Synthesis and Thermoresponsive Solution Properties of Poly[oligo(ethylene glycol) (meth)acrylamide]s: Biocompatible PEG Analogues

RAFT polymerization to form stimuli-responsive polymers

Stimuli-responsive polymers respond to a variety of external stimuli, which include optical, electrical, thermal, mechanical, redox, pH, chemical, environmental and biological signals. This paper is concerned with the process of forming such polymers by RAFT polymerization.

Thermoresponsive Polymers and Inverse Opal Hydrogels for the Detection of Diols

Responsive inverse opal hydrogels functionalized by boroxole moieties were synthesized and explored as sensor platforms for various low molar mass as well as polymeric diols and polyols, including saccharides, glycopolymers and catechols, by exploiting the diol induced modulation of their structural color. The underlying thermoresponsive water-soluble copolymers and hydrogels exhibit a coil-to-globule or volume phase transition, respectively, of the LCST-type. They were prepared from oligoethylene oxide methacrylate (macro)monomers and functionalized via copolymerization to bear benzoboroxole moieties. The resulting copolymers represent weak polyacids, which can bind specifically to diols within an appropriate pH window. Due to the resulting modulation of the overall hydrophilicity of the systems and the consequent shift of their phase transition temperature, the usefulness of such systems for indicating the presence of catechols, saccharides, and glycopolymers was studied, exploiting the diol/polyol induced shifts of the soluble polymers' cloud point, or the induced changes of the hydrogels' swelling. In particular, the increased acidity of benzoboroxoles compared to standard phenylboronic acids allowed performing the studies in PBS buffer (phosphate buffered saline) at the physiologically relevant pH of 7.4. The inverse opals constructed of these thermo- and analyte-responsive hydrogels enabled following the binding of specific diols by the induced shift of the optical stop band. Their highly porous structure enabled the facile and specific optical detection of not only low molar mass but also of high molar mass diol/polyol analytes such as glycopolymers. Accordingly, such thermoresponsive inverse opal systems functionalized with recognition units represent attractive and promising platforms for the facile sensing of even rather big analytes by simple optical means, or even by the bare eye.

Facile production of nanoaggregates with tuneable morphologies from thermoresponsive P(DEGMA-co-HPMA)

RAFT-mediated emulsion polymerization of styrene and subsequent morphological transition produces nanoaggregates with tuneable morphologies.

Soft amphiphilic polyesters obtained from PEGs and silicon fatty compounds: structural characterizations and self-assembly studies

Transesterification polymerizations between a silicon fatty ester derived from methyl 10-undecenoate and polyethylene glycol (PEG) monomers generate amphiphilic biopolyesters ​showing abilities to form micelle and fiber structures.

Preparation of upper critical solution temperature (UCST) responsive diblock copolymers bearing pendant ureido groups and their micelle formation behavior in water

Poly(2-ureidoethyl methacrylate) (PUEM) was prepared via reversible addition-fragmentation chain transfer (RAFT) controlled radical polymerization and a post-modification reaction. PUEM shows upper critical solution temperature (UCST) behavior in aqueous solution. Although PUEM can dissolve in water above the UCST, it cannot dissolve in water below the UCST. Diblock copolymers (MmUn) composed of a biocompatible hydrophilic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) block and a PUEM block with different compositions were prepared via RAFT radical polymerization and a post-modification reaction. "M" and "U" represent PMPC and PUEM blocks, respectively, and the subscripts represent the degree of polymerization of each block. M95U149 and M20U163 formed polymer micelles comprising a PUEM core and a PMPC shell below the critical aggregation temperature (Tc) in aqueous solution. Polymer micelles were formed from M20U163 below 32 °C, which can incorporate guest molecules into the core.

Thiol-reactive functional poly(meth)acrylates: multicomponent monomer synthesis, RAFT (co)polymerization and highly efficient thiol–para-fluoro postpolymerization modification

Novel Passerini-made pentafluorophenyl-functional (meth)acrylate monomers are (co)polymerized by RAFT and modified quantitatively with a variety of functional primary, secondary, and tertiary thiols.

RAFT-prepared α-difunctional poly(2-vinyl-4,4-dimethylazlactone)s and their derivatives: synthesis and effect of end-groups on aqueous inverse temperature solubility

Five R-group di-functional dithiobenzoates have been prepared and used in the reversible addition–fragmentation chain transfer polymerization of 2-vinyl-4,4-dimethylazlactone.

Doubly responsive polymersomes towards monosaccharides and temperature under physiologically relevant conditions

A new class of doubly-responsive block copolymers could be utilized as new delivery vehicles for cargo molecules such as insulin.

The synthesis and aqueous solution properties of sulfobutylbetaine (co)polymers: comparison of synthetic routes and tuneable upper critical solution temperatures

With an additional methyl group in the ion bridge, sulfobutylbetaine (co)polymers show significantly higher UCSTs than their more common sulfopropylbetaine counterparts making them a promising class of smart materials.

Multicomponent isocyanide-based synthesis of reactive styrenic and (meth)acrylic monomers and their RAFT (co)polymerization

A combination of the Passerini reaction and RAFT polymerization is used to produce novel (co)polymers carrying double bond, protected triple bond, protected alcohol, pentafluorophenyl, and diene side group functionality.

Post-polymerization modification of reactive polymers derived from vinylcyclopropane: a poly(vinylcyclopropane) derivative with physical gelation and UCST behaviour in ethanol–water mixtures

In this paper we describe a new polymer that combines an upper critical solution temperature (UCST) and reversible physical gelation in ethanol–water mixtures.

Thiol–ene “click” reactions and recent applications in polymer and materials synthesis: a first update

This contribution serves as an update to a previous review (Polym. Chem.2010,1, 17–36) and highlights recent applications of thiol–ene ‘click’ chemistry as an efficient tool for both polymer/materials synthesis as well as modification.

Doubly thermo-responsive ABC triblock copolymer nanoparticles prepared through dispersion RAFT polymerization

Doubly thermo-responsive triblock copolymer nanoparticles are prepared by a dispersion RAFT polymerization and the nanoparticles exhibit a two-step phase-transition with increasing temperature.

Zwitterionic moieties from the Huisgen reaction: a case study with amphiphilic dendritic assemblies

Supramolecular nano-assemblies that reduce nonspecific interactions with biological macromolecules, such as proteins, are of great importance for various biological applications. Recently, zwitterionic materials have been shown to reduce nonspecific interactions with biomolecules, owing both to their charge neutrality and their ability to form a strong hydration layer around zwitterions via electrostatic interactions. Here, new triazole-based zwitterionic moieties are presented that are incorporated as the hydrophilic functionalities in facially amphiphilic dendrons. The amphiphilic zwitterionic dendrons spontaneously self-assemble in aqueous solutions forming micelle-type aggregates, which were confirmed by DLS, TEM, and fluorescence techniques. The structural and functional characteristics of the zwitterionic dendrons are also compared with the corresponding charge-neutral PEG-based dendrons and anionic carboxylate-based dendrons. Surface-charge measurements, temperature sensitivity and evaluation of interactions of these assemblies with proteins form the bases for these comparisons.

Selective Postmodification of Copolymer Backbones Bearing Different Activated Esters with Disparate Reactivities

In this communication, we report an easy method for introducing functional groups into polymer structures by successively reacting two different activated ester functionalities (pentafluorophenyl (PFP) ester and azlactone (AZ)) with different functional amine compounds. By exploiting the difference in reactivity of the two activated esters (PFP and AZ) toward different amino compounds, we demonstrate, for the first time, a selective modification of the different activated ester groups, thereby introducing functional groups to the polymer backbone in a controlled manner. Statistical and block copolymers of vinyl dimethyl azlactone (VDM) and pentafluorophenyl acrylate (PFPA), i.e.,(p(VDM-stat-PFPA)) and (p(VDM-block-PFPA)), were prepared using reversible addition-fragmentation transfer (RAFT) polymerization and subsequently modified using a library of amino compounds, yielding macromolecules with bespoke functionality. In additional work, the functional macromolecules were self-assembled into nanoparticles.