The project “Biobased Resin Components for Sustainable Development of Fastening Technology in Construction Chemistry” was carried out from 1 April 2019 to 30 June 2022 by the Leibniz Institute for Polymer Research Dresden (IPF) together with an industrial partner. The aim was to develop new biobased resin components that could replace conventional oil‑based resin cores in two‑component (2 K) chemical mortars while maintaining comparable mechanical performance. The funding was provided by the German Federal Ministry of Education and Research (BMEL/FNR) under the grant code 22011618.
The technical work focused on the synthesis of a range of biobased resin precursors derived from isosorbide, galactose‑tartrate, mannitol, gluco‑furanose, xylo‑furanose, and other sugars, as well as biobased reactive diluents. A key innovation was the use of a simple, scalable esterification protocol in which biobased diols were reacted with commercially available methyl methacrylate (MMA). This method delivers near‑quantitative yields without the need for additional solvents; excess MMA serves as an efficient reaction medium and is removed together with methanol by distillation. The process operates in the presence of heterogeneous solid catalysts that can be removed by filtration, avoiding complex purification steps such as extraction or column chromatography. The resulting methacrylate‑functionalized compounds—examples include DMA‑GalX‑Amidol, DMA‑GalX‑NMeCH₂CH₂‑OH, Tetra‑MA‑GalX, UMA‑GalX‑Amidol, DMA‑DiPrM, DMA‑iPrXF, Tri‑MA‑iPrGF, and 1,5‑Pentandiol‑dimethacrylate—were produced successfully under standard conditions. Only the betulinol derivative required an alternative route involving methacryloyl chloride because one of its hydroxyl groups was poorly reactive.
Scale‑up experiments were performed at 25–100 g for preliminary network and mechanical testing at IPF, and at 100–400 g for delivery to the industrial partner. Mechanical characterization of the cured resins, including compression tests and dynamic mechanical analysis, showed promising results, indicating that the new methacrylates could replace conventional resin cores without loss of strength. The most promising components were further tested in 2 K mortar formulations by the industry partner, where they were incorporated into prototype dowel masses. These prototypes exhibited mechanical properties comparable to reference mortars based on oil‑derived components.
Parallel to synthesis, the project advanced analytical methods for real‑time monitoring of the curing process. Near‑infrared (NIR) spectroscopy and rheology were optimized to provide reproducible measurements. By reducing the sample thickness from 5 mm to 1 mm, temperature and shrinkage effects were minimized, leading to a reduction in the variation of the reaction time (t₍turn₎) from 2.14 min to 0.35 min and of the conversion parameter U from 14 % to 5 %. Differential scanning calorimetry (DSC) was also employed for reaction monitoring and resin characterization. The inhibitor concentration (TEMPOL) was set to 0.13 mol % to achieve a curing time of approximately 5.5 min.
The project experienced several schedule adjustments due to the COVID‑19 pandemic, including the cancellation of one work package and the postponement of others. A cost‑neutral extension until 30 June 2022 was granted to accommodate these changes. Despite these challenges, the collaboration between IPF and the industrial partner successfully produced a portfolio of biobased resin components, validated their performance in mortar systems, and established scalable synthesis and monitoring protocols that can be transferred to industrial production.