Dynamics of the Phase Separation in a Thermoresponsive Polymer: Accelerated Phase Separation of Stereocontrolled Poly( N, N-diethylacrylamide) in Water

Thermoresponsive Poly(N,N-diethylacrylamide-co-glycidyl methacrylate) Copolymers and Its Catalytically Active α-Chymotrypsin Bioconjugate with Enhanced Enzyme Stability

Responsive (smart, intelligent, adaptive) polymers have been widely explored for a variety of advanced applications in recent years. The thermoresponsive poly(N,N-diethylacrylamide) (PDEAAm), which has a better biocompatibility than the widely investigated poly(N,N-isopropylacrylamide), has gained increased interest in recent years. In this paper, the successful synthesis, characterization, and bioconjugation of a novel thermoresponsive copolymer, poly(N,N-diethylacrylamide-co-glycidyl methacrylate) (P(DEAAm-co-GMA)), obtained by free radical copolymerization with various comonomer contents and monomer/initiator ratios are reported. It was found that all the investigated copolymers possess LCST-type thermoresponsive behavior with small extent of hysteresis, and the critical solution temperatures (CST), i.e., the cloud and clearing points, decrease linearly with increasing GMA content of these copolymers. The P(DEAAm-co-GMA) copolymer with pendant epoxy groups was found to conjugate efficiently with α-chymotrypsin in a direct, one-step reaction, leading to enzyme-polymer nanoparticle (EPNP) with average size of 56.9 nm. This EPNP also shows reversible thermoresponsive behavior with somewhat higher critical solution temperature than that of the unreacted P(DEAAm-co-GMA). Although the catalytic activity of the enzyme-polymer nanoconjugate is lower than that of the native enzyme, the results of the enzyme activity investigations prove that the pH and thermal stability of the enzyme is significantly enhanced by conjugation the with P(DEAAm-co-GMA) copolymer.

Formation of Single Double-Layered Coacervate of Poly(N,N-diethylacrylamide) in Water by a Laser Tweezer

We demonstrate liquid-liquid phase separation involving both coacervation and coil-to-globule phase transition of a thermoresponsive polymer. By focusing a near-infrared laser beam into an aqueous solution of poly(N-isopropylacrylamide) (PNIPAM), a single phase-separated polymer microdroplet can be formed and stably trapped at the focal point. Such droplet formation is induced by a local elevation in temperature (induced by a photothermal effect) and an optical force. The technique allows us to selectively analyze a single polymer droplet trapped at the focal point. In this study, we applied this technique to poly(N,N-diethylacrylamide) (PDEA) in water and generated a double-layered PDEA droplet. Such an inhomogeneous and complex microstructure has not been previously observed both in steady-state heating of a PDEA solution and in the PNIPAM system. Moreover, we used micro-Raman spectroscopy to clarify that PDEA underwent dehydration due to a coil-to-globule phase transition. Despite this, the polymer concentration (C_poly) of the trapped PDEA droplet was very low and was around 30 wt %. C_poly depended on the molecular weight of PDEA and the laser power that regulates the temperature elevation. These results strongly indicate that PDEA undergoes coacervation in addition to a coil-to-globule phase transition. This study will help provide us with a fundamental understanding of the phase separation mechanisms of thermoresponsive polymers.

Application of the liquid-liquid dispersed microextraction based on phase transition behavior of temperature sensitive polymer to rapidly detect 5 BPs in food packaging

In this paper, temperature sensitive polymer p(MAH-β-CD-co-NIPAM) was used as extraction in DLLME, because its phase transition behavior can be observed at room temperature due to Hofmeister and non-co-solvent effect. The whole pretreatment process is simple and fast, and the extraction process did not require dispersant to assist dispersion and centrifugation to collect the adsorbent. A new analytical method based on DLLME coupled with HPLC-UV was developed to detect five types of BPs in milk and take-out packaging. The limits of detection ranged from 0.44 to 1.60 ng mL^-1 (S/N = 3). The relative recoveries of 5 BPs in food packaging were in the range of 91.08-108.04%.

Multiple stimuli-switchable electrocatalysis and logic gates of rutin based on semi-interpenetrating polymer network hydrogel films

The switching properties of PAA–PDEA films polymerized as a semi-IPN were studied with rutin as a probe and a logic gate was constructed.

Design of smart polyacrylates showing thermo-, pH-, and CO2-responsive features

A novel acrylate monomer was synthesized by facile sequential two-step reactions and polymerized using RAFT polymerization to yield a well-defined thermo-, pH- and CO₂-responsive homopolymer.