Synthesis of novel boronic acid-decorated poly(2-oxazoline)s showing triple-stimuli responsive behavior

Boronic acid-functionalized (co)polymers have gained increasing attention in the field of responsive polymers and polymeric materials due to their unique characteristics and responsiveness towards both changes in pH and sugar concentrations. This makes these (co)polymers excellently suited for various applications including responsive membranes, drug delivery applications and sensor materials. Unfortunately, boronic acid-based polymer research is also notorious for its challenging monomer synthesis and polymerization and its overall difficult polymer purification and manipulation. In light of this, many research groups have focused their attention on the optimization of various polymerization techniques in order to expand the field of BA-research including previously unexplored monomers and polymerization techniques. In this paper, a new post-polymerization modification methodology was developed allowing for the synthesis of novel boronic acid-decorated poly(2-alkyl-2-oxazoline) (PAOx) copolymers, utilizing the recently published PAOx methyl ester reaction platform. The developed synthetic pathway provides a straightforward method for the introduction of pH- and glucose-responsiveness, adding this to the already wide variety of possible responsive PAOx-based systems. The synthesized BA-decorated PAOx are based on the thermoresponsive poly(2-n-propyl-2-oxazoline) (PnPropOx). This introduces a pH and glucose dependence on both cloud and clearance point temperatures of the copolymer in aqueous and pH-buffered conditions, yielding a triply-responsive (co)polymer that highlights the wide variety of obtainable properties using this pathway

Dye modification of nanofibrous silicon oxide membranes for colorimetric HCl and NH3 sensing

Colorimetric sensors for monitoring and visual reporting of acidic environments both in water and air are highly valuable in various fields, such as safety and technical textiles. Until now sol-gel-based colorimetric sensors are usually nonflexible bulk glass or thin-film sensors. Large-area, flexible sensors usable in strong acidic environments are not available. Therefore, in this study organically modified silicon oxide nanofibrous membranes are produced by combining electrospinning and sol-gel technology. Two pH-indicator dyes are immobilized in the nanofibrous membranes: methyl yellow via doping, methyl red via both doping, and covalent bonding. This resulted in sensor materials with a fast response time and high sensitivity for pH-change in water. The covalent bond between dye and the sol-gel network showed to be essential to obtain a reusable pH-sensor in aqueous environment. Also a high sensitivity is obtained for sensing of HCl and NH3 vapors, including a memory function allowing visual read-out up to 20 min after exposure. These fast and reversible, large-area flexible nanofibrous colorimetric sensors are highly interesting for use in multiple applications such as protective clothing and equipment. Moreover, the sensitivity to biogenic amines is demonstrated, offering potential for control and monitoring of food quality

Plasma dye coating as straightforward and widely applicable procedure for dye immobilization on polymeric materials

Here, we introduce a novel concept for the fabrication of colored materials with significantly reduced dye leaching through covalent immobilization of the desired dye using plasmagenerated surface radicals. This plasma dye coating (PDC) procedure immobilizes a preadsorbed layer of a dye functionalized with a radical sensitive group on the surface through radical addition caused by a short plasma treatment. The non-specific nature of the plasmagenerated surface radicals allows for a wide variety of dyes including azobenzenes and sulfonphthaleins, functionalized with radical sensitive groups to avoid significant dye degradation, to be combined with various materials including PP, PE, PA6, cellulose, and PTFE. The wide applicability, low consumption of dye, relatively short procedure time, and the possibility of continuous PDC using an atmospheric plasma reactor make this procedure economically interesting for various applications ranging from simple coloring of a material to the fabrication of chromic sensor fabrics as demonstrated by preparing a range of halochromic materials

Responsive Boronic Acid-Decorated (Co)polymers: From Glucose Sensors to Autonomous Drug Delivery

Boronic acid-containing (co)polymers have fascinated researchers for decades, garnering attention for their unique responsiveness toward 1,2- and 1,3-diols, including saccharides and nucleotides. The applications of materials that exert this property are manifold including sensing, but also self-regulated drug delivery systems through responsive membranes or micelles. In this review, some of the main applications of boronic acid containing (co)polymers are discussed focusing on the role of the boronic acid group in the response mechanism. We hope that this summary, which highlights the importance and potential of boronic acid-decorated polymeric materials, will inspire further research within this interesting field of responsive polymers and polymeric materials

Responsive Boronic Acid-Decorated (Co)polymers: From Glucose Sensors to Autonomous Drug Delivery

Boronic acid-containing (co)polymers have fascinated researchers for decades, garnering attention for their unique responsiveness toward 1,2- and 1,3-diols, including saccharides and nucleotides. The applications of materials that exert this property are manifold including sensing, but also self-regulated drug delivery systems through responsive membranes or micelles. In this review, some of the main applications of boronic acid containing (co)polymers are discussed focusing on the role of the boronic acid group in the response mechanism. We hope that this summary, which highlights the importance and potential of boronic acid-decorated polymeric materials, will inspire further research within this interesting field of responsive polymers and polymeric materials

Synthesis and polymerization of boronic acid containing monomers

Boronic acid decorated copolymers have gathered significant interest in recent years. These (co) polymers are well-known for their saccharide responsive properties commonly applied in polymeric glucose sensors, cell capture and enzymatic inhibition. Despite this wide variety of applications, boronic acid containing monomers and resulting (co) polymers are also known for their notoriously difficult synthesis and purification. This review provides a condensed overview of the different synthetic pathways that have been reported for both monomer and (co) polymer synthesis. The first part of this review will focus on the synthesis of different boronic acid containing monomers bearing various polymerizable groups including (meth) acrylates, (meth) acrylamides and styrenics. These monomers show a wide variety in synthetic complexity but also in the Lewis acidity of the boronic acid moiety, which is of vital importance for success of the desired application. The second part will then discuss the main approaches for the (co) polymerization of these monomers divided into three groups, namely polymerization of unprotected boronic acid monomers, polymerization of protected boronate ester monomers and finally boronic acid incorporation through post-polymerization modification reactions. This review will complement the already numerous application-focused papers and provide a comprehensive overview of the currently used synthetic methodologies as guideline for boronic acid-containing (co) polymer research