. Author manuscript; available in PMC: 2021 Sep 24.

Published in final edited form as: Adv Drug Deliv Rev. 2020 Sep 24;156:80–118. doi: 10.1016/j.addr.2020.09.009

Table 1.

Hydrophilic polymers commonly used for constructing amphiphilic block copolymers.

Polymer	Synthesis	Properties and comments	Ref

PEG¹	Living anionic ring-opening polymerization (ROP) of ethylene oxide	Most often used hydrophilic polymer with stealth property. Used in clinically approved nanoformulations including polymer micelle (Genexol^®PM). Potential immunogenicity and accelerated blood clearance (ABC) phenomenon. The only shell-forming polymer that is used in clinically approved products as of today.	[40–43]
Poly(2-oxazoline)s	Living cationic ring-opening polymerization (LCRP) of 2-oxazoline monomers	Both polymers are evaluated as PEG replacement PMeOx is more hydrophilic than PEG.	[22, 44–46]
Poly(sarcosine)	Living polymerization of α-amino acid-N carboxyanhydrides	Evaluated as PEG replacement. Biodegradable.	[47–49]
Polysaccharides	Enzymatic synthesis	Used as a component in block and graft copolymers. Highly variable molecular weight. Dextran has been used as excipient in clinically approved injectable products (FERAHEME^®). Biodegradable.	[50–53]
Miscellaneous	Atom transfer radical polymerization; reversible addition fragmentation chain transfer	Potential immunogenicity noted (PVP). Nonbiodegradable.	[57–64]