Nonlinear optically active copolymers

Details Nonlinear optically active copolymers Nonlinear optically active copolymers

1999-08-17

2001-05-08

Hampton-Hightower, P. (Department: 1711)

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

Synthetic resins

From carboxylic acid or derivative thereof

C528S360000, C528S363000, C528S362000, C528S373000, C528S377000, C526S256000, C526S258000, C526S286000, C526S297000, C526S298000, C526S299000, C525S376000, C525S377000

Reexamination Certificate

active

06228977

ABSTRACT:

BACKGROUND OF THE INVENTION
Field of the Invention
The invention concerns nonlinear optically active copolymers and also electro-optical and photonic components including such copolymers.
Polymers with nonlinear optical properties (NLO polymers) are known to the art. Such materials are employed, for example, as electro-optical switches and are used in applications in areas of data processing and integrated optics, such as optical chip-to-chip connections, waveguiding in electro-optical layers, the Mach Zehnder interferometer and optical signal processing in sensorics.
An overview of current problems associated with the development of materials with pronounced nonlinear optical properties has appeared in “Angewandte Chemie”, Vol. 107 (1995), pp. 167 to 187. In addition to the requirements which must be met by the chromophores with nonlinear optical properties, problems are also pointed out which arise in the development of polymeric matrices for embedding the chromophores and the stable alignment of their orientation.
In order for polymers provided with covalently bound or dissolved nonlinear optical chromophores to become nonlinearly optically active and to possess a high 2nd order susceptibility, the chromophores must be oriented in the electric field (cf. J. D. Swalen et al. in J. Messier, F. Kajzar, P. Prasad “Organic Molecules for Nonlinear Optics and Photonics”, Kluwer Academic Publishers, Dordrecht, 1991, pp. 433 to 445). Orientation normally proceeds in the region of the glass transition temperature, where the mobility of the polymer chain segments enables orientation of the nonlinear optical chromophores to take place. The orientation achieved in the field is then frozen by cooling or better by cross-linking the polymer.
The 2nd order susceptibility &khgr;
(2)
thereby attainable is proportional to the space density of the hyperpolarizability &bgr;, to the ground state dipole moment &mgr;
0
of the chromophores, to the electric polarization field and to parameters which describe the orientation distribution after the polarization process (cf. K. D. Singer et al. in P. N. Prasad, D. R. Ulrich “Nonlinear Optical and Electroactive Polymers”, Plenum Press, New York, 1988, pp. 189 to 204).
Compounds with both a high dipole moment and high &bgr; values are of great interest. For this reason investigations have been made especially of chromophores which consist of conjugated &pgr;-electron systems which carry an electron donor at one end of the molecule and an electron acceptor at the other and which are covalently bound to a polymer, for example to polymethyl methacrylate (U.S. Pat. No. 4,915,491), polyurethane (European Patent Application EP 0 350 112) or polysiloxane (U.S. Pat. No. 4,796,976).
Known polymeric materials with nonlinear optical properties have the disadvantage, however, that relaxation of the oriented chromophore constituents takes place with the resulting loss of the nonlinear optical activity. This relaxation effect currently prevents the preparation of technically useful electro-optical components possessing long-term stability.
A further disadvantage of known polymeric materials with nonlinear optical properties is that it is not possible to modify the value of the NLO coefficient and other important parameters such as refractive index and glass transition temperature. As a result of their chemical structure, the chromophoric systems previously described also possess insufficient thermal stability to withstand without damage the thermal stresses arising during the fabrication and/or use of the electro-optical and photonic components. Thus a significant decrease in the measured electro-optical coefficients already takes place at a temperature of 85° C. as a result of the relaxation process of the chromophores in the polymer matrix. Stability of the optical coefficients at temperatures above 100° C. is actually desirable and for this reason a significantly higher glass transition temperature is needed for the polymeric material.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide nonlinear optically active polymer materials overcoming the above disadvantages and with stable nonlinear optical activity. It is a particular object to provide nonlinear optically active polymer materials in which relaxation of the chromophores is prevented up to temperatures above 100° C. and whose chromophore substituents are stable to thermal oxidation for long periods at temperatures above 200° C.
With this and other objects in view there is provided in accordance with the invention a nonlinear optically active copolymer comprising a polyadduct of
(a) at least one organic cyanate having at least two cyanate groups linked to an organic group which can be aliphatic or aromatic, and
(b) a nonlinear optically active compound with the following structure:
 in which
n=2 to 6,
R
6
, R
7
, and R
8
are independently of one another an H atom, a straight-chain or branched-chain C
1
- to C
20
-alkyl residue which can be interrupted by 1 to 5 ether oxygen groups, or a phenyl, naphthyl, thienyl, thiazolyl or pyridyl residue,
D=O, S or NR
9
, whereby R
9
is a hydrogen atom, a straight-chain or branched-chain C
1
- to C
20
-alkyl residue which can be interrupted by 1 to 5 ether oxygen groups, a benzyl residue or a phenyl or naphthyl residue,
L=O, COO or OCO,
E=OH, NH
2
, OCN or a residue with the structure
 i.e. a glycidyl residue bearing the group G,
with G=O, OCO (O at CH
2
) or NR
10
, whereby R
10
is an H atom or a straight-chain C
1
- to C
6
-alkyl residue,
Z is an electron-acceptor substituted methylene or imino group,
X is S, O, NR
11
or a ring double bond or
 wherein R
11
is a hydrogen atom, a straight-chain or branched-chain C
1
- to C
20
-alkyl residue or a phenyl or naphthyl residue and T is CH or N or Z and T together form a structure of type ═N—SO
2
—C≡, ═N—CS—C≡ or ═N—CO—C≡, and
Q is a CH— or CR
12
-group or N, whereby R
12
is a straight-chain or branched-chain C
1
- to C
20
-alkyl residue or a phenyl or naphthyl residue.
In accordance with a particular feature of the invention, the organic cyanate has the following structure:
in which
R
1
, R
2
, R
3
, R
4
=H, halogen, C
1
- to C
10
-alkyl, C
3
- to C
6
-cycloalkyl, C
1
- to C
10
-alkoxy or phenyl, whereby the alkyl and phenyl groups can be fully or partly fluorinated;
in which
M is a chemical bond, O, S, SO, CF
2
, CH
2
, CH(CH
3
), C(CH
3
)
2
,
C(CF
3
)
2
, N═N, CH═CH, COO, CH═N, CH═N—N═CH, alkylenoxyalkylene with a C
1
- to C
8
-alkylene residue or a residue with the structure
 wherein R
1
, R
2
, R
3
and R
4
have the meaning given above;
in which
r=0 to 20,
R
5
=H or C
1
- to C
5
-alkyl; or
(4) NC—O—(CF
2
)
p
—O—CN wherein p is an integer from 4 to 12.
In preferred embodiments of the nonlinear optically active copolymer of the invention, each of the substituents R
1
to R
5
represent a hydrogen atom. The residue Z is preferably a dicyanomethylene, alkoxycarbonylcyanomethylene, cyanimino or alkoxycarbonylimino group. The group Y preferably represents CH and the group X preferably represents a 1,2-annellated benzene ring.
Improved properties of the NLO materials provided by the invention include a high level of NLO activity and thermal stability which can be exploited for the fabrication of electro-optical and photonic components. Thus the copolymers according to the invention eliminate the problems associated with the materials of the prior art, which have a lower NLO activity and a lower glass transition temperature, so that the NLO effect is inadequate for the above applications and the anisotropic properties are subject to a too rapid relaxation.
The di- and polycyanate reactants used according to the invention, and their prepolymers, are known per se from adhesive and lamination technology. Dicyanates of perfluorinated dihydroxyalkanes with 4 to 12 C atoms have also proved to be especially suitable.
Following are representative organic cyanate

Affiliated with

Also associated with

Rating

Nonlinear optically active copolymers does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Nonlinear optically active copolymers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nonlinear optically active copolymers will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2443197