copolymers were investigated for the first time. The copolymerization kinetics were studied and the reactivity ratios were calculated to be rNonOx = 7.1 ± 1.4 and rPhOx = 0.02 ± 0.1 revealing the formation of gradient copolymers. The synthesis of a systematical series of NonOx–PhOx copolymers is described, whereby the amount of NonOx was increased in steps of 10 mol %. The thermal and surface properties were investigated for this series of well‐defined copolymers. The thermal properties revealed a linear decrease in glass transition temperature for copolymers containing up to 39 wt % NonOx. Furthermore, the melting temperature of the copolymers containing 0 to 55 wt % PhOx linearly decreased most likely due to disturbance of the NonOx crystalline domains by incorporation of PhOx in the NonOx part of the copolymer. The surface energies of spincoated polymer films revealed a strong decrease in surface energy upon incorporation of NonOx in the copolymers due to strong phase separation between NonOx and PhOx allowing the NonOx chains to orient to the surface. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6433–6440, 2009

Solution Behavior of Hydrolyzed Gradient Methyl/Phenyl Oxazoline Copolymers and Complexation with DNA

“…[ 18,20 ] The degree of hydrolysis was found to be lower than those reported in refs. [ 18 ] and [ 21 ] . This should be attributed to the fact that in our case hydrolysis did not occur under microwave irradiation but via conventional heating.…”

“…It seems that the degrees of hydrolysis are nearest to the study of ref. [ 18 ] in which after a hydrolysis time of 2 and 5 h a major part of PhOx side groups were still present and only part of the MeOx groups were cleaved.…”

“…LPEI block polymers (from hydrolysis of PMeOx-b-PPOx, PMeOx-stat-PPhOx, PMeOx-b-PPhOx, and PMeOx-b-PEtOx) were found to be pH responsive, forming micelles in acidic solutions. [18][19][20] The maximum selectivity was achieved for acidic hydrolysis (with MeOx side groups being easier to remove) under microwave irradiation when 80:20 ethanol-water solvent mixture was used. [ 20 ] There is small amount of literature, however, concerning the gradient PEI copolymers and their interaction with DNA, and even less about PEI containing polymers in phosphate buffer saline (PBS) solutions or other biologically relevant media.…”

Poly(2‐oxazoline)s based on fatty acids

“…In addition, Hoogenboom and Schubert investigated the copolymerization of NonOx with PhOx, which is a less nucleophilic monomer [44]. As a result, gradient copolymers with a strong gradient from NonOx-rich to pure PhOx along the polymer chain are obtained that can be regarded as quasidiblock copolymers.…”

Design Strategies for Functionalized Poly(2-oxazoline)s and Derived Materials

“…Schubert et al synthesized a series of gradient p n NonOx-stat-pPhOx copolymers (due to the pronouncedly different reactivity ratios of n NonOx and PhOx) [161]. Regarding the pronouncedly different polymerization rates of alkyl-substituted 2-oxazolines and their aromatic counterparts, Schubert and co-workers studied the kinetics and reactivity ratios of statistical microwave-assisted copolymerizations of PhOx with either MeOx or EtOx [162].…”