Polyquaternium-81 is an anti-static ingredient. Shampooing leaves a negative charge on the hair which can make it difficult to manage. The function of Polyquaternium-88 is to leave a positive charge on the hair instead, making it more well-behaved and easier to comb.
The Polyquaternium-81 that Lush uses is safflower, coconut oil and corn derived. Sourced from a family-run business, the materials are made with absolutely no animal testing involved.