Polymers

Details Polymers Polymers

1999-09-16

2001-05-01

Acquah, Samuel A. (Department: 1711)

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

Synthetic resins

Cellular products or processes of preparing a cellular...

C528S367000, C528S369000, C528S373000, C528S398000, C528S498000, C525S535000, C525S538000, C525S539000, C525S540000, C521S050000, C521S082000, C521S154000, C521S159000, C424S497000

Reexamination Certificate

active

06225367

ABSTRACT:

The present invention relates to novel biocompatible polymers, in particular copolymers of a perfluoroalkylpolyether macromer and a charged monomer, and products formed therefrom, for example membranes or optical devices and implants.
Perfluoroalkylpolyether (PFPE) polymers and ophthalmic applications thereof are known, for example, from PCT applications WO 96/31548, WO 97/35905 and WO 97/35906. The documents disclose the ability of PFPEs to support the cell growth and attachment of corneal epithelium cells both invivo and invitro. The polymer-tissue interface responsible for determining the level of protein deposition and cell growth support can be manipulated by plasma coating which can subsequently be attached with biological proteins such as collagen or polysaccharides such as dextran. However, this technique is essentially limited to surface modification but is unable to affect the internal surface area of the polymer, which is an important drawback especially in case of porous polymers. Therefore, events such as excessive protein or lipid deposition are difficult to control once they have diffused past the surface. The problem is magnified in the case of porous polymers by the large surface area to volume ratio that exists within the porous structure giving the protein or lipid etc. ample area onto which it can deposit.
It now has surprisingly been found that novel PFPE polymers with an improved wettability and cell growth ability and a considerably reduced tendency to accumulate protein or lipid deposits on the surface are obtained if a suitable PFPE macromer is copolymerized with one or more different charged monomers.
The present invention therefore in one aspect relates to a polymer comprising one or more perfluoroalkylpolyether units and one or more charged units selected from the group consisting of zwitter-ionic units and a mixture of anionic and cationic units.
It will be understood by those skilled in the art that the terms “perfluoroalkylpolyether unit” and “PFPE unit” mean preferably a moiety of formula
 —OCH
2
CF
2
O (CF
2
CF
2
O)
X
(CF
2
O)
y
CF
2
CH
2
O—  (1)
wherein the CF
2
CF
2
O and CF
2
O units may be randomly distributed or distributed as blocks throughout the chain and wherein x and y may be the same or different such that the molecular weight of the perfluorinated polyether is in the range of from 242 to 8000 and preferably from 242 to 4000. Preferably x in formula (1) is in the range of from 0 to 20, more preferably in the range from 8 to 12, and y is in the range from 0 to 25, more preferably in the range from 10 to 14. Even more preferred, x and y in formula (1) are both different from zero such that x is in the range of from 1 to 20, more preferably in the range from 8 to 12, and y is in the range from 1 to 25, more preferably in the range from 10 to 14.
Suitable charged units are, for example, a mixture of separate anionic and cationic units, or preferably zwitter-ionic units comprising one anionic and one cationic group each.
Suitable charged units correspond, for example, to formula
wherein either
(i) two of the three variables R
5
, R
6
and R
7
are hydrogen and the third one is hydrogen, carboxy, carboxymethyl or C
1
-C
4
-alkyl; or
(ii) R
5
and R
6
together with the adjacent carbon atoms form a 5- to 7-membered cycloaliphatic or heterocyclic ring and R
7
is hydrogen; or
(iii) R
5
and R
6
are each hydrogen and R
7
and A together with the adjacent carbon atoms form a 5- to 7-membered cycloaliphatic or heterocyclic ring; or
(iv) R
5
and R
7
are each hydrogen and R
6
and A together with the adjacent carbon atom form a 5- to 7-membered cycloaliphatic or heterocyclic ring;
A is a direct bond or a functional group, for example a carbonyl, carbonate, amide, ester, dicarboanhydride, dicarboimide, urea or urethane group; and
Z is an aliphatic, cycloaliphatic or heterocyclic moiety comprising an anionic group or a cationic group or one anionic and one cationic group each.
A group of preferred units of formula (2) corresponds to formula
wherein
A is a direct bond or an above-mentioned functional group, preferably a carbonyl, ester or amide functional group and more preferably an ester group —C(O)—O—.
A further group of suitable units of formula (2) corresponds to formula
wherein
q is an integer of 2 or preferably 1, and A and Z are as defined above.
Still a further group of suitable units of formula (2) corresponds to formula
wherein
R
8
is oxygen or preferably nitrogen and Z is as defined before.
Still a further group of suitable units of formula (2) corresponds to formula
wherein
R
8
and Z are as defined before.
Suitable anionic groups of the moiety Z are, for example, —COO
−
, —SO
3
−
, —OSO
3
−
, —OPO
3
H
−
, —OPO
2
−
OR
11
or bivalent —O—PO
2
−
—O—, wherein R
11
is, for example, C
1
-C
12
-alkyl, preferably C
2
-C
8
-alkyl and in particular C
3
-C
6
-alkyl; preferably a group —SO
3
−
, —OPO
2
−
OR
11
or a bivalent group —O—PO
2
−
—O—, wherein R
11
is as defined above; and in particular a group —SO
3
−
.
Suitable cationic groups of the moiety Z are for example a group —NRR′R″
+
or a bivalent group —NRR′
+
—, wherein R, R′ and R″ may be the same or different and are each independently of the other, for example, hydrogen or C
1
-C
24
-alkyl, preferably hydrogen or C
1
-C
4
-alkyl and most preferably each methyl or ethyl.
A group of preferred moieties Z are cationic ones wherein Z comprises one of the above-mentioned cationic groups. Another group of preferred moieties Z are anionic ones wherein Z comprises one of the above-mentioned anionic groups. Z is more preferably a zwitter-ionic moiety which comprises one of the above-mentioned anionic and cationic groups each.
The moiety Z is for example unfluorinated or fluorinated C
2
-C
30
-alkyl, preferably unfluorinated C
2
-C
12
-alkyl, and more preferably unfluorinated C
3
-C
8
-alkyl, which is in each case uninterrupted or interrupted by —O— and substituted and/or interrupted by one or two of the above-mentioned anionic and cationic groups. Z is preferably C
2
-C
12
-alkyl and even more preferably C
3
-C
8
-alkyl which is substituted and/or interrupted by one of the above-mentioned anionic and cationic groups each.
Z as a cycloaliphatic or heterocyclic moiety is, for example, a radical of formula
-[(alk)-(R
9
)
s
]
t
-R
10
  (3),
wherein (alk) is C
1
-C
12
-alkylene, preferably C
1
-C
4
-alkylene, s is 0 or 1, t is 0 or preferably 1, R
9
is for example —O— or —NH—, and R
10
is a 5- to 7-membered cycloaliphatic or heterocyclic ring, preferably a 5- or 6-membered heterocyclic ring, which is in each case substituted and/or interrupted by one or two of the above-mentioned anionic and cationic groups. Z is preferably a zwifter-ionic moiety of formula (3), wherein (alk) and t have the above-given meanings and R
9
is a heterocyclic 5- or 6-membered ring comprising a bivalent group —NRR′
+
— and one of the above mentioned anionic groups, preferably a carboxy group.
Preferred charged units of the invention are zwitter-ionic units of formula (2a),wherein A is a carbonyl, ester or amide group, Z is C
2
-C
12
-alkyl which is substituted by —NRR′R″
+
, —COO
−
, —SO
3
−
, —OSO
3
−
, —OPO
2
−
OR
11
or —OPO
3
H
−
and/or is interrupted by a group —NRR′
+
— or —O—PO
2
−
—O—, R, R′ and R″ are each independently of the other hydrogen or C
1
-C
12
-alkyl and R
11
is C
1
-C
12
-alkyl, with the proviso that Z contains one anionic and one cationic group each.
A preferred group of zwitter-ionic units corresponds to the above formula (2a), wherein -A-Z is a radical of formula
—C(O)O-alk-NRR′
+
-alk′-An
−
  (3a)
or
—C(O)O-alk-O—PO
2
−
—O-alk′-NRR′R″
+
  (3b),
wherein
R, R′ and R″ may be the same or different and are each independently of the other hydrogen or C
1
-C
12
-alkyl, preferably C
1
-C
4
-a

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