Branched PEG acid is a type of polyethylene glycol (PEG) acid that has been modified to contain multiple branches of PEG molecules, rather than a single linear chain. These branches make the molecules more soluble in water and allow them to bind to surfaces more strongly than unbranched PEG molecules. Branched PEG acids are commonly used in biomedical applications, such as drug delivery, wound healing, and tissue engineering.