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Second-overtone carbonyl bands at 1918 and 2036 nm in the near-infrared (NIR) spectrum are used to monitor the phase separation of poly(ether urethane urea) (PEUU) block copolymers at 100°C. Exact positions of urea and urethane carbonyl bands are determined by NIR spectroscopic analyses of model compounds in bulk and in dilute solution. Results indicate that the carbonyl groups in the copolymers are affected by two different structural processes that occur with annealing. A faster process causes an increase in the number of free urethane groups, and a slower process causes a decrease in the number of free urea and urethane carbonyl groups. Although several structural mechanisms can be used to describe these trends, more information is necessary to identify exact structural changes that occur with annealing.

The purpose of the study was to assess the efficacy of a newly developed hydrogel tissue adhesive for sealing corneal incisions in ex vivo rabbit eyes. Simple through-and-through central linear corneal incisions measuring 1–5 mm were created in enucleated rabbit eyes. As controls, the leaking pressures were measured immediately after the incisions had been made. Afterwards, the incisions were sealed with hydrogel adhesive in group 1 and with a single 10-0 nylon suture in group 2. The leaking pressure of each incision was measured after the wounds had been sealed in both groups. The leaking pressures of the controls and the sealed incisions were compared for statistical significance using the Wilcoxon signed rank test. The difference between the leaking pressures before and after sealing the incisions in groups 1 and 2 were compared using the Mann-Whitney rank sum test. The leaking pressures were significantly higher after sealing in both groups 1 and 2 compared to the controls for all incision sizes. The differences in the leaking pressures before and after adhesive application were higher than before and after suturing in all incision sizes. The differences were all statistically significant except for the 1-mm incisions. We conclude that the hydrogel glue has the potential to be used for sealing corneal incisions measuring up to 5 mm.

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