Photoreversible Chain Extension of Poly(ethylene glycol)

Abstract

Summary: Coumarin containing poly(ethylene glycol) monols and diols were prepared in a telechelic fashion using quantitative end group esterification. The coumarin modified poly(ethylene glycol) monols and diols were solution cast into films (1 to 15 μm) and chain extended via the dimerization of the coumarin derivatives with UVA (>300 nm) light irradiation. The coumarin‐modified PEG diol doubled in molecular weight, and the molecular weight distribution increased from 1.17 to 2.75 upon exposure to 110 J · cm−2 of UVA light. The chain extended poly(ethylene glycol)s were subsequently converted to their original molecular weight via the photocleavage reaction of the coumarin dimer at 254 nm with less than 2 J · cm−2. The photoreversible chain length modulation was monitored utilizing GPC, DSC and UV‐Vis spectroscopy.Molecular weight modulation of COU‐PEG‐COU.magnified imageMolecular weight modulation of COU‐PEG‐COU.

Coumarins in Polymers: From Light Harvesting to Photo-Cross-Linkable Tissue Scaffolds

“…185 PEG monols were quantitatively functionalized with 7-hydroxycoumarin acid chlorides ( Figure 24) then solvent cast from chloroform onto glass microscope slides. UVA irradiation of the films dimerized and chain-extended the PEG molecules as observed with UV-vis spectroscopy (Figure 25a).…”

Photoactive Polyesters Containingo-Nitro Benzyl Ester Functionality for Photodeactivatable Adhesion

“…Long et al recently developed polymers containing photodegradable units and photoreversible adhesives [3,[23][24][25][26][27][28]. In particular, we demonstrated the utilization of cinnaPolyesters for Photodeactivatable Adhesion 549 mate [23,24], coumarin [25][26][27][28], and cyclobutane diimide functionalities [3] towards the development of photoreactive coatings and adhesives. In addition, our group published research detailing the synthesis of star-shaped acrylic polymers with an acid labile core [6].…”

Synthesis and characterization of coumarin-containing polyphosphazene

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