. Author manuscript; available in PMC: 2022 Jun 22.

Published in final edited form as: Chem Rev. 2021 Apr 12;121(8):4309–4372. doi: 10.1021/acs.chemrev.0c01088

Table 2.

Examples of unconventional polymer network interactions.

UPN interactions		Examples	References
Strong physical crosslinks	Crystalline domain	PVA treated by freeze-thawing or annealing	^{4,300,302,482}
		Chitin and chitosan treated by acidic or basic solutions	^215,218
		Cellulose treated by alkalines	^497,526,527
	Glassy nodule	Polystyrene-b-poly(N-isopropylacrylamide)-bpolystyrene	⁵³⁰
	Glassy nodule	Poly(methyl methacrylate)-b-poly(n-butyl acrylate)	⁴⁹²
	Helical association	Self-assemble of agarose or gelatin	^{6,103,534,535}
		Self-assemble of collagen or fibrinogen	^{6,103,532,533}.
		Self-assemble of elastin-like polypeptides	^507,510
Weak physical crosslinks	Hydrogen bond	PAA or polymethacrylic acid (PMA) with PEG	^{478,538–540}
	Hydrogen bond	PEG, PHEMA, PNIPAM with self-complementary hydrogen-bond groups (triazine moieties or ureido pyrinimidone moieties)	^{478,490,540–542}
	Electrostatic interaction	Alginate with Ca²⁺, Ba²⁺, Mg²⁺, Zn²⁺	^{6,103,105,546}
		Chitosan with tripolyphosphate, citrate ions	^547–549
		Cationic polyelectrolytes with anionic polyelectrolytes	^544,550
	Coordination complex	Bisphosphonate containing polymers with metal ions (Ca²⁺, Mg²⁺ or Ag⁺)	^557,572,573
		Catechol containing polymers with metal ions (Cu²⁺, Zn²⁺ and Fe³⁺)	^{478,574–577,580 560,561,578}
		Histidine containing polymers with metal ions (Cu²⁺, Co²⁺ and Ni²⁺)	^{478,579,58059}
	Host-guest interaction	Polymers containing β-CD moieties with azobenzene group, adamantyl group, ferrocene group, t-butyl group, cyclohexyl(ester) group, cyclododecyl(amide) group, benzyl group, 2naphthylmethyl group, 1-pyrenylmethyl group	^{383,457,478,540,586,588–594}
		Polymers containing α-CD moieties with n-butyl group, adamantyl group, benzyl group, trans- azobenzene group	^{383,478,540,586,587};
		Polymers containing curcubit[n]uril moieties with spermine, diaminohexane, viologens, naphtalenes	^{383,540,605,606}.
	Hydrophobic association	PEG, PAAm, PNIPAM, PDMAA, PVA containing hydrophobic moieties (octylphenol-PEG acrylate, stearyl acrylate, lauryl acrylate)	^{478,488,490 488,612,613}
	Hydrophobic association	Triblock amphiphilic copolymers with PEG, PAAm, PVA, PHEMA middle blocks and n-alkyl acrylate end blocks	^614–616
	π - π stacking	Polymers modified with aromatic moiety containing short peptides and N-terminal Fmoc- amino acids	^499,620,621
	π - π stacking	Hydrogels containing carbon nanotubes, polythiophene, and graphene-based nanomaterials	^30,622–626
Dynamic covalent crosslinks	Imine bond	Polymers containing amine and aldehyde (or ketone) functional groups	^{383,631–635,637–641}
	Boronate ester bond	Polymers containing boronic acid and diol functional groups	^{383,644,650,655,656,662}
	Disulfide bond	Polymers containing disulfide functional groups	^{383,615,668,674,675,679}
	Hydrazone bond	Polymers containing hydrazide and aldehyde (or ketone) functional groups	^{679,680,682–686,688–690}
	Oxime bond	Polymers containing hydroxylamine and aldehyde (or ketone) functional groups	^{695–698,706}
	Reversible Diels–Alder reaction	Polymers containing diene and dienophile functional groups	^701,711,712