Double Modification of Polymer End Groups through Thiolactone Chemistry

Applications of MALDI-TOF-MS in structural characterization of synthetic polymers

In recent years, matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has been utilized to rapidly and precisely characterize the detailed molecular structures of synthetic polymers. This review summarizes recent progress regarding MALDI-TOF-MS for the characterization of synthetic polymers with a focus on specific important experimental aspects including sample preparation, the choice of matrix, the effects of cationizing agents and solvents, data processing and various applications. Finally, the recent trend of MALDI-TOF-MS development is discussed. We hope this review will be instructive for graduate students and junior users who need to use MALDI-TOF-MS as a necessary characterization technique for new synthetic polymers.

Thiolactone chemistry, a versatile platform for macromolecular engineering

This review covers the extensive use of γ-thiolactone chemistry as a versatile and powerful tool for macromolecular engineering and the preparation of various polymer architectures, such as functional, alternating, or sequence-controlled (co)polymers.

Polythiolactone-Decorated Silica Particles: A Versatile Approach for Surface Functionalization, Catalysis and Encapsulation

The surface chemistry of colloidal silica has tremendous effects on its properties and applications. Commonly the design of silica particles is based on their de novo synthesis followed by surface functionalization leading to tailormade properties for a specific purpose. Here, the design of robust "precursor" polymer-decorated silica nano- and microparticles is demonstrated, which allows for easy post-modification by polymer embedded thiolactone chemistry. To obtain this organic-inorganic hybrid material, silica particles (SiO2 P) were functionalized via surface-initiated atom transfer radical polymerization (SI-ATRP) with poly(2-hydroxyethyl acrylate) (PHEA)-poly(thiolactone acrylamide (PThlAm) co-polymer brushes. Exploiting the versatility of thiolactone post-modification, a system was developed that could be used in three exemplary applications: 1) the straightforward molecular post-functionalization to tune the surface polarity, and therefore the dispersibility in various solvents; 2) the immobilization of metal nanoparticles into the polymer brushes via the in situ formation of free thiols that preserved catalytic activity in a model reaction; 3) the formation of redox-responsive, permeable polymer capsules by crosslinking the thiolactone moieties with cystamine dihydrochloride (CDH) followed by dissolution of the silica core.

Polyoxazolines with a Vicinally Double-Bioactivated Terminus for Biomacromolecular Affinity Assessment

Interactions between proteins and carbohydrates with larger biomacromolecules, e.g., lectins, are usually examined using self-assembled monolayers on target gold surfaces as a simplified model measuring setup. However, most of those measuring setups are either limited to a single substrate or do not allow for control over ligand distance and spacing. Here, we develop a synthetic strategy, consisting of a cascade of a thioesterification, native chemical ligation (NCL) and thiol-ene reaction, in order to create three-component polymer conjugates with a defined double bioactivation at the chain end. The target architecture is the vicinal attachment of two biomolecule residues to the α telechelic end point of a polymer and a thioether group at the ω chain end for fixating the conjugate to a gold sensor chip surface. As proof-of-principle studies for affinity measurements, we demonstrate the interaction between covalently bound mannose and ConA in surface acoustic wave (SAW) and surface plasmon resonance (SPR) experiments.

Synthesis of poly(amide-thioether) with tunable hydrophilicity via thiolactone chemistry and its application in oil-in-oil emulsions

Oil-in-oil emulsions are ideal systems for water-sensitive reactions such as polymerizations and catalytic reactions, which has received extensive attention in recent years. The application of oil-in-oil emulsions has been developed slowly due to the limited types of surfactants and complicated synthesis process. Herein, we proposed a simple method to prepare poly(amide-thioether)-based surfactant for oil-in-oil emulsions via taking advantage of single-pot multicomponent and click characters of thiolactone chemistry. Using a combination of alkyl amine and acrylamide thiolactone, the aminolysis of thiolctone occurred first, generating thiol group in-situ, and then the generated thiol group would sequentially react with the double bonds of acrylamide to form polythioether in the presence of amine. The hydrophobicity of the surfactant could be effectively adjusted by the chain length of the alkyl amine and thus this polymer could serve as a promising surfactant for oil-in-oil emulsion. Notably, the emulsion types could be switched by changing the chain length of the alkyl amine. In addition, the effects of surfactant loading, volume ratio of oil phases, oil types on the size and stability of oil-in-oil emulsions were further investigated. It was demonstrated that the oil-in-oil emulsion stabilized by poly(amide-thioether)s kept stable after more than five months. Besides, we preliminarily explored the application of the oil-in-oil emulsion to prepare closed cell foam and porous particles via photo-initiated thiol-ene polymerization. It is believed that this super-stable oil-in-oil emulsion could offer more possibilities for highly potential water-sensitive systems.

Mild and efficient synthesis of ω,ω-heterodifunctionalized polymers and polymer bioconjugates

Semi-telechelic ω,ω-heterodifunctional polymers and polymer bioconjugates are synthesized under mild conditions using benzotrifuranone.