Facile Synthesis and Thermoresponsive Behaviors of a Well-Defined Pyrrolidone Based Hydrophilic Polymer

Abstract

A well-defined pyrrolidone based thermoresponsive polymer, poly [N-(2-methacryloyloxyethyl) pyrrolidone] (PNMP), was synthesized via reversible addition-fragmentation chain transfer radical polymerization or RAFT polymerization of N-(2-methacryloyloxyethyl) pyrrolidone monomer in methanol under a mild Visible light radiation at 30 °C. The average molecular weights and polydispersity indices of PNMP polymers were characterized by gel permeation chromatography (GPC) and static light scattering analysis. The kinetic studies indicated that this RAFT polymerization exhibited a well-controlled behavior. The living character of this RAFT polymerization was confirmed by the facile synthesis of a series of well-defined PNMP-based block copolymers via RAFT polymerization under this mild visible light radiation at 30 °C using the above-synthesized PNMP polymer as a macromolecular chain transfer agent. Temperature-variation 1 H NMR unambiguously revealed that the PNMP polymer with weight-average molecular weight (M w ) of 105.4 kg mol -1 and polydispersity index (M w /M n ) of 1.11 was molecularly dissolved in D 2 O at ambient temperature, e.g. 22 °C. Upon elevating the solution temperature, the dehydration process of this fully hydrated PNMP polymer was triggered at 46.1 °C, leading to a dramatic decrease of integral ratios of proton resonance signals of PNMP to that of D 2 O. Further elevating the solution temperature to 51.9 °C led to a sharp phase separation of PNMP polymer from aqueous solution. Laser light scattering analyses demonstrated that the cloud point of the PNMP polymer decreased with molecular weight in the M w range of 20.6-105.4 kg mol -1 . Moreover, this PNMP polymer exhibited a remarkably reversible thermoresponsive dehydration/hydration and phase transition behaviors in aqueous solution. Unlike what was observed in PNIPAM aqueous solution, no hysteresis phenomenon was observed in PNMP aqueous solution during one heating-and-cooling cycle.

Facile synthesis of well‐defined pH‐liable Schiff‐base‐type photosensitive polymers via visible‐light‐activated ambient temperature RAFT polymerization

“…Increasing [PAAEMA] 0 :[CPFDB] 0 :[TPO] 0 from 50:1:0.3 to 100:1:0.3, and finally to 150:1:0.3 leads to the decrease of slope, indicating that higher [PAAEMA] 0 :[CPFDB] 0 :[TPO] 0 leads to slower polymerization rate. This tendency is contrary to what observed in RAFT polymerization of GMA monomer47 or pyrrolidone‐derived methacrylic monomer55 under the same polymerizing conditions. Clearly, more experiments are necessary to clarify this phenomenon, but beyond the scope of this article.…”

Thermoresponsive Synergistic Hydrogen Bonding Switched by Several Guest Units in a Water‐Soluble Polymer

“…In contrast, as shown in the bottom figure of Figure 3b, this hysteresis could not be detected on heating and then cooling the solution of PNMEP 57 ‐ b ‐P(NMEP 7 ‐ stat ‐FPHPMA 6 ) or PNMEP 63 ‐ b ‐PFPHPMA 7 . As previously observed by Lutz et al,13 Li and coworkers,14 Wu and coworkers15 and our group,16 the hysteresis was negligible on heating‐cooling the aqueous solutions of random copolymers based on oligo(ethylene glycol) methacrylate and 2‐(2‐methoxyethoxy)ethyl methacrylate, oligo(ethylene glycol) acrylate and 2‐(5,5‐dimethyl‐1,3‐dioxan‐2‐yloxy)ethyl acrylate, and the homopolymers of pyrrolidone‐based (meth)acrylates, whose phase transitions were mainly induced by the hydrophobic association of apolar or less polar polymer backbones and unit spacers. Accordingly, it may be concluded that the H‐bonding that had been already consumed during preorganization (see Figure 2) did not contribute to this thermo‐triggered phase transition.…”

Water-based synthesis of cationic hydrogel particles: effect of the reaction parameters and in vitro cytotoxicity study

“…The size distribution of the resulting hGPs was characterized by dynamic light scattering (DLS) and the result is shown in Fig. [27][28][29][30][31][32] As step-two reaction took Intuitively, one would expect the particles to grow in size as the reaction time prolongs.…”