Polymershell

Polymershell refers to a polymeric outer layer that surrounds a core material, forming a core–shell structure. The shell is composed of polymers that can be covalently attached or physically associated with the core. The shell provides steric stabilization, controls solubility and permeability, and offers reactive sites for ligands or drugs. The thickness and composition of the shell determine the overall behavior, including biocompatibility and release properties. Shells can be homogeneous or crosslinked, and may be formed by grafting-from polymerization on the core surface, layer-by-layer deposition, self-assembly of block copolymers, or adsorption of preformed polymers.

Common materials include polyethylene glycol, poly(N-isopropylacrylamide), poly(acrylic acid), poly(lactic-co-glycolic acid), and natural polymers such as chitosan. Polymershells are widely used to cloak nanoparticles, liposomes, or inorganic cores, enabling prolonged circulation in vivo, targeted delivery, or protection of labile cores. In drug delivery, polymer shells can provide controlled release by environmental triggers such as pH or temperature, or by diffusion through the shell. In imaging, shells can bear targeting ligands or imaging agents. In catalysis or sensing, functional groups in the shell can recognize analytes or host active sites.

Characterization relies on TEM or cryo-TEM to measure core–shell geometry, dynamic light scattering and zeta potential for size and surface charge, FTIR or NMR for composition, and thermogravimetric analysis for shell mass. Synthesis challenges include achieving uniform shell thickness, controlling crosslinking density, and avoiding immune recognition.