You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Barnacle Cement as Surface Anchor for 'Clicking' of Antifouling and Antimicrobial Polymer Brushes on Stainless Steel. Barnacle cement (BC) was utilized 'beneficially' as a surface anchor on stainless steel (SS) for coupling of functional polymer brushes via 'click' reactions in both "grafting-to" and "grafting-from" processes. Ethylene sulfide (ES), propargyl carbonylimidazole (PPC) and azidoethyl carbonylimidazole (AEC) reacted with amine and/or hydroxyl groups in BC to introduce the corresponding thiol, alkyne and azide groups on SS surfaces (SS-thiol, SS-alkyne and SS-azide, respectively). Antifouling zwitterionic SS-PMPC surface was prepared by thiol-ene photopolymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) from the SS-thiol surface. Protein-resistant SS-PPEGMA and protein-adsorbing SS-PPFS surfaces were prepared by coupling of the respective azide-functionalized poly(poly(ethylene glycol)methyl ether methacrylate) (azido-PPEGMA) and poly(2,3,4,5,6-pentafluorostyrene) (azido-PPFS) polymer brushes in azide-alkyne 'click' reaction. Antifouling alkyne-functionalized poly(N-hydroxyethyl acrylamide) (alkynyl-PHEAA) and antibacterial alkyne-functionalized poly(2-(methacryloyloxy)ethyl trimethylammonium chloride) (alkynyl-PMETA) polymer brushes were clicked on the SS-azide surface. Adsorption of bovine serum albumin and bacteria fouling of Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus epidermidis (S. epidermidis) were investigated on the polymer-functionalized SS surfaces. The versatile bio-anchor and functional polymer brush coatings are stable in abiotic aqueous environment for over a month.
{"Chemical": ["Ethylene sulfide", "poly(poly(ethylene glycol)methyl ether methacrylate)", "poly(2,3,4,5,6-pentafluorostyrene)", "PPEGMA", "azide", "AEC", "azidoethyl carbonylimidazole", "hydroxyl", "2-methacryloyloxyethyl phosphorylcholine", "azido-PPFS", "alkynyl-PHEAA", "poly(N-hydroxyethyl acrylamide)", "PPFS", "alkyne", "alkynyl-PMETA", "propargyl carbonylimidazole", "MPC", "PPC", "thiol", "amine", "poly(2-(methacryloyloxy)ethyl trimethylammonium chloride)", "azido-PPEGMA"]}