Cotton is known to be the most common fiber used
in many applications such as clothing, upholstery,
bedding, and curtains. However, it is also a highly
combustible fiber. Flame retardant finishing of cotton
fabrics and garments becomes necessary to improve
human safety under many circumstances.1 Many
flame retarding agents are halogen-based, which are
harmful to the environment and also toxic in nature
because these halogen compounds impart flame
retardancy by a vapor phase mechanism of free radical
scavenging with toxic gases being evolved in the
process.2 In an attempt to avoid generation of the
toxic and corrosive halogenated gases, the trend is
toward halogen-free, phosphorus-based compounds
as the flame retarding agents for cotton.3–5 Phosphorus-based
compounds act as flame retarding agents
in a condensed phase by increasing char formation;
hence there is hardly any chance for evolution of
toxic gases during combustion.6
Many techniques have been developed for
imparting flame retardant properties to cotton fabrics
including pad-dry-cure,7 chemical modification,8
ionized radiation graft polymerization,9 and
plasma induced graft polymerization.10 However,
there are some disadvantages to these methods due
to their deleterious effects on bulk properties of the
fiber such as lower tensile strength and moisture
regain, and fabric stiffness. Formation of an ultrathin
phosphorus-containing polymer film on the
fiber surface with the use of a suitable surfactant
can overcome these limitations. However, the uses
of surfactant-based methods, like admicellar polymerization,
to improve the flame retardant properties
of cotton fabric, have not been examined in the
literatures.
Admicellar polymerization is a method that can be
used to form an ultrathin polymer film on a substrate
surface.11 There are three basic steps to admicellar
polymerization as shown in Figure 1: admicelle
formation, adsolubilization of the monomer
into the admicelle, and admicellar polymerization to
form a thin polymer film on the substrate surface.
After the polymerization is complete, an additional
step, step four, is used to remove the outer-layer surfactant
by washing with water, to leave the polymer
film exposed on the substrate surface.
Admicellar polymerization has been successfully
used to coat thin polymer films on various kinds of