I've been playing around with my mini rosetta recipe. I'm not sure, but the pairing properties of hydrophobic surfaces seem to display a pairing affinity similar to a Boolean AND gate.

AND
x1 x2 | result
00 | 0
01 | 0
10 | 0
11 | 1

r1 r2 | result
philic philic | repel (away from each other)
philic phobic | repel (away from each other)
phobic philic | repel (away from each other)
phobic phobic | attract (toward the center of the phobic core, and close to each other)