A well-defined block copolymer synthesis via living cationic polymerization and nitroxide-mediated polymerization using carboxylic acid-based alkoxyamines as a dual initiator

121

With the advancement of polymer engineering, complex star-shaped polymer architectures can be synthesized with ease, bringing about a host of unique properties and applications. The polymer arms can be functionalized with different chemical groups to fine-tune the response behavior or be endowed with targeting ligands or stimuli responsive moieties to control its physicochemical behavior and self-organization in solution. Rheological properties of these solutions can be modulated, which also facilitates the control of the diffusion of the drug from these star-based nanocarriers. However, these star-shaped polymers designed for drug delivery are still in a very early stage of development. Due to the sheer diversity of macromolecules that can take on the star architectures and the various combinations of functional groups that can be cross-linked together, there remain many structure-property relationships which have yet to be fully established. This review aims to provide an introductory perspective on the basic synthetic methods of star-shaped polymers, the properties which can be controlled by the unique architecture, and also recent advances in drug delivery applications related to these star candidates.

Section: Polymerization Techniquesmentioning

confidence: 99%

Nano‐Star‐Shaped Polymers for Drug Delivery Applications

Yang

Deen

et al. 2017

121

“…As polymer synthesis techniques advance to enable more complex and controlled macromolecular architecture, so too must the analytical techniques used to probe such architecture. Tandem mass spectrometry has been utilized in tackling this challenge, showing success in probing microstructure, end‐group determination, backbone modifications, branching, and other macromolecular structures . The field of “polymeromics” is expanding; however, this is not as well developed as neighboring fields such as proteomics and petroleomics.…”

mentioning

confidence: 99%

Tandem Mass Spectrometry for Polymeric Structure Analysis: A Comparison of Two Common MALDI–ToF/ToF Techniques

Town

Jones

Hancox

et al. 2019

Tandem mass spectrometry is a powerful technique for investigating polymer architecture. However, in‐depth studies of the technique for polymers is relatively lacking when compared to other areas of mass spectrometry (MS). This paper examines the use laser‐induced dissociation and collision‐induced dissociation (CID) in MALDI–LIFT–ToF/ToF experiments to compare the usage of the two techniques on a range of polymeric analytes. It is demonstrated that for samples with an energetically preferable fragmentation pathway, such as those with a functional group in the backbone or a labile end group, post source decay (PSD) provides a simplified spectra with an increased pathway selectivity due to its utilization of metastable decay. This makes PSD a preferable technique for polymer sequencing, especially in low‐resolution time‐of‐flight techniques. Conversely, CID fragments less selectively, leading to higher intensity peaks from less favorable fragmentations. This makes CID more preferred for exact structural determination, such as finding the repeat unit structure.

“…Reported combinations concern mainly cationic polymerizations of cyclic ethers . Adaption of living cationic polymerization of vinyl ethers catalyzed by Lewis acids to photochemical process increased its use in mechanistic transformation approach . Photochemical processes in general exhibit an advantage of being applicable at low temperatures and producing reactive sites at defined positions in the macromolecule by the suitably selected chromophore groups that is a vital issue in the mechanistic transformation approach .…”

Section: Methodsmentioning

confidence: 99%

Block Copolymers by Mechanistic Transformation from PROAD to Iniferter Process

Çiftçi

Yaǧcı

2018

A facile strategy for synthesizing block copolymers by the combination of two different living polymerization techniques, namely, photoinduced radical oxidation/addition/deactivation (PROAD) and iniferter processes is described. In the first step, PROAD polymerization of isobutyl vinyl ether using bromotriphenylmethane, dimanganese decacarbonyl (Mn (CO) ), and diphenyliodonium bromide (Ph I Br ) is carried out to yield polymers with triphenylmethyl (trityl) end groups. These prepolymers are used as macroiniferters in thermally induced free radical polymerization of vinyl monomers such as methyl methacrylate, tert-butyl acrylate, and styrene, resulting in the formation of corresponding block copolymers free from homopolymers. The precursor polymer and final block copolymers are characterized by H NMR, FT-IR, GPC, and DSC analyses.