Enhanced Templating in the Crystallisation of Poly(ε‐caprolactone) Using 1,3:2,4‐di(4‐Chlorobenzylidene) Sorbitol

Abstract

We show that small quantities of 1,3:2,4‐di(4‐chlorobenzylidene) sorbitol dispersed in poly(ε‐caprolactone) provide a very effective self‐assembling nanoscale framework which, with a flow field, yields extremely high levels of polymer crystal orientation. During modest shear flow of the polymer melt, the additive forms highly extended nano‐particles which adopt a preferred alignment with respect to the flow field. On cooling, polymer crystallisation is directed by these particles. This chloro substituted dibenzylidene sorbitol is considerably more effective at directing the crystal growth of poly(ε‐caprolactone) than the unsubstituted compound.

1,3:2,4-Dibenzylidene-d-sorbitol (DBS) and its derivatives – efficient, versatile and industrially-relevant low-molecular-weight gelators with over 100 years of history and a bright future

“…These authors then went on to show that chloro-substituted DBS was significantly more effective at directing this effect than unsubstituted DBS -an effect that they attributed to the lower solubility of the former compound. 94 It was also demonstrated that the presence of DBS could impact on the fibre dimensions and crystallinity of electrospun fibres of poly-(e-caprolactone). 95 Although in these studies the DBS was not removed from the polymer, there is clear potential to generate polymeric systems with aligned porosity in this way.…”

Controlling Morphology Using Low Molar Mass Nucleators

“…Figure 5.3 shows the phase behavior of the Cl-DBS/PCL system (Wangsoub et al 2008). The line for the crystallisation temperature shows that the addition of the Cl-DBS increases the crystallisation temperature by ~^10ºC due to the nucleating effect of the DBS derivative.…”

Controlling the Morphology of Polymers

“…A range of other derivatives can be readily formed by the acid catalysed reaction of sorbitol with the appropriate substituted aldehyde (e.g. benzaldehyde, benzaldehyde d 6 , or 4-chlorobenzaldehyde) in cyclohexane (Wangsoub, 2008). A typical procedure, that for 1,3:2,4-di(4-chlorobenzylidene) sorbitol (Scheme 5.2) was as follows.…”

“…In this work we used the shear flow cell (Nogales et al 2004) shown in Chapter 3 ( Figure 3.22) and for this, samples were prepared by co-solvent mixing, for example with PCL we employed butanone, drying and then melt pressing in to discs. Figure 5.3 shows the phase behavior of the Cl-DBS/PCL system (Wangsoub et al 2008). The line for the crystallisation temperature shows that the addition of the Cl-DBS increases the crystallisation temperature by ~^10ºC due to the nucleating effect of the DBS derivative.…”

“…In the case of highly aligned fibrils, consideration of the templating process reduces to a 2-d matter. The number density of fibrils is given by (Wangsoub et al 2008) 2…”