Oligo(∊-caprolactone)-Based Polymer Networks Prepared by Photocrosslinking in Solution

Abstract

The crosslinking condition of methacrylate functionalized precursors significantly affected network properties. For some types of precursors such as star-shaped telechelics, synthesis in solution provided semi-crystalline elastic materials that were not accessible from crosslinking in melt.

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

“…Oligo( ε ‐caprolactone) with hydroxyl end groups [oCL‐ol] of either linear ( 2 oCL) or four‐arm star‐shaped ( 4 oCL) structure were functionalized with 2‐isocyanatoethylmethacrylate (IEMA) to obtain 2 oCL‐IEMA (2, 3, 4, and 8 kDa) and 4 oCL‐IEMA (8 kDa) network precursors with high degrees of methacrylation D a (93%–98%, see Table S1, Supporting Information). Crosslinking in organic polymer solutions was selected as it is a state of high chain mobility, in which restrictions to chain folding or movement are very limited compared to conditions in melt with strong entanglements . In an integrated process of carrier and network formation, emulsion droplets of ethyl acetate solutions of oCL–IEMA precursors (o‐phase) in an external water (w‐) phase were prepared by vortexing as particle templates and subsequently exposed to UV irradiation (308 nm Excimer lamp) ( Figure ).…”

Morphology of crosslinked poly(ε-caprolactone) microparticles

“…Dispersion of oCL MP in an aqueous phase and performing the crosslinking in this suspension should further improve the accessibility of UV irradiation by separation of particle aggregates and reducing the chance of inter-particulate bonds. Despite photo-initiators are not necessary for this polymerization if high intensity laser light is applied [3,7], they are often employed for radical formation and to alter the rate of initiation and termination [8]. A bifunctional initiator as used here at high concentration to identify maximum effects should increase initiation events and reduce early termination in the diffusion controlled regime of polymerization [9].…”

“…Typically, the crosslinking of macroscopic samples is performed in the molten state or in solution [3]. When aiming to prepare smaller network matrices like microparticles [MP] as relevant for drug delivery, crosslinking is more challenging.…”

Photoinduced synthesis of polyester networks from methacrylate functionalized precursors: analysis of side reactions

“…When linear or four‐arm star‐shaped precursors are crosslinked either in the melt or in solution, network properties that are associated with the crosslink density can be altered. In addition to parameters such as the molecular weight and structure of the oligomeric telechelic, polymer network architecture was strongly influenced by the applied reaction conditions in the melt versus in solution . In this case, with more elastic materials being formed upon crosslinking in solution .…”

“…In addition to parameters such as the molecular weight and structure of the oligomeric telechelic, polymer network architecture was strongly influenced by the applied reaction conditions in the melt versus in solution . In this case, with more elastic materials being formed upon crosslinking in solution . In this context it should be considered that methacrylate‐based crosslinking may result in different distributions of netpoint functionalities based on the applied reaction conditions.…”