6533b834fe1ef96bd129e035

RESEARCH PRODUCT

Spontaneous symmetry-breaking pathways: time-resolved study of agarose gelation

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Abstract Extensive time-resolved studies of self-assembly of agarose gels, performed with the use of a variety of techniques allowed identification of the initial break of symmetry and the actual path leading to self-assembly at concentrations well below the random percolation threshold. The overall process is seen to occur through the following sequence: (i) break of symmetry in the sol, causing the spontaneous generation of mesoscopic polymer-rich and solvent-rich regions; (ii) percolation, or nearly percolation [see (iv) below], of polymer-rich regions through the sample, still in the sol state; (iii) start of polymer cross-linking within polymer-rich regions; (iv) progress of cross-link percolation, channeled along the pathways of polymer-rich regions. The analogous role of either permanent or transient demixing of the sol in providing preferential paths for cross-links and promoting gelation at moderate and low concentrations has been established also in a variety of other biopolymeric systems.