preferred sugar alcohol plasticizers confer styles that can be
reshaped at will.
Reshaping can also be achieved by applying a fixative that
can be molded when hot but sets when cold. For example
N-propionylethyleneimine/dimethylsiloxane copolymer applied to the hair allows the hair to conform to a desired style
that can be re-shaped by heating the hair to about 50°C with
a hair dryer.
26 Moreover, this polymer provides good feel
characteristics to the styled hair.
Frizzy hair can be controlled by polyamides that are made
from dimer acids, alkyldiamines and polyether diamines.
Latex Reemerges in New Forms
Latex polymers based upon ethyl acrylate and methacrylic
acid are well-known thickeners. When copolymerized with
other alkyl(meth)acrylates, the polymers are useful hair
fixatives. In an extension of this technology, Dow Chemical
researchers have found that inclusion of styrene as a co-monomer raises the refractive index and confers shine to the
hair, and the inclusion of hydroxyethyl methacrylate enhances the polymer solubility, giving rise to clear fixative solutions
that enhance the shine even more.
29 In another variant on
this theme, detangling with good removal from the hair is attributed to comb copolymers prepared from methacrylic acid,
ethyl acrylate and a macromer having a chain comprising
polyoxyethylene and polyoxypropylene.
30 Similar polymers
with hydrophobic main chains (for example by including styrene in the monomer mix) function as thickeners for aqueous
Another multifunctional thickening latex polymer, with
thickening and film-forming properties, is polyacrylate-1
crosspolymer. Commercial variants of polyacrylate-1 contain di-methylaminoethylmethacrylate (DMEAMA) as a co-monomer.
However, dimethylaminoethyl methacrylate is unstable in aqueous formulations due to hydrolysis of the DMEAMA, which is
initiated by“backbiting” of the lone pair on the nitrogen on the
electron deficient carbonyl group.
The hydrolytic character of these polymers is reported to be
improved by the use of dimethylaminopropyl methacrylate and
substantially improved by the use dimethylaminodimethylpro-pylmethacrylate.
32 These monomers resist the backbiting hydrolysis because they are less likely to form the cyclic intermediate.
Polymers with the latter monomer show good long term stability
with respect to viscosity, yield stress and turbidity.
Polymers in latex form offer the advantages of high solids ingredients in water as carrier. However, the aqueous phase must
be preserved. This aspect is a negative quality in a European
market that is driving toward “preservative-free” products.
Preservative-free lattices can be produced by drying the latex but
that leads to an undesirable dustiness. One way to overcome this
drawback is to prepare the polymer as beads by suspension polymerization rather than emulsion polymerization. However, it is
difficult to remove residual monomer from beads obtained from
the polymerization of methacrylic acid, ethyl acrylate and n-butyl
DSM researchers have discovered that removal of residual
monomer is facilitated by including ethyl methacrylate as a
monomer in the polymerization mixture.
33, 34 The result is a polymer produced as non-dusty beads with low residual monomer
content. The polymer (with an INCI name of acrylates copolymer and a tradename of Tilamar Fix A1000 from DSM Nutritional
Products) is soluble in water and ethanol when neutralized with
2-amino-2-methylpropanol and it confers excellent curl retention even at 90% relative humidity.
Mousse continues to be a viable product category and Kao
researchers have, interestingly, described foams comprising any
cationic polymer and any aqueous thickening polymer in combination with volatile and non-volatile silicones and fixative
polymers give good foam, good cracking sound when the foam
collapses and good hold properties on the hair.
From Lips to Hair
In cosmetic formulation it is not uncommon for innovation to
occur by transferring an ingredient from one product category