Accelerated Self-Healing Via Ternary Interpenetrating Microvascular Networks
(4320–4326) Advanced Functional Materials 21  #22 (2011)
Hansen et al of the University of Illinois at Urbana-Champaign, Illinois, developed self-healing materials with dual interpenetrating microvascular networks which enable two-part healing chemistries and repeated healing of damage in a localized region.   However, due to slow healing kinetics, multiple days are required between damage events to recover mechanical performance under ambient conditions.  By directly writing a third interdigitated microvascular network within these epoxy coating/substrate architectures to enable in situ thermal regulation, the characteristic healing time is reduced by an order of magnitude.  Specifically, this third network provides a conduit for circulating a temperature-controlled fluid that rapidly heats the locally damaged region leading to a sharp reduction in the time required for mechanical property restoration.  (RDC 11/16/2011)

Evaluation of Norbornene-Based Adhesives to Amine-Cured Epoxy for Self-Healing Applications
(965–972)Macromolecular Materials and Engineering 296 #10 (2011)
Huang, Lee and Kessler of Kumoh National Institute of Technology, South Korea and owa State University, Iowa triggered healing by crack propagation through embedded microcapsules in an epoxy matrix, which then release the liquid healing agent into the crack plane.  Subsequent exposure of the healing agent to an embedded chemical initiator triggers ring-opening metathesis polymerization (ROMP), bonding the crack faces closed.  The healing agents tested include endo-dicyclopentadiene (DCPD), 5-ethylidene-2-norbornene (ENB) and DCPD/ENB blends. 5-Norbornene-2-methanol (NBM) and 5-norbornene-2-exo,3-exo-dimethanol (NBDM) were used as adhesion promoters because they contain hydroxyl groups which can form hydrogen bonds with the amine-cured epoxy adherend.  (RDC 10/13/2011)

MD SIMULATION OF SINGLE-WALL CARBON NANOTUBES EMPLOYED AS CONTAINER IN SELF-HEALING MATERIALS
(333-338) Polymers and Polymer Composites 19 #4-5 (2011)
Liu, Liu and Wang proposed self-healing models enclosing styrene molecules into carbon nanotubes (CNTs) are proposed because of the unique hollow structure and predominant properties of CNTs.  The nanotubes filled with healing agent are embedded in an epoxy matrix which contains catalyst particles capable of polymerizing the healing agent. When a micro crack forms in the matrix and ruptures the wall of single-wall nanotube (SWNT), the healing agent escapes from SWNT. The polymerisation of healing agent is triggered once it contacts with the catalyst which is embedded in polymer matrix, and rebind the damaged site. Then the healing process is completed. One of the key points of this self-healing process is whether the healing agents can escape from the wall of SWNTs. In order to probe whether the feasibility of this system, models have been set up using molecular dynamics. The results of our simulations have shown that the healing agents can escape from the SWNTs in 5 ps, and the number of escaped styrene molecules depends on temperature and the density of the styrene molecules that filled into nanotube.  (RDC 6/24/2011)

PREPARATION AND CHARACTERIZATION OF SELF-HEALING POLYMERIC MATERIALS WITH MICROENCAPSULATED EPOXY AND IMIDAZOLINE DERIVATIVES CURING AGENT
(279-288) Polymers and Polymer Composites 19 #4-5 (2011)
Wang et al studied binary self-healing system consisting of epoxy-containing microcapsules and latent curing agent based on anionic polymerisation.  When cracks propagated in the composites, the embedded microcapsules would be damaged and the epoxy healing agent would be released.  The latent curing agent used in this study can be well dispersed in epoxy matrix during composites manufacturing, and hence activate the released epoxy wherever it is. As a result, self-healing of the cracked sites is successfully achieved through curing of the released epoxy healing agent.  (RDC 6/24/2011)