Thiol-Functionalized Poly(ω-pentadecalactone) Telechelics for Semicrystalline Polymer Networks

Abstract

Semicrystalline macromonomers based on poly(pentadecalactone), PPDL, have been synthesized by the lipase-catalyzed ring-opening of the otherwise chemically inert pentadecalactone monomer. The macromonomers were designed to have reactive thiols as end groups by the appropriate choice of initiator and chain terminator. The thiol functional macromonomers were then used together with ene monomers to give crosslinked thin films after irradiation in the molten state by UV light in the presence of a photoinitiator (Irgacure 651). Two different ene monomers were used, i.e., a tetrafunctional norbornene species and a trifunctional allyl ether maleate species, and resulted in semicrystalline cured films when cured with PPDL. An amorphous, commercially available, trifunctional thiol, trimethylolpropane tri(3-mercaptopropionate), TRIS, was also used for network formation in order to better understand the effect of crystallinity. All thiol-ene systems were found to be readily photopolymerised to high conversion. The PPDL-based networks were semicrystalline in the crosslinked state where the degree of crystallinity was found to depend on the nature of the cross-linker. Networks based on TRIS were found to be amorphous.

Green process for green materials: viable low-temperature lipase-catalysed synthesis of renewable telechelics in supercritical CO 2

“…Similar differences have been encountered by other groups, when using GPC with PSt standards for polyester analysis (9,11,65). Nevertheless, the dispersity values are mostly around 2, which is a value typically expected for linear polycondensations at high conversions and already found by other groups when synthesising low molecular weight telechelics (9,15,65,66). The 1 H-NMR spectra clearly show that the end-group functionalities are incorporated into the polymer chains and are unaffected during the synthesis mainly as a result to the low reaction temperature (35°C) achieved by using scCO2.…”

“…Recently, great importance has been given to low molecular weight (between 1000 and 4000 g/mol) telechelic polyesters (8)(9)(10)(11). These are functional polymers that carry the same functional group at both ends (12) and find applications in surface modification (8,9), medical materials (13), block copolymer formation (14), cross-linked networks (10,15) etc. Low molecular weights are often desirable in order to obtain low-viscosity materials and good filmability (8,10,11).…”

“…Low molecular weights are often desirable in order to obtain low-viscosity materials and good filmability (8,10,11). Furthermore, if a cross-linkable system is the desired product, low molecular weight between the reactive moieties is necessary in order to achieve a high cross-link density and therefore a tougher network (8,10,15). To achieve a fully green process, enzymes have been exploited as substitutes for metal-based catalysts that are potentially toxic (16)(17)(18)(19), expensive, and require high temperatures (normally greater than 160°C for polycondensations) to work effectively (20)(21)(22)(23)(24).…”

Hydrolases Part I: Enzyme Mechanism, Selectivity and Control in the Synthesis of Well-Defined Polymers

“…This has important consequences in preparation of α, ω-functionalized polyesters, which are currently being explored in a variety of applications [111,112]. A systematic study by Heise and coworkers on the initiating efficiency of different initiators (1-3 in Fig.…”

The preparation and physical properties of polysulfide-based elastomers through one-pot thiol-ene click reaction

“…In recent years, some new oligomeric thiols have been synthesized and incorporated into thiol-ene networks, which opens up new applications or provides improved properties. For example, the synthesis of dithiol polyester and its incorporation into thio-ene networks brings a new opportunity for creating semicrystalline networks [18][19]. The use of oligomeric thiols has the distinct advantage of low shrinkage and a reduction in stress during the photopolymerization process [20] or lower glass transition temperatures and more uniform networks [21].…”