Method for Preparation, Programming, and Characterization of Miniaturized Particulate Shape-Memory Polymer Matrices

Abstract

Their capability to change their shape on demand has created significant interest for shape-memory polymers (SMPs) in minimally invasive surgery. To evaluate the miniaturization of SMP matrices for small-sized implants or controlled release systems, a strategy to prepare and evaluate microsized SMP model particles is required. This methodological study reports the emulsion-based preparation of ~30 μm microparticles (MPs) from a phase-segregated SMP, poly(ε-caprolactone) [PCL] and poly(ω-pentadecalactone) [PPDL], with a particular focus on the effects of process parameters such as polymer solvents or stabilizer type/concentration on formation and size distribution of SMP MPs. Processes for the preparation of SMP MP-loaded water-soluble polymer films with tailored mechanical properties were developed and applied for programming the SMP MP to a temporary ellipsoid shape by film stretching. For the functional evaluation of shape recovery of MPs, a light microscopy-based setup with temperature control is proposed by which the stimuli-induced switching of the microsized SMP matrices could be confirmed. Overall, by applying this methodological strategy to various thermoplastic SMPs, a routine to identify and characterize the microscale functionality of SMPs in miniaturized applications will be broadly accessible.

Recent progress in shape memory polymer: New behavior, enabling materials, and mechanistic understanding

“…In 2014, Lendlein's group reported the first shape memory microparticle system [139,140]. In their work, microparticles with diameters around ∼30 µm were prepared using an oil-in-water (o/w) emulsification method.…”

Polymer Micronetworks with Shape‐Memory as Future Platform to Explore Shape‐Dependent Biological Effects

“…In this process, samples are transferred by external stress from their permanent, here the spherical micronetwork shape, into a temporary, here ellipsoid shape. In order to allow elastic deformation of numerous micronetworks simultaneously, PVA film matrices called phantoms were used to embed micronetworks. The phantoms were stretched to defined elongations ε ph at T high = 70 °C, which allows continuity of displacement of particulate inclusions since micronetworks are in the viscoelastic, soft state at T high > T m,PCL .…”

Characterization of Langmuir Films Prepared from Copolyesterurethanes Based on Oligo(ω‐pentadecalactone) and Oligo(ε‐caprolactone) Segments

“…Their hydrolytic and enzymatic degradability and reasonable biocompatibility has made aliphatic (co)polyesters a favored implant material for surgical and pharmaceutical applications . Recently poly(ω‐pentadecalactone) (PPDL) has attracted attention as a new member of this material class because of its thermoplastic processability and its higher melting point than poly(ε‐caprolactone) (PCL) . Copolyesters from ω‐pentadecalactone and other lactones such as ε‐caprolactone are explored for biomedical applications.…”