3  5,721,317  4  Measurement  of the  true  molecular  weight  of a  coupled  star  polymer  is not  as  straightforward  or as  easy  to  make  using  GPC.  This  is  because  the star  shaped  molecules  do not  separate  and elute  through  the  packed  GPC  columns  in the  same  manner  as do  the  linear  polymers  used  for the  cali- In  general,  any of  the  solvents  known  in the  prior  art to  be  useful  in the  preparation  of such  polymers  may  be used.  Suitable  solvents,  then,  including  straight---and  branched  chain  hydrocarbons  such  as  pentane,  hexane,  heptane,  octane  and the  like,  as  well as,  alkyl-substituted  derivatives  thereof;  cycloaliphatic  hydrocarbons  such  as  cyclopentane,  cyclohexane,  cycloheptane  and the  like,  as well  as  alkyl- Molecular  weights  of  linear  polymers  or  unassembled  linear  segments  of  polymers  such  as  mono-,  di-,  triblock,  etc., arms  of star  polymers  before  coupling  are  conveniently  measured  by Gel  Permeation  Chromatography  (GPC),  where  the GPC  system  has been  appropriately  calibrated.  For  polymers  of the  type  described  herein,  the  suitable  calibration  standards  are  narrow  molecular  weight  distribu› tion  polystyrene  polymers.  For  anionically  polymerized  linear  polymers,  the  polymer  is  essentially  monodisperse  and it  is  both  convenient  and  adequately  descriptive  to  report  the  "peak"  molecular  weight  of the  narrow  molecular  weight  distribution  observed.  The peak  molecular  weight  is  usually  the  molecular  weight  of the  main  species  shown  on the  chromatograph.  For  materials  to be  used  in the  columns  of  the GPC,  styrene-divinyl  benzene  gels  or  silica  gels  are  commonly  used and  are  excellent  materials.  Tetrahydrofuran  is an  excellent  solvent  for  polymers  of the  type  described  herein.  Ultraviolet  or  refractive  index  detectors  may be  used.  Hydrogenation  of at least  90%,  preferably  at  least  95%,  of  the  unsaturation  in the  low  molecular  weight  hydroxy  func- tional  polydiene  polymers  is  achieved  with  nickel  catalysts  as  described  in U.S.  Pat. Nos.  Re.  27,145  and  4,970,254  and  U.S. patent  application  Ser. No.  07n85715  which  are incor› porated  by  reference  herein.  The  preferred  nickel  catalyst  is  a  mixture  of  nickel  2-ethylhexanoate  and  triethylaluminum.  Conjugated  diolefins  which  may be  polymerized  anioni› cally  include  those  conjugated  diolefins  containing  from  about  4 to  about  24  carbon  atoms  such  as  1,3-butadiene,  isoprene,  piperylene,  methylpentadiene,  phenylbutadiene,  3,4-dimethyl- 1,3-hexadiene,  4,5-diethyl-1,3-octadiene  and  the like.  Isoprene  and  butadiene  are the  preferred  conjugated  diene  monomers  for use  in the  present  invention  because  of  their  low cost  and ready  availability.  The  conjugated  diole› fins  which  may  be used  in the  present  invention  include  isoprene  (2-methyl-1,3-butadiene),  2-ethyl-1,3-butadiene,  2-propyl-1,3-butadiene,  2-butyl-1,3-butadiene,  2-pentyl-1,  3-butadiene(2-amyl-1,3-butadiene),  2-hexyl-1,3-butadiene,  2-heptyl-1,3-butadien  2-octyl-1,3-butadiene,  2-nonyl-1,3- butadiene,  2-decyl-1,3-butadiene,2-dodecyl-1,3-butadiene,  2-tetradecyl-1,3-butadiene,  2-hexadecy  1-1,3-butadiene,  2-isoamyl-1,3-butadiene,  2-phenyl  -1,3-butadiene,  2-methyl-1,3-pentadiene,  2-methyl-1,3-hexadiene,  2-methyl-1,3-heptadiene,  2-methyl-1,3-octadiene,  2-methyl-6-methylene-2,7-octadiene  (myrcene),  2-methyl- 1,3-nonyldiene.  2-methyl-1,3-decyldiene,  and  2-methyl-1,3- dodecyldiene,  as  well  as the  2-ethyl,  2-propyl,  2-butyl,  2-pentyl,  2-hexyl,  2-heptyl,  2-octyl,  2-nonyl,  2-decyl,  2-dodecyl,  2-tetradecyl,  2-hexadecyl,  2-isoamyl  and  2-phenyl  versions  of all  of  these  dienes.  Also  included  are  1,3-butadiene,  piperylene,  4,5-diethyl- 1,3-octadiene  and the  like.  Di-substituted  conjugated  diolefins  which  may  be  used  include  2,3-dialkyl-substituted  conjugated  diolefins  such  as  2,3-dimethy  1-1,3-butadiene,  2,3-diethyl-1,3-pentadiene,  2,3-di  methyl-1,3-hexadiene,  2,3-diethyl-l,3  -heptadiene,  2.3-dimethyl-1,3-octadiene  and the  like  and  2,3-fl.uoro› substituted  conjugated  diolefins  such  as  2,3-clifl.uoro-1,3- butadiene,  2,3-difl.uoro-1,3-pentadiene,  2,3-difl.uoro-1,3- hexadiene,  2,3-difl.uoro-1,3-heptadiene,  2,3-fl.uoro-1,3- octadiene  and the  like.  Alkenyl  aromatic  hydrocarbons  which  may be  copolymerized  include  vinyl  aryl  compounds  such  as  styrene,  various  alkyl-substituted  styrenes,  alkoxy› substituted  styrenes,  vinyl  napthalene,  alkyl-substituted  vinyl  napthalenes  and the  like.  Anionic  polymerization  is  often  terminated  by  addition  of  water  to  remove  the  lithium  as  lithium  hydroxide  (LiOH)  or  by  addition  of an  alcohol  (ROH)  to  remove  the  lithium  as a  lithium  alk:oxide  (LiOR).  For  polymers  having  terminal  functional  groups,  the  living  polymer  chains  are  preferably  terminated  with  hydroxyl,  carboxyl,  phenol,  epoxy,  or  amine  groups  by  reaction  with  ethylene  oxide,  carbon  dioxide,  a  protected  hydroxystyrene  monomer,  ethylene  oxide  plus  epichlorohydrin,  or the  amine  compounds  listed  in U.S  Pat  No.  4,791,174,  respectively.  The  termination  step can  result  in  release  of fine  particles  of  lithium  bases  as  described  in  U.S.  Pat.  No.  5,166,277  which  is  incorporated  by  reference  herein.  The  lithium  bases  may  interfere  with  hydrogenation  of the  polymer  and  preferably  are  removed.  wherein  R is an  aliphatic,  cycloaliphatic,  aromatic  or  alkyl› substituted  aromatic  hydrocarbon  radical  having  from  1 to  about  20  carbon  atoms  and  n is an  integer  of 1 to  4.  The  termination  of  living  anionic  polymers  to  form  func› tional  end  groups  is  described  in U.S.  Pat. Nos.  4,417,029,  4,518,753,  and  4,753,991,  which  are  herein  incorporated  by  reference.  Of  particular  interest  for the  present  invention  are  terminal  hydroxyl  groups.  A  monool  has one  such  terminal  hydroxy  group  on only  one end  of the  polymer.  A diol  has  a  hydroxy  group  on each  end of  the  polymer.  Polyols  are  such  polymers  which  have  more  than two  hydroxy  groups.  Such  polymers  may  be  linear  polymers  with  internal  hydroxy  groups  in  addition  to the  terminal  hydroxy  groups  or they  may be  radial  or star  polymers  having  multiple  arms  of  polydiene  radiating  from  a  central  core  and  having  terminal  hydroxy  groups  thereon.  More  specifically,  the  polymers  of the  present  invention  are made  by the  anionic  polymerization  of  conjugated  diene  monomers  in a  hydrocarbon  solvent  at a  temperature  between  0°  and  100°  C.  using  an  alkyl  lithium  initiator.  In  general,  when  solution  anionic  techniques  are used,  conjugated  diolefin  polymers,  polydienes,  are  prepared  by  contacting  the  monomer  to be  polymerized  with  an  anionic  polymerization  initiator  such  as  group  IA  metals,  their  alkyls,  amides,  silanolates,  napthalides,  biphenyls  and  anthracenyl  derivatives.  It  is  preferred  to use  an  organo  alkali  metal  (  such  as  sodium  or  potassium)  compound  in a  suitable  solvent  at a  temperature  within  the range  from  about  -150°  C.  to  about  300°  C.,  preferably  at a  temperature  within  the range  from  about  0°  C. to  about  100°  C.  Particu› larly  effective  anionic  polymerization  initiators  are  organo  lithium  compounds  having  the  general  formula:  to  about  1,000,000.  Most  preferably,  the  polymer  is one  having  a  molecular  weight  of  from  about  3,000  to  about  200,000  because  this offers  the best  balance  between  cost,  ability  to use  the  mildest  curing  conditions  and  achieving  good  processing  behavior.  substituted  derivatives  thereof;  aromatic  and  alkyl› substituted  aromatic  hydrocarbons  such  as  benzene,  naphthalene,  toluene,  xylene  and the  like;  hydrogenated  aromatic  hydrocarbons  such  as  tetralin,  decalin  and the  like;  linear  and cyclic  ethers  such  as  methyl  ether,  methylethyl  ether,  diethyl  ether,  tetrahydrofuran  and the  like.  RLi,. 