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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.

[email protected]

Effective 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