Hydrophilic concentrated polymer brushes decrease ice adhesion only when polymer-bound water is maintained in the grafted layer and this layer is not stripped under repeated shear. This work studies non-ionic poly(ethylene glycol) methyl ether methacrylate (PEGMA) brushes on silicon and establishes the density--hydration regime separating transient reduction in adhesion from durable ice release. Brush samples are prepared in the range of normalized surface occupancy from $\text{sigstar}=0.004$ to 0.46 and in dry thickness from 10 to 831 nm. Ice adhesion is measured at $-18{}^{\circ }C$ and at lower temperatures following water freezing in a 6 mm ice pillar; microscopic FT-IR spectroscopy is used to measure local hydration near droplet and ice edges; DSC measures non-freezing water content. In low-density brushes, adhesion is decreased relative to silicon substrate but the film is stripped off during repeated cycles of ice release, while brushes with $\text{sigstar}\ge 0.15$ preserve the grafted layer and show sustained reduced adhesion. The $\text{sigstar}=0.38$ brush retains both film thickness and its ice-release performance during 10 cycles. Within the concentrated range, the ice adhesion at $-18{}^{\circ }C$ does not change for dry film thicknesses from 25 to 831 nm, indicating that the key role is played by the dense hydrated grafted layer rather than the total dry thickness. FT-IR microscopy shows that during the cooling process, the water droplet edge swells more with increasing supercooling, but the extent decreases from $S=2.8$ to $S=0.9$ once droplets and precursor regions freeze. Following holding at $-40{}^{\circ }C$, $S$ value for the region adjacent to the ice is $S\approx 0.7$. According to DSC, the non-freezing water fraction equals $\text{WNFW}/\text{WP}\approx 0.54\pm 0.1$, i.e., about 1.6 water molecules per ethylene oxide unit. Durable ice release therefore takes place only when dense grafting retains a hydrated polymer layer with the residual water content higher than the non-freezing water fraction. Increasing adhesion at $-30{}^{\circ }C$ results from narrowing of the interphase due to retention of water.

PEGMA,concentrated polymer brush,ice adhesion,nonfreezing water,FT-IR microscopy,differential scanning calorimetry,graft density,interfacial hydration.