Photochemical reaction of Photopolymer pdf
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Photochemical reaction of
Photopolymer
Students:
Thu Tran
Loi Nguyen
Tuyen Duong
Truong Duong
Teacher:
Hoan Vu Tran
Outline
Introduction
Trung hop quang .(photopolymerization)
Photochemical reaction of photopolymer
Free radial
Cationic
Photocrosslinking
Photodegradation
Ung dung
Summary
Reference
Introduction
A photopolymer is a
polymer that changes its
properties when
exposed to light, often in
the ultraviolet frequency
of the electromagnetic
spectrum.
Introduction
Photochemical reaction of
photopolymer
Free Radial
Free radial
Photoinitiator
Direct
Photoinitiator
In-direct
Photoinitiator
Norrish I Norrish II Electron transfer
Hydrogen
abstraction
Direct Photoinitiator
Norrish I
Direct Photoinitiator
Norrish II
Electron transfer:
In-direct Photoinitiator
Hydrogen abstraction
Cationic
Onium:
Cationic
Aryl diazonium salts:
Cationic
Diaryl Iodonium
Ex:
Cationic
Photocrosslinking
•
Be bonds that link one polymer chain to another.
•
Can be formed by chemical reactions that are initiated
by radiation.
•
Change physical properties of photopolymers.
Photocrosslinking
Crosslinking by dichromate
Photodegradation
Be degradation of a photodegradable molecule caused by the
absorption of photons (light).
Ex: photodegradation of diazonium salt
NH
N
2
Cl
O
H
NH
N
2
X
*
*
n=2-3
NH
X
*
*
n=2-3
hv
Photodegradation
Ar
N
3
hv
Ar
N
Ex:Photodegradation of aryl azid group
O
N
2
O
3
S R
hv
O
O
3
S R
N
2
O
3
S R
H O
2
O
O
3
S R
COOH
H O
2
Ex: Photodegradation of o-Naphthoquinone diazide
Problem
O
-
O
2
hv
Problem
hv
Summary
Property Radical Cationic
Reaction rate high Moderate/high
Initiator by light Light and heat
Volume change large negligible
adhesion Moderate/good good
Comparision between free radical and cationic
polymerization
Reference
Polyme chuc nang va vat lieu lai cau truc nano book of
Nguyen Duc Nghia.
Photoinititor for free radical and cationic
polymerization by K.Dietliker.
The potential of cationic photopolymerization’ long
lived active center of Beth Ann Ficek in Univerity of
Iowa.
