Photochromic polymer

1. A photochromic polymer of formula I:

(PC-L-(RO) n —) z X  I

wherein:

Z is from 2 to 8;

PC are independently selected photochromic moieties;

L are independently selected from a bond and linkers;

R are independently selected polymer chains selected from the group consisting of C 2 to C 4 alkylene and C 1 to C 10 alkoxy substituted (C 2 to C 4 alkylene);

n is an integer from 1 to 50;

X is a hydrocarbon comprising from 1 to 20 carbon atoms or a hydrocarbon ether or polyether of 2, 3 or 4 hydrocarbon units each of 3 to 6 carbon atoms joined through ether linkages and together providing covalent bonds to from 2 to 8 (PC-L-(RO) n —) units; and

wherein the photochromic polymer does not comprise silicon.

2. A photochromic polymer according to claim 1 wherein X is a hydrocarbon of formula:

C m H 2m+2−z

wherein m is from 1 to 6 and Z is as defined in claim 1 .

3. A photochromic polymer according to claim 1 wherein X is selected from the group consisting of ethyl, propyl, butyl, pentyl, and hexyl wherein z is 2; or

X is selected from the group consisting of

wherein z is 3; or

X is selected from the group consisting of

wherein z is 4, 6 or 8.

4. A photochromic polymer according to claim 1 comprising a poly(alkylene oxide) polymer which is selected from poly(propylene oxide) and copolymers comprising propylene oxide and one or more of ethylene oxide and butylene oxide.

5. A photochromic polymer according to claim 1 , wherein (RO) n is selected from poly(propylene oxide), polybutylene oxide, block copolymers of poly(propylene oxide) and poly(butylene oxide), block copolymers of poly(ethylene oxide) and poly(propylene oxide), block copolymers of poly(ethylene oxide) and poly(butylene oxide) and block copolymers of poly(ethylene oxide), poly(propylene oxide) and poly(butylene oxide) wherein the total of the poly(propylene oxide) and poly(butylene oxide) blocks provides a molecular weight in the range of from 200 to 10,000.

6. A photochromic polymer of claim 1 wherein the photochromic polymer is of formula IIa, IIb or IIc:

PC 1 -L 1 -(R a O) n1 —X 1 —(OR b ) n2 -L 2 -PC 2   IIa

wherein X 1 is selected from the group consisting of ethyl, propyl, butyl, pentyl and hexyl;

wherein X 2 is of formula C m H 2m-1 (straight or branched chain) wherein m is from 1 to 6;

wherein X 3 is of formula C m H 2m-2 (straight or branched chain) wherein m is from 1 to 6;

PC 1 , PC 2 , PC 3 and PC 4 are defined as for PC;

L 1 , L 2 , L 3 and L 4 are as defined for L;

R a , R b , R c and R d are as defined for R;

and

n1, n2, n3 and n4 are from 1 to 20.

7. A photochromic polymer according to claim 6 of formula IIa wherein R a and R b are polypropylene and X is propylene.

8. A photochromic polymer according to claim 1 wherein L are selected from the group consisting of:

a bond;

wherein

Y is independently NR19, oxygen or sulphur,

R19 is hydrogen or C 1-10 alkyl,

p is an integer from 1 to 15,

r is an integer from 0 to 10, and

Q is C 1-10 alkyl, C 1-10 alkenyl or aryl optionally further substituted by C 1 to C 10 alkyl, or substituted heteroaryl.

9. A photochromic polymer according to claim 1 wherein the photochromic moieties are independently selected from the group consisting of naphthopyrans, spiropyrans and spirooxazines.

10. A photochromic polymer according to claim 1 wherein the photochromic moieties are independently selected from the moieties of formula IIIa to IIId:

wherein R1 and R2 independently represent hydrogen, C 1-10 alkyl, C 1-10 alkoxy, C 1-10 hydroxyalkoxy, C 1-10 alkoxy(C 1-10 )alkoxy, phenyl, C 1-10 alkoxyphenyl, halogen C 1-5 haloalkyl, C 1-5 alkylamino, C 1-5 dialkylamino, arylamino, diarylamino, aryl C 1-5 alkylamino, or a cyclic amino group;

R1a and R2a are hydrogen or together with R1 and R2 respectively may form a carbocyclic or heterocyclic ring of 5 or 6 constituent ring members and optionally up to two heteroatoms selected from oxygen, sulfur and —N(R19)- wherein R19 is selected from hydrogen and C 1-10 alkyl;

R3 represents hydrogen, C 1-10 alkyl, up to C 20 cycloalkyl, up to C 20 bicycloalkyl, C 2-10 alkenyl, C 1-10 alkoxy, C 1-10 hydroxyalkyl, C 1-10 alkoxy (C 1-10 ) alkyl, C 1-10 aminoalkyl, C 1-20 alkoxycarbonyl, carboxyl, halogen, aryloxycarbonyl, formyl, acetyl or aroyl;

R4 represents, phenyl, C 1-10 alkoxyphenyl, C 1-10 dialkoxyphenyl, C 1-10 alkylphenyl, C 1-10 dialkylphenyl or one of the groups specified for R3;

or R3 and R4 together form a cyclic structure of the type

R5, R6, R7, R8, R9, R10, R14, R15, R16 are as defined for R1 and R2; and

R11 represents a linear or branched C 1-10 alkyl, C 1-10 hydroxyalkyl, or a C 5-7 ring.

11. A photochromic polymer of formula I according to claim 1 wherein the photochromic moieties (PC) are independently selected from the group consisting of

(a) 1,3-dihydro-3,3-dimethyl-1-neopentyl-6′-(4″-N-ethyl,N-(hydroxylethyl)anilino)spiro[2H-indole-2,3′-3H-naphtho[1,2-b][1,4]oxazine;

(b) 3-(4′-methoxyphenyl),3-(4″-(hydroxyethoxy)phenyl)-6-morpholino-3H-naphtho[2,1-b]pyran;

(c) 3-(4′-methoxyphenyl),3-(4″-(hydroxyethoxy)phenyl)-6-morpholino-3H-naphtho[2,1-b]pyran;

(d) 1,3-dihydro-3,3-dimethyl-1-isobutyl-9′-hydroxy-sprio[2H-indole-2,3′-3H-naphtho[2,1-b][1,4]oxazine;

(e) 2-(4′-pyrrolidinophenyl)-2-phenyl-5-hydroxymethyl-6-anisyl-9-methoxy-2H-naphtho[1,2-b]pyran;

(f) 2,2-bis(4′-methoxyphenyl)-5-hydroxymethyl-6-methyl-2H-naphthol[1,2-b]pyran;

(g) (2-(4′-pyrrolidinophenyl)-2-phenyl-5-hydroxymethyl-6-anisyl-9-methoxy-2H-naphtho[1,2-b]pyran;

(h) 3-phenyl-3-(4′-(hydroxyethoxy)phenyl)-6-morpholino-3H-naphtho[2,1-b]pyran;

(i) 1,3-dihydro-3,3-dimethyl-1-neopentyl-9′-hydroxy-spiro[2H-indole-2,3′-3H-naphthol[2,1-b][1,4]oxazine]; and

(j) 2,2-Bis(4′-methoxyphenyl)-5-hydroxymethyl-6-methyl-2H-naphtho[1,2-b]pyran.

12. A photochromic polymer according to claim 1 wherein the polymer comprises a poly(C 2 to C 4 alkylene oxide) selected from poly(propylene oxide) and copolymers of propylene oxide with one or both of ethylene oxide and butylene oxide and having a molecular weight in the range of from 200 to 10,000.

13. A photochromic polymer according to claim 1 wherein the glass transition temperature is less than 25° C.

14. A photochromic polymeric composition comprising a photochromic polymer according to claim 1 and a host polymer.

15. A photochromic polymeric composition according to claim 14 which is free from polydialkylsiloxane polymer.

16. A photochromic lens comprising a photochromic polymeric composition according to claim 14 .

17. A photochromic polymer according to claim 6 , wherein X 2 is selected from:

18. A photochromic polymer according to claim 6 , wherein X 3 is: