Table 5. Summary of the Principal Properties of the PHU-Based Coatings Reported in Academia^aa.

type of coating	substrates	curing/application conditions	film hardness	solvent resistancea	chemical resistance	cross-cut adhesion	others	ref
solvent-free	glass	160 °C, 16 h					140 GUj	(65)
solvent-free	glass	80 °C, 14 h					scratch resistant	(66)
solvent-free	glass	120 °C					19.9–31.2°k,l	(40)
							19.1–32.3°k,l	(39)
							12.5–61.1°k,l	(67)
							58–79°k	(68)
solvent-free composite	bare and anodized Al	70 °C, 12 h + 100 °C, 3 h		>350		5BASTM	>85°k	(62)
	Al			>200		5BASTM	>95°k	(63)
solvent-free	Al	100 °C, 18 h				5BASTM	57–61°k	(38)a
solvent-free	tin	120 °C, 6 h	HPe			0ISO	60e	(69)
							504 hm
							>106.8°k
solvent-free	pine	130 °C, 24 h					49.2°k	(41)
		300 °C, 5 min				5BASTM,o	62.3°k
solvent-based	cold-rolled steel (CRS)	150 °C, 3 h			ac., alk., DMF, eth, acetone	poor		(70)
solvent-based		80 °C, 45 min + rt, 7 days	172Kö	>300				(71)
solvent-based	steel, glass	rt, 1 h, 80 °C, 2 h				5BASTM		(72)
solvent-based	mild steel	150 °C, 10–30 min	2H–3HPe	>200b	H2O, ac., alk.	2.37–2.83c	70d	(73)
solvent-based	mild steel	150 °C, 5 min	4HPe	>200b	ac., alk.	5BASTM,4.9c	70d	(74)
							>1000f
solvent-based	CSRg	150 °C, 30 min + rt, 7 days	3H–6HPe, 160–178Kö	>300	H2O, DEET, alk., aro. fuel, hy. fl. not to ac.	5BASTM, 2–4BASTM,h	faili 10–30d	(75)
solvent-based	tin	100 °C, 30 min	2HKö		poor H2O, EtOH, ac., alk.	1ISO	<10e	(76)
solvent-based	bare steel	120 °C, 3 h	65Kö, 2HPe	>400		5BASTM	172d	(77)
solvent-based	mild steel	140 °C, 1 h	>H		ac. poor: alk.	5BASTM	71d	(78)
							NaClt
solvent-based	glass	spin-coating					B. Subtilisn	(79)
							E. colin
solvent-based	glass	rt, 2 h + 60 °C, 16 h					Gram-positive,n Gram-negativen	(80, 81)
water-borne	tin	90 °C, 1–2 h + 120 °C, 2 h	HB–3HPe,p		xy, to, EtOH, ac. bad to alk.	0–1ISO	optimal gloss values	(87)
			HPe,p, 0.74Pen,p			0ISO	70e	(88)
water-borne hybrid	glass	rt, 12 h + 100 °C, 2 h or rt, 7 days	2BPe, 14Kö	>100			>80e	(89)
water-borne	Al	60 °C, 2 h + 120 °C, 2 h + 160 °C, 2 h	3HPe			1ISO	35–68°k	(90)
radiation-curable	tin	UV-cured, rt, 30 min	2H–2B			5B–4BASTM		(98)
radiation-curable	Al	UV-cured + rt, 3 days	2B–HBPe	>200			88–92e	(99)
radiation-curable	steel	UV-cured					25.5Young	(100, 101)
radiation-curable	polyester textile	UV-cured + 50 °C, 24 h at 75% RH					>30 washing cycles	(102)
radiation-curable	Al 2024-T3	UV-cured, 3 passesq		85–90	H2O, hy. fl. poor: aro. fuel, lub. oil		–54 °C, passedi	(103)
PHU–epoxy hybrid		rt, 5–8 days	2HPe		ac., alk., NaClr	4BASTM	50e	(97, 105, 106)
PHU–epoxy hybrid	Al	60 °C, 2 h + 120 °C, 2 h	4H–5HPe			1ISO		(90)
PHU–epoxy hybrid	CRS	rt, 7 days		100	aro. fuel, hy. fl., lub. oil	5BASTM	–54 °C, passedi	(109)
PHU–nanocomposite hybrid	Al	75 °C, 24 h		190		5BASTM	gloss 70–100e	(116)
PHU–nanocomposite hybrid	Al	100 °C, 24 h				1ISO	gloss 132–140	(107)
PHU–POSS hybrid	Tin	100 °C, 8–12 h	2H–3H			1ISO	50e	(117, 118)
PHU–POSS hybrid	glass	80 °C, 14 h + 100 °C, 4 h					scratch resistants	(119)
PHU–silica hybrid	carbon steel	130–140 °C, 3 h			H2O, ac. poor: alk.	5BASTM	flame retardant	(120)
PHU–Ly–gibbsite hybrid	stainless Steel	80 °C, 24 h + 100 °C, 4 h					flame retardant	(121)
PHU–MWCNT hybrid	tin	60 °C, 12 h + 90 °C, 4 h	HB			0ISO	50e	(122)
nanocomposite PHU hybrid	mild steel/Al	70 °C, 30 min + 135 °C, 1 h	4H	>2002	ac., alk., boiling H2O	5B	70.8d, 500 hv, 120 hw	(123)
nanocomposite PHU hybrid	steel	rt, 24 h + 100 °C, 2 h					55 daysv,w	(124)
nanocomposite PHU hybrid	glass	90 °C, 72 h under vacuum	3B–2HPe				UV-weather resistant	(125, 126)
PHU–sol–gel hybrid	glass	60 °C, 24 h				7c	alk.t, ac.t, NaClt	(59)
	stainless steel					1.4c
	Ti6Al4V					0.7c
PHU–sol–gel hybrid	Ti6Al4V	60 °C, 24 h				2.2x,c, 3.0y,c	Hank’s solutiont	(134)
	stainless steel					3.3x,c, 4.0y,c
PHU–sol–gel hybrid	Al	rt, 24 h + 80 °C, 12 h + 120 °C, 2 h	202Pe	>200		2.95c	82°k	(108)

^aMEK rub test.

^bAlso resistant to xylene.

^cPull-off test, MPa.

^dImpact resistance, lbs in.

^eImpact resistance, cm/kg.

^fAbrasion resistance, in cycles.

^gIron phosphate pretreated.

^hAfter 24 h, immersed in deionized water.

ⁱMandrel flexibility (1/8 in.);

^jGloss, 60°.

^kContact angle of water.

^lContact angle of iodomethane.

^mNo rust immersed in 10% NaCl solution.

ⁿAntibacterial activity against.

^oCrosscut adhesion performed on steel. Kept performance after washing in hot water.

^pMeasured on glass.

^q12 ft/min, 0.70 J/cm².

^rSaline solution.

^sRetained 85% of gloss after 200 double strokes.

^tAnticorrosion properties.

^uAgainst xylene.

^vNaCl salt-spray test at 35 °C.

^wEIS test in 5% NaCl.

^xLaser treatment.

^yOxygen plasma treated.

^zAntibacterial activity against Methicillin-resistant S. aureus, P. aeruginosa, and C. albicans without toxicity.

^aaac. acidic solution; alk. alkali solution; aro. fuel aromatic fuel; ASTM according to the ASTM D 3359 scale 0B worst–5B best; DEET N,N-diethyl-m-toluamide; DMF dimethyl formamide; eth. petroleum ether; Hank’s solution: physiological pH solution including sodium, potassium, calcium, magnesium and chloride; hy. fl. hydraulic fluid; ISO ISO 2409 scale: 0 best–5 worst; Kö König pendulum hardness (s); lub. oil lubricating oil; MDF: medium density fiberboard; MWCNTs multiwalled carbon nanotubes; Pe pencil hardness; Pen pendulum hardness; ref reference; rt room temperature; Sh Shore A hardness; Ti₆Al₄V titanium alloy; to. toluene; xy. xylene, Young Young’s modulus in MPa.