Ethanol and UV-assisted instantaneous bonding of PMMA assemblies and tuning in bonding reversibility

Here, we introduce an instantaneous and robust strategy for bonding poly(methylmethacrylate) (PMMA) substrates via ethanol treatment combined with subsequent UV irradiation under ambient conditions, and examine the bonding reversibility by varying the percentage of the ethanolic solution manufactured. Organic solvent such as ethanol can activate the surface of PMMA without sacrificing the optical property of the PMMA substrate, and a subsequent exposure to UV recrosslinks the diffused monomers of acrylate functionalities to realize permanent bonding of two PMMA substrates under mild and ambient experimental conditions, which minimizes the deformation of channel profiles. To achieve robust sealing, two PMMA substrates were immediately placed in direct contact with each other after the treatment with ethanolic solution, and were irradiated under UV. Permanent sealing was realized in less than 1 min. Various bonding analyses were conducted by performing tensile strength measurement, high-throughput leakage test, burst test, and peel test. The highest bonding strength was determined to be approximately 6.17 MPa when 90% ethanolic solution was employed, and the bonding was sufficiently robust to endure intense introduction of liquid whose per-minute injection volume was almost 1200-fold higher than the total internal volume of the microchannel adopted. We also investigated the potential in the manipulation of bonding reversibility, and the critical percentage of ethanolic solution to realize irreversible bonding for PMMA assemblies based on the proposed strategy was determined to be just over 50%.