Polymer having switchable tackiness

Details Polymer having switchable tackiness Polymer having switchable tackiness

2002-10-11

2004-08-10

Peng, Kuo-Liang (Department: 1712)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From silicon reactant having at least one...

C528S010000, C528S042000, C528S421000, C526S319000, C526S323000

Reexamination Certificate

active

06774199

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a novel side-chain liquid crystalline polymer having a temperature-dependent switchable tack property.
BACKGROUND OF THE INVENTION
Tackiness is the ability of the surface of a material to adhere instantaneously to the surface of another material when the two materials are brought into contact with each other under a light applied pressure.
The preparation of conventional adhesives has been relied mainly on macroscopic and bulk techniques, i.e., blending various polymers and additives. However, such materials are not suitable for forming engineered interfaces which require special properties at specific processing conditions. For example, adhesives used in semiconductor dicing or grinding process, or in some biomedical processes, require switchable tackiness, an adhesive property that changes reversibly with the change of temperature, pressure or pH within a narrow range. In order to obtain an adhesive having such switchable tackiness, the molecular structure of the adhesive has to be designed to confer specific surface and viscoelastic properties thereon.
A side-chain liquid crystalline polymer undergoes a dramatic change from a highly structured state to a disordered state at its isotropic transition temperature and such a change over a narrow temperature range results in an abrupt change in its viscoelastic properties. Further, the surface properties of such a polymer would also undergo a sharp change at around the transition temperature, when the side chain and main chain thereof have different physicochemical characteristics relevant to the surface energy, unlike a conventional adhesive polymer whose viscoelastic property changes gradually over a broad temperature range.
Accordingly, the present inventors have endeavored to develop an adhesive polymer having tack properties that change sharply at a narrow temperature range.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a side-chain liquid crystalline polymer which exhibits switchable tackiness at a narrow temperature range.
In accordance with one aspect of the present invention, there is provided a polymer of formula (I):
wherein,
R
1
is
R
2
is selected from the group consisting of —SO
2
—, —C(O)—, —CH(COOH)—, —C(COOH)
2
—, —C(S)— and —C(NH)—;
R
3
is —CH
2
— or —CF
2
—;
R
4
is H or F;
a is an integer ranging from 30 to 500;
b is an integer ranging from 1 to 3; and
c is an integer ranging from 3 to 20.


REFERENCES:
Tang et al., Journal of Mass Spectrometry, vol. 31, (1996), 926-936.

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