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Polymer Chemistry 2018
Polymer Sciences
ISSN: 2471-9935
Page 55
March 26-28, 2018
Vienna, Austria
3
rd
Edition of International Conference and Exhibition on
Polymer Chemistry
P
hoto-triggered adhesion is one of important technologies in
efficient manufacture of products such as home appliances
and electronic components. These products will be dismantled
into their parts after use, for reusing and recycling. Today,
adhesive materials are required to satisfy both strong adhesive
strength and dismantling ability. In my presentation, a thermally
dismantlable photo-adhesive system has been proposed. This
system utilizes two key reactions, i.e.
base proliferation reaction
and
disulfide-disulfide exchange reaction.
The former is for
effective anionic UV curing, or photo-adhesion, and the latter is
for thermally dismantlement of adhered parts.
Base proliferation
reaction,
proposed by Prof. K. Arimitsu (
K Arimitsu, M Miyamoto,
K Ichimura (2000) Applications of a nonlinear organic reaction of
carbamates to proliferate aliphatic amines Angew. Chem. Int. Ed.
39(19): 3425-3428.),
is a base-catalysed autocatalytic reaction of
chemical compounds named base amplifiers (BAs), to enhance
photo-sensitivities of materials for photo-patterning and anionic
UV curing with photobase generators (PBGs). Using BA with
PBG, photo-triggered
base proliferation reactions
are progressed
to generate more basic species than from only PBG, under the
same UV irradiation condition. Photo-adhesion is effectively
realized by using BAs, because the adhesive strength is based on
formation of rigid cross-linked networks resulting from reactions
of resins with bases from BAs. In our case, both hard films and
adhesion samples were successfully fabricated with a PBG, a bi-
functional BA, and a bi-functional epoxy resin, after UV irradiation
at a wavelength of 365 nm (5000, 10000, or 20000 mJ cm
-2
) and
subsequent postbaking at 160
o
C for 10 or 30 min. In the adhesion
process, photo-triggered
base proliferation reactions
between
PBGs and BAs are caused, followed by addition reactions
between generated diamines and epoxy resins. On the other
hand,
disulfide-disulfide exchange reaction
is one of equilibrium
reactions. This reaction proceeds between two disulfide bonds
via radical or ionic process under relative mild conditions, even at
room temperature. Disulfide bonds have been integrated into self-
healing materials of lower glass transition temperature (
T
g
). In
our case, both a diamine from BA and a bi-functional epoxy resin
have a disulfide bond in their chemical structures. The cross-
linked networks fabricated with them also have many disulfide
bonds, and it was found that the value of
T
g
was 63
o
C. Therefore,
the adhesive strength is kept at room temperature. However, the
strength became weak at 100
o
C (above
T
g
), due to the
disulfide-
disulfide exchange reactions
as well as thermal relaxation of
the cross-linked networks. When a shear force is added to the
cross-linked networks with gentle heating, a microscopic stress
is added to the disulfide bonds located in the part having high
internal stress. Then, these bonds would take their interchange
reactions for releasing the stress. This stress relaxation results in
separating two cured bulks.
Biography
Masahiro Furutani has completed his PhD in Engineering from The Univer-
sity of Tokyo in 2013. He is now a research associate of Pure and applied
chemistry inTokyo University of Science, working under Professor Koji Arim-
itsu in the area of UV curing systems of kinds of resins for the applications
of coatings and adhesives.
furutani@rs.tus.ac.jpEffective anionic UV curing for a thermally dismantlable
photoadhesive having disulfide bonds
Masahiro Furutani
Tokyo University of Science, Japan
Masahiro Furutani, Polym Sci, Volume 4
DOI: 10.4172/2471-9935-C1-008