Biobased acrylate shells for microcapsules used in self-healing of cementitious materials


Type
Article
Change log
Authors
Ribeiro De Souza, Livia  ORCID logo  https://orcid.org/0000-0002-0241-2880
Whitfield, Briony 
Al-Tabbaa, Abir 
Abstract

To facilitate the ongoing transition towards carbon neutrality, the use of renewable materials for additive manufacturing has become increasingly important. Here we report for the first time the fabrication of microcapsules from biobased acrylate shells using microfluidics. To select the shell, a wide range of biobased acrylates disclosed in the literature was considered according to their tensile strength, ductile transition temperature and global availability. Once acrylate epoxidised soybean oil (AESO) was selected, its viscosity was adjusted to valuables suitable for the microfluidic device using two different diluting agents. Double emulsions were successfully produced using microfluidics, followed by photopolymerisation of the shell and characterisa-tion of the capsules. Microcapsules containing AESO and isobornyl acrylate (IBOA) were pro-duced with an outer diameter ~ 490 μm, shell thickness ranging between 36 and 67 μm, and production rates around 2.4 g/h. The mechanical properties of the shell were characterised as tensile strength of 29.2 ± 7.7 MPa, Young’s modulus of 1.7±0.4 GPa and the ductile transition temperature was estimated as 42°C. To investigate physical triggering, microcapsules produced with a size of 481 ± 4 μm and with a measured shell thickness around 6 μm were embedded in the cementitious matrix. The triggered shells were observed with scanning electron microscopy (SEM) and the uniform distribution of the capsules in cement paste was confirmed using X-ray computed tomography (XCT). These advances can facilitate the wide application of biobased resins for the fabrication of microcapsules for self-healing in cementitious materials.

Description
Keywords
Journal Title
Sustainability
Conference Name
Journal ISSN
2071-1050
Volume Title
Publisher
MDPI AG
Sponsorship
Engineering and Physical Sciences Research Council (EP/P02081X/1)
Aspects of this work reported here was carried out as part of an MEng research project by the second author [35]. The authors also acknowledge the financial support provided to the first au-thor from the UKRI-EPSRC, grant number EP/P02081X/1 (Resilient Materials 4 Life, RM4L).