Solvent Effect on Photoinitiator Reactivity in the Polymerization of 2-Hydroxyethyl Methacrylate

Table 1

Apparent first-order rate constants (𝑘_obs) for the polymerization of HEMA in water and organic solvents.

Solvent	Dielectric constant^a (25°C)	Viscosity^a (mPa·s)^−1	𝑘obs×10^4(s^−1)^b
			RF	CQ	ST
Water	78.5	1.000	5.05	4.04	2.98
Acetonitrile	37.5	2.898	3.71	3.02	2.10
Methanol	32.6	1.838	3.53	2.90	1.93
Ethanol	24.3	0.931	3.12	2.62	1.71
1-Propanol	20.1	0.514	—	2.45	1.56
1-Butanol	17.1	0.393	—	2.39	1.45

aCRC Handbook of Chemistry and Physics, 90th edition, CRC Press, Boca Raton, FL, 2010.
bThe values of rate constants are relative and depend on specific experimental conditions including light intensity.