A team from Oklahoma report the fabrication of non-leaching antibacterial surfaces using a single-step vapour crosslinking method.
Single-step fabrication of non-leaching antibacterial surfaces using vapor crosslinking
Yumin Ye, Qing Song and Yu Mao
J. Mater. Chem., 2010, Advance Article
DOI: 10.1039/C0JM02578J, Paper
Bactericidal surfaces are highly desirable to prevent bacteria-associated infections in hospital and health care facilities. Current surfaces are based on the release of antibacterial agents, however, leaching of antibiotics can contribute to the escalation of bacteria resistance. An alternative strategy is to create non-leaching antibacterial surfaces. The non-leaching surfaces kill bacteria on contact, which has been reported to reduce the probability of developing bacteria resistance.
Yu Mao and colleagues copolymerised vapours of dimethylaminomethylstyrene (DMAMS) and ethylene glycol diacrylate (EGDA) to produce crosslinked polymer coatings. The tertiary amine groups in DMAMS units become partially protonated at neutral pH conditions, resulting in crosslinked coatings which have cationic charges distributed across the polymer network and kill bacteria through disruption of the bacteria membrane upon surface contact. Killing efficacy of more than 99.99% against both B. subtilis and E. coli was achieved and leaching tests indicated that the crosslinked coatings did not leach from the surface to kill bacteria and were stable after the durability tests.
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Erin Murphy from the University of California reports the use of birefringence to assess damage and extent of repair in healable polymers based on the thermally reversible Diels–Alder reaction, in this ‘Hot Article’.
The return of photoelastic stress measurements: utilizing birefringence to monitor damage and repair in healable materials
Erin B. Murphy
J. Mater. Chem., 2011, Advance Article
DOI: 10.1039/C0JM02308F, Paper
Examining a transparent polymer under polarized light reveals the stress distribution throughout the sample due to the birefringence in the material arising from anisotropy, clearly indicating areas of high stress; by applying a photoelastic coating to metal and opaque composite structures, it is also possible to identify areas of stress in non-transparent materials and parts.
Herein, Erin Murphy demonstrates the application of birefringence and the principles of photoelastic stress measurements to monitor a healable polymer. By systematically monitoring the birefringence of the material under a controlled applied stress, her group have developed their own calibration curve for the analysis of isochromatic fringes in the polymers.
The birefringent property of these polymers affords the ability to analyze residual stress in a fabricated sample, in order to assess the sites most likely to fracture and to then re-design the specimen geometry and processing parameters to avoid such areas within the material.
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