Table 4. Roughness Values of PUs before and after Water Immersion.

	PEG 0%		PEG 30%
cross-linked	Rq (nm)	Ra (nm)	Rq (nm)	Ra (nm)
before water immersion	19.5	17.0	33.2	26.1
after water immersion	19.1	15.8	49.9	39.5
linear	Rq (nm)	Ra (nm)	Rq (nm)	Ra (nm)
before water immersion	16.8	13.7	24.5	18.9
after water immersion	17.3	14.4	37.1	29.6