Magnus Eriksson

Enzymatic One-Pot Route to Telechelic Polypentadecalactone Epoxide : Synthesis, UV Curing, and Characterization

In an enzymatic one-pot procedure immobilized lipase B from Candida antarctica was used to synthesize semicrystalline diepoxy functional macromonomers based on glycidol, pentadecalactone, and adipic acid. By changing the stoichiometry of the building blocks, macromonomers of controlled molecular weight from 1400 to 2700 g mol(-1) could be afforded. The enzyme-catalyzed reaction went to completion (conversion >or=95%) within 24 h at 60 degrees C. After removal of the enzyme, the produced macromonomers were used for photopolymerization without any purification. The macromonomers readily copolymerized cationically with a cycloaliphatic diepoxide (Cyracure UVR-6110; CA-dE) to high conversion. The cross-linked copolymers formed a durable film with a degree of crystallinity depending on the macromonomer size and amount of CA-dE used, without CA-dE the macromonomers homopolymerized only to a low degree. Combined with CA-dE conversions of 85-90% were determined by FT-Raman spectroscopy. The films became more durable once reinforced with CA-dE, increasing the cross-link density and reducing the crystallinity of the PDL segments in the films.

One-pot enzymatic polycondensation to telechelic methacrylate-functional oligoesters used for film formation

Based on largely renewable monomers, an enzymatic one-pot polycondensation route towards functional oligomers with targeted molecular weights and end-groups was developed. This one-pot synthesis was performed by combining Candida antarcticalipase B (CALB), 2-hydroxyethyl methacrylate (HEMA), ethylene glycol, and divinyl adipate under reduced pressure (72 mbar) at 60 °C. The polymerization went to completion (>95% conversion for all monomers) within 24 h and the fraction of methacrylate end-groups was >90%. Three targeted dimethacrylate functional oligomers with molecular weights of 920, 1700 and 2500 g mol−1 (degrees of polymerization 4, 8, and 13 respectively) were synthesized. The oligomer products were characterized by NMR, MALDI-TOF MS and SEC. The dimethacrylate functional oligomers were further UV homopolymerized or combined with a tetrathiol crosslinker to demonstrate the potential to produce novel networks with tunable thermal properties dependent on chain length of the telechelic building blocks. This research is the first to demonstrate methacrylate functionalization and condensation polymerization in a one step process, which expands the growing toolbox for polymer/material chemists towards an increased throughput in available macromonomers used in material design.

Grouting field experiment at the Äspö Hard Rock Laboratory

This paper presents a field experiment in grouting a fracture at the Aspo Hard Rock Laboratory in Sweden. The fracture was investigated and described in terms of transmissivity, from which a prediction of grout spread was made, based on calculations that included a model for the penetrability of cement-based grouts. In the practical part of the experiment, the fracture was grouted and separated from the rock so that visual and chemical investigations could be performed. The grout spread evaluated from the separated fracture was found to agree with the prediction. It was verified that the grout spread was halted by the limited penetrability of the grout, which was in accordance with the prediction.

The Concepts of PARPS : Packet and Resource Plan Scheduling

Dynamic schemes for downlink packet radio resource management (RRM) are the topic of this paper. The concept of PARPS (Packet And Resource Plan Scheduling) is introduced. PARPS reduces the combined ...