Temperature responsive bio-compatible polymers based on poly(ethylene oxide) and poly(2-oxazoline)s

https://pubs.rsc.org/en/content/articlepdf/2017/py/c6py01320a

Thermoresponsive poly(2-oxazoline)s, polypeptoids, and polypeptides

Polyoxazolines (POx) are increasingly being studied as polymeric building blocks due to the possibility of affording tunable properties. Additionally, as the biocompatibility and stealth behavior of POx are similar to that of poly(ethylene glycol) (PEG), it has become challenging to develop polyoxazoline-based (co)polymers. Even if POx have a lot of advantages, they also show an important drawback, as it has been impossible, to date, to prepare high-molecular-weight polyoxazolines with a low polydispersity index. Thus, it appears important that they be judiciously functionalized. This review covers the multiple ways that polyoxazolines can be functionalized. The use of functional initiators, functional terminating agents, and 2-R-2-oxazolines with an R functional side group is detailed. In conclusion, some perspectives on POx functionalizations are also reported, with functions permitting selective "click" reactions.

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How to Modulate the Chemical Structure of Polyoxazolines by Appropriate Functionalization

Poly(2-oxazoline)s (PAOx) are of increasing importance for a wide range of applications, mostly in the biomedical field. This review describes the synthesis of 2-oxazoline monomers, their cationic ring-opening polymerization (CROP) and gives a comprehensive overview of all reported PAOx homopolymers. In the second part of the review, the polymer properties of these PAOx homopolymers with varying side-chain structures are discussed. Altogether, this review intends to serve as encyclopedia for poly(2-oxazoline)s enabling the straightforward selection of a polymer structure with the desired properties for a certain application.

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Poly(2-oxazoline)s: A comprehensive overview of polymer structures and their physical properties

The conjunction of polymers and medicine enables the development of new materials that display novel features, opening new ways to administrate drugs, design implants and biosensors, to deliver pharmaceuticals impacting cancer treatment, regenerative medicine or gene therapy. Poly(2-oxazoline)s (POx) constitute a polymer class with exceptional properties for their use in a plethora of different biomedical applications and are proposed as a versatile platform for the development of new medicine. Herein, a global vision of POx as a platform for novel biomaterials is offered, by highlighting the recent advances and breakthroughs in this fascinating field.

Poly(2-oxazoline)s as materials for biomedical applications

The synthesis and microwave-assisted living cationic ring-opening polymerization of 2-cyclopropyl-2-oxazoline is reported revealing the fastest polymerization for an aliphatic substituted 2-oxazoline to date, which is ascribed to the electron withdrawing effect of the cyclopropyl group. The poly(2-cyclopropyl-2-oxazoline) (pCPropOx) represents an alternative thermo-responsive poly(2-oxazoline) with a reversible critical temperature close to body temperature. The cloud point (CP) of the obtained pCPropOx in aqueous solution was evaluated in detail by turbidimetry, dynamic light scattering (DLS) and viscosity measurements. pCPropOx is amorphous with a significantly higher glass transition temperature (Tg ∼ 80 °C) compared to the amorphous poly(2-n-propyl-2-oxazoline) (pnPropOx) (Tg ∼ 40 °C), while poly(2-isopropyl-2-oxazoline) piPropOx is semicrystalline. In addition, a pCPropOx comb polymer was prepared by methacrylic acid end-capping of the living cationic species followed by RAFT polymerization of the ma...

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Anja Baumgärtel

Papers

Poly(2-cyclopropyl-2-oxazoline): From Rate Acceleration by Cyclopropyl to Thermoresponsive Properties