Investigation of Fluorescent Shape Memory Polyurethanes Grafted with Various Dyes

Abstract

Shape memory polyurethane (SMPU), grafted with a fluorescent dye (Rhodamine, Mehylene violet, or Fluorescein) through an allophanate linking, was tested for the fluorescence and the shape recovery effect. The main chain of SMPU was composed of 4,4'-methylenebis(phenylisocyanate) (MDI), poly(tetramethyleneglycol) (PTMG), and 1,4-butanediol (BD), and a fluorescent dye was connected through a second MDI linked to the carbamate moiety of the main chain. Three series of SMPU, differing according to their dye content, were prepared to compare their shape recovery and fluorescence properties. In tensile mechanical property, maximum stress increased up to 350% compared to the linear SMPU, and strain remained above 2000%. Shape recovery went to as high as 97%, and remained almost same after repetitive shape recovery test cycles. Finally, the fluorescence emission of SMPU was demonstrated in the luminescence spectrum and fluorescent light emission pictures. In addition, the response of SMPU to external stimuli such as metal ions was investigated.

Characterisation and application of polyurethane copolymers grafted with photoluminescent dyes

“…Luminescent polymers have potential applications in safety marking systems, organic light‐emitting diodes, and luminescence converters for ultraviolet (UV)‐emitting diodes. In the present investigation, PU was grafted with PL dyes that were not tested previously by the authors . Then, a non‐woven PL‐PU fibre was prepared using the electrospinning method.…”

“…For example, a PU derivative that sustains shape recovery at −30 °C and an electrolytically responsive PU derivative that functions in water have been reported . Recently, the present authors have reported a PU series grafted with characteristic fluorescent dyes that exhibit unobstructed fluorescence together with high tensile strength . Similarly to the above‐mentioned grafted functional polymers, other characteristic fluorophores [aminofluorene (A), naphthalimide (NI), naphtholbenzein (NB), and phenosafranin (P)] need to be tested as promising functional molecules to graft onto PU chains, and the resultant photoluminescent (PL) PU derivatives can be used to prepare a non‐woven nanofibre using the electrospinning method.…”

Modification of polyurethane by graft polymerization of poly(acrylic acid) for the control of molecular interaction and water compatibility

“…This PU surface grafting method has been reported in the literature [18][19][20][21][22] and was previously demonstrated by our group in developing functionalized PUs; for example, PUs that exhibited flexibility at low temperatures [23], electric attraction in aqueous solutions [24], pH sensitivity [25], and photoluminescence [26] were successfully developed. Specifically, 2-hydroxyethyl methacrylate (HEMA), a vinyl group with a hydroxyl end, was attached to the PU side using MDI as a grafting agent.…”

“…The C=O stretching peaks at approximately 1700 and 1729 cm -1 were used to analyze the intermolecular interactions, such as hydrogen bonding and dipole-dipole interactions, between the hard segments. The bonded carbonyl band (1700 cm -1 ) appeared at a lower wavenumber than did the free carbonyl group band (1729 cm -1 ) [25,26]. The relative intensities of the bonded and free carbonyl stretching vibrations were used to compare the degree of phase separation (DPS) among the different series of polymers, which indicated the change in the molecular interactions between the hard segments.…”

Synthesis and characterization of fluorescein-grafted polyurethane for potential application in biomedical tracing

“…In this study, we grafted calcein markers using different polymerized procedures to investigate their fluorescent-loading effectiveness. Since previous studies have indicated that calcein-grafted materials could have long-lasting fluorescence, 19,20 we tried to explore the long-term fluorescent imaging of PU polymers using the copolymerization method. Physiochemical and fluorescent properties of calcein-loaded PU scaffolds have been evaluated and analyzed by different methods.…”