A recently invented n
ovel family
of RAFT (Reversible Additi
on-Fragmentati
on chain Transfer) agents having a c
omm
on f
ormula Z–C(S)–S–CR
2COOR
1 where Z = –SR, –NR
2,
or –OR, and R
1 represents H
or a variety
of functi
onal gr
oups all
ows f
or tail
oring their hydr
ophilicity–hydr
oph
obicity balance. A limited hydr
ophilicity
of the RAFT agents can be achieved which is sufficient f
or their diffusi
on thr
ough water, yet the agents are hydr
oph
obic en
ough t
o phase-separate
out
of water. Thus, the limited hydr
ophilicity
of
otherwise hydr
oph
obic agents all
ows them t
o be at the l
oci
of p
olymerizati
on making them suitable f
or the emulsi
on p
olymerizati
on mechanism. With several RAFT agents, g
ood c
ontr
ol
over m
olecular weight was dem
onstrated f
or a br
oad variety
of ab initi
o acrylic emulsi
on p
olymers. F
or methyl methacrylate, a p
orti
on
of RAFT did n
ot engage, resulting in less than the the
oretical number
of p
olymer chains. It was f
ound, h
owever, that as little as 10 wt %
of an acrylic m
on
omer sl
owed d
own p
olymerizati
on en
ough t
o engage all RAFT agent m
olecules and yield predicted m
olecular weights. A br
oad variety
of c
ol
orless and
od
orless telechelic acrylic and methacrylic emulsi
on p
olymers were synthesized.
Microemulsion and solution-dispersion techniques produced clean colloidally stable RAFT dispersions. These two techniques did not require RAFT agents with tailored hydrophilicity–hydrophobicity.
The UV spectra and photooxidative stability of the RAFT polymers were studied. The RAFT fragment in polymers appeared to have no impact on their photooxidative stability.