Thermomechanical characterisation of cross-linked β-cyclodextrin polyether binders

Abstract

Cyclodextrins are promising building blocks for the synthesis of industrial binders. We determined the thermomechanical properties of a new binder prepared by cross-linking β-cyclodextrin with a variable amount of polyethylene glycol diglycidyl ether (40-60% w/w) to produce a soft polyether network that was soluble in water and alcohol. Increasing the amount of cross-linker reduced the glass transition temperature of the binder as determined by differential scanning calorimetry and dynamic mechanical analysis. Cooling experiments revealed sudden stress relief below the glass transition temperature, reflecting the de-bonding of the polymer from the metallic supports. This was prevented by contact with polytetrafluoroethylene tape. Optical microscopy confirmed the stress relief in the form of cracking and revealed self-healing by reptation, promoted by a higher cross-linker content and temperature. The influence of the support medium on the thermomechanical properties of the cross-linked β-cyclodextrins will help to optimise manufacturing and storage methods for new binders.

Chemical Modification of β‐Cyclodextrins: Balancing Soft and Rigid Domains in Complex Structures

“…The decomposition temperature ( T dec ) and glass transition temperature ( T g ) of the inert (IT, IH and IP) and nitrated (NT, NH and NP) samples were determined by differential scanning calorimetry (DSC) …”

“…The T dec (≈250 °C) was dependent on the length of the cross‐linker (Figure ), with higher values associated with IH samples. The decomposition temperatures of IP samples, containing long PEG cross‐linkers, were much lower than the expected trend, as previously reported . This reflects the polydispersity of the commercial PEGDGE, which also contains various shorter chains, resulting in a lower T dec in the blend compared to a pure compound with a similar molecular mass.…”

“…The self‐healing properties of the IP samples were discussed in our previous study . Here we assessed the self‐healing ability of a nitrated polymer sample (NP) with a PEG:βCD unit ratio of 4.0:1 (Figure a).…”

“…To overcome the sensitivity of βNCDs, we have recently developed new water‐soluble cross‐linked βCD structures containing soft PEG segments, and their nitrated counterparts . The cross‐linked βCD/PEG derivatives were prepared to improve resistance to accidental stimuli and facilitate processing as lacquers, as seen in formulations based on NC .…”

“…[33] To overcomet he sensitivity of bNCDs, [11] we have recently developedn ew water-soluble cross-linked bCD structures containing soft PEG segments, andt heir nitrated counterparts. [10,34] The cross-linked bCD/PEGd erivatives werep repared to improve resistance to accidental stimuli and facilitatep rocessing as lacquers, as seen in formulationsb ased on NC. [35] Here, we describe the development of two new sets of cross-linked bCDs (and their nitrated derivatives) using afamilyofdiglycidyl ethers with variable PEGs oft chains, andt heir comparison to the earlier bCD/PEGs tructures.…”