CA2102425A1

CA2102425A1 - Butadiene acrylonitrile polymeric coating and chromatographic packing material

Info

Publication number: CA2102425A1
Application number: CA 2102425
Authority: CA
Inventors: Ethan S. Simon; Kevin B. Holland; Christopher Mcclanahan
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-03-04
Filing date: 1992-03-04
Publication date: 1992-09-05
Also published as: WO1992015385A1

Abstract

A chromatographic packing material includes a coated support material which is a chromatographically suitable substrate. An immobilized butadiene acrylonitrile polymer coating is provided on the substrate. The copolymer can be crosslinked by gamma radiation, or by means of a crosslinking agent such as dicumyl peroxide. The support material can be silica, alumina, diatomaceous earth, zeolite, porous glass or carbon, but preferably is spherical lamellar shaped crystals of aluminum hydroxide. The aluminum hydroxide crystals are bonded together at a central core and extend radially outwardly from a central core with a particle density ranging from 0.3 to 2.5 g/cm3 and a diameter of 2 to 150 microns. The organic materials are separated by providing a bed of packing material selected from the group consisting of silica and alumina, diatomaceous earth, zeolite and porous glass with a polymeric coating being bonded thereto. Organic materials are introduced to the bed, and an eluting fluid is added. The fluid and one of the organic materials are removed from bed, and the materials are then separated and removed from the fluid. A chromatographic packing material is disclosed comprising a coated support material which is a chromatographically suitable substrate, with an uniform immobilized functionalized coating. A chromatographic column is disclosed having a stationary phase with a suitable substrate coated support material and an uniform immobilized functionalized coating. A
stationary phase for reversed-phase liquid chromatography consisting of a crosslinked, polybutadiene-coated, macroporous, alumina substrate is disclosed wherein the micropores have a diameter predominantely in the range of 50 to 1000 Angstroms, and the alumina substrate is so occludingly coated with polybutadiene that the integrity of the stationary phase is not adversely affected by extended exposure to liquid environments having a pH of 12. The method for preparing a stationary phase for liquid chromatography by occludingly coating onto a macroporous alumina substrate having micropores of a diameter predominantely in the range of 90 to 500 Angstroms, an unsaturated polybutadiene oligomer having pendant vinyl groups and a molecular weight less than 50,000 Daltons. The polybutadiene oligomer is partially crosslinked to the substrate to provide a polybutadiene coating having pendant vinyl groups. The hydrophobicity of the polybutadiene coating is increased by providing alkyl groups onto said polybutadiene coating, so that the retention time of o-xylene is increased by at least 30 % over retention time of a stationary phase coated with polybutadiene having 18 mole percent vinyl groups per butadiene unit.

Description

BU~ADIEN~ ~C~YL~IT~I~E PO~YMERIC CO~TING
~N~.CHROMATo~RAP~IC PA~XING ~ATERIAL
BA~KG~UN~ O~ ~H~ TNVX~IO~
el~ of the Invention In ong ~mbodl~s~t, this invention relates ~o the i~mobi-lization o~ h~droc rbonac~ous polymer~ on inorganic support ~aterial~ for~bsequent use as ch~oma~o~raphic sta~ionary ph~s~. More speciically,. this invention relate5 t~ the ~oatlns of a pol.ymer onto a ~etal oxide ~ollowed by in situ cro~slin~lng of ~he polymer thereby producing stationary phases ~hat exhibit unlque chromatographic sele~tivl~ies an~ excellent pH and chemi-c~l stability.
In a second embodiment the ~nvention relates to the ~obi-li~ation ~nd sub~equent ~unctionalization of a h~droca~bonaoeous polymer~ ~n lnorganic support materials ~or sub~equent use as chromatographic stationar~ phase~. More specifically, this inve~-tion relate~ ~o the coating of ~ polymer onto ~ me~al oxide fol-lowed by in s~tu cros~lin~ing o~ ~he polymer and chemical ~unctionalization thereby producing ~t~tionary phases that ex-hibit unique chromatographic selectivities and excellent pH and chemlcal s~ability.

~}~ .
Che~i~ally modified ~;lica supports are currently ~he most w~dely used sta~ionary phases for r~verged-pha6e liqu~ d chromat~g-r~phy. By reversed-phase chromato~rgphy it is meant that the ~d-so~bent is l~ss polar than th~ eluting s~lvent, and in normal phase ~hrom~tography ~he ~dsorbeht ~g more polar th~n the eluting ~olven~. That is, ln ~ver~ed-pha~e chro~atography, the more non-polar ~a~p~e ~omponent~ inte~Ac~ ~ore with the relatively non-polar ~tatlonary phase and thus elute later than pola~ ~ample components. ~pical mobile phas~ or reversed phased ~hromatog-raphy a~e aqueo~s buffers, water, ~ethanol, acetonitrile, tetrahydrofuran, and miXtUres of wa~er or buffer With these or-~allic s~l~rents.

- `WO ~ 8~ ~ 2 ~ 0 2 ~ P~/U592/01~2 f ~

~ However, these alkyl-bonded ~llica~based ~aterials suffer a from ~wo ~aj~r limitat~un~ t, ~e5~ua~ n~l gr~up5 ~re 3 quently have adver~ efect~ on chromatographic per~ormance, and 4 second, ~ilic~-ba~ad materlals a~ stablQ only over a pH range o~

2 ~ 8.5. In particular, of the var~ous commercially ~vallable 6 sllica-based st~tionary phase~, cyano bonded pha~e~ ar~ c~n 7 sidered ~o be thP leAs~ rugged. Polymeric support~ exhibit 8 enhanced p~ st.ability but ara oIten lltnl~ed by their lacX of 9 structural rigidity and low ef~iciencies due to the poor di~
lO ~uslonal properties of soluteY ln these materlals.
11 As a result of the a~orementio~ed di~iculties, attent~on 12 has been given to an approaoh that involves the deposit~on of a i3 hydrophobic, chemlcally stable polymer onto the surf~oe of an i~
14 organic carxier f~llowed by a radical-initlated cross-lin~ing reaction which serveç to lmmobilize a thin layer of polymer on 16 the surface o~ the support. ~h~s general approach ha~ been taken 17 by va~ious researchers (e.g. Schomburg, Regnier, etc.) but, to 18 date,~no ma~erial has been report~d which exhlblt~ the combina-19 tion of ~cid.and b~se stability, high e~iciency and good chrom~togr~phic selectivi~ies, aspaoially ~or macrocyclic an-21 tiobioti~ a~rocycl~c ant~bioti~s, su~h as ery~hromycin ~re 22 wldely u~ed and improved ~ethods for ~helr analysis ~nd sep~r~-2~ tion are hlghly desira~le for macrocycllc anti~iotics. Methods 24 for coatlng 1norganic suppor~s ~ith polymers to crea~e support6 for ~hromato~raphy are known. Schnecko and Bieber (SchnecXo, H.
. 26 and Bieber, O, ~ie_An~ewandte ~ackromolekulare Chemie 1571, 20, 27 lll-llg) describe co2ting Chromosorb P with polymers including 28 polybu~di~ne and hydroxy-termlnated polybutadi~nes and nitr~le ~9 r~ber, as well ~5 di~romo polybut~diene after amine treatme~t.
~h~e use of dlcumyl peroxide i8 ~isclo~ed a~ an agent ~or ~u~se-31 q~ently crosslinking the polymers t~ create stationary pha~e~ fo~
~2 gas chroma~ography. ~his disclosure in inapplicable to the in-33 st~nt i~vention be~ause of the dlffe~ences between gas and l~q~d 34 chromat~grap~y. For example, in modern high performance li~Uid cnromaeogr~plly ~L~1, pressures or several ~n~u~na ~ n- are - ~. ~ . - - , . .

.

`WO 92/15385 ~ 2 ~ 0 2 ~ 2 ~ ~ p~r/1J~92/01822 .
o~ten dev~loped with thf~ chromatogrl~phy oolumns. The hlgh pres 2 ~ure liguid wi~hin the column 6ub jects the b~se material to condi~

3 tions wll~ch are much more seYere, or ~bstantially differeht from 4 those experienced in gas chroma~ography. Unlike liqui~ chrom~tog-raphy, gas chromatography can not b~ applied to the s~paration of 6 ~olids, ~uch ~s prote~n~ and peptid~s, beca~se they can not be 7 ~ntrained ln the mo~ile gas phase.
B Schomburg et al. (Schomb~rg, G.; Xohler, J: Figye, H.;
9 Deege, A.: Bien~Vogel~an~, U., ~h~omatoaraphia 19~ 65-274) ~eport the ~mmobilization of polymers on particles of silica and 11 al~min~ using 60co irradiation to prepare statlonary phases ~or 12 liqui~ ch~omatography and describ~ ~urthc~ i~provements in sub~e-13 quent ~licatlons (including Bien-Vogelsang, U.; Deeg~, A.;
14 ~i~g~, ~,, Khler, J.: Schomb~rg, G., Chromatoqra~hla l~q, 1~, :
170-179, Figge, ~1.; Deege, A.; Kohler, J.; Schomburg, G. J.
~6 ~h~omat~ar~hv ~986, 351, 393-408; Kolla, P, Xohle~, ~. Schom~
17 burg, G. Chroma~oq~a~hia 1~87, 23, 465-472~.
lB . Ko~aXa ~t al. ~U.S. Pat~n~ ~,054,353, Aug. 30, 1977) l9 describe the r~diation-induced ~ro~slin~lng of monomers on ~he sur~ace of inorganic substra~es and simple chemical modi~icatioh 21 o so~ polymers, such as ~ul~onation oP ~tyrene. Berezkin et 22 al. (Berezkin, V.G.; Xolbanovskli, Yu. A,; XyaZimov, E.A. æh~
23 E~z._~him. 1~6~, ~0, 1921~ also ~e~crlbe modify~ng suppo~t6 by 24 dep~siting mono~ers and crosslinking by irradiation.
Z5 Re~n~er et al. in a series o~ publicatlons and ih a patent 26 (U.S~ ~at~nt 4,245,005, Jan. 13, l9Bl) describe the ad~rbtion of 27 coatings, such as amines, to ~norgani~ support~ and then the 28 crosslinking of the ~oatinqs ~y chemlcal ~an~ to create ~stion-29 ~ry phasec ~uitable for ion-exch~nge ch~omatography.
A di~advanta~e o~ the~e methodc is that they prod~ce ~ta~lon-31 ary phases WhiÇh exhlbi~ chroma~ograp~ic behavior diff~rent from 32 .~hat of commDnly-~ed, com~e~cially-avallable materials. ~here '3 is a great relu~ance among ~ho~e who practice chro~atography to 3~ use ~tationa~y pha~s tha~ exhi~lt unam~1iar ~Qhh~ior because i~ ~ne iarye exis~ln~ iwuy of J~ Wi~::U~ de-~elGp2~ ac~ c '~ G

.
' ,, ' ' ' ' . , '~ ~' .

- ,' 2~.02!~:2c3 g2/1~38~ PCr~USg2~gz2 .
1 of certain skation~ry ph~ses i5 not appli~able. Accordingly, it 2 wo~ld be very de~irable to h~ve ~ sta-tionary pha3e th~t exhiblt~
~ ~hromatographic behavior &i~il~r to commonly-used, com~ercially~
4 available materials, but w~ich also ~xhibits improved chemical and m~ha~ical stability to alle~iate the deficiencle6 of inor--6 ganic supports coated With o~gano~ilanes and of polymer~¢ sup-7 port~. The ~terials described hy ~his invent~n ~ay be shown to 8 exhibit excelleht ~tabillty under acldic and ba~ic csndition~, 9 high ef2icien~y and good chromatogr~phic ~elactl~ities especially for proteins a~d peptides.
11 ~yMMARy O~ VENTION
12- In accordance with the present i~vention, ahroma~ographic 13 stationary phases are provid~d ~hich consist o~ a thin laye~ o~
14 crossllnked polymer oh an inorga~ic support. These material~ a~e 1~ shown to ~vercome many of the disadvantages associated with che~i-16 cally bonded metal oxides and pol~meric material~. The co~-17 po~ites he~in des~ribed exhibit a high degree of pH and chemical 1~ stability while providing a surface che~istry that is ideally 19 suited ~or the separation o~ classes of compounds such as an-tibiotics and complex carbohydrates.
21 The p~ocess for prepari~q 6uch chromatographic stationary 22 pha~es c~n involve the i~ ~it~ chemlcal mod1ficAtion o~ the 2~ coated/cro~slinked polym~r in order to produce ~ ~ur~ace 2~ c~emistry that is ~ailore~ to ~ particular chromatograPhic separa-tion.
26 The chromatographic packing material includes n coated sup-27 port ~aterial~. The coated support material ~s a ch~omatographi-28 c~lly xuitable substrate, hav~g a uniform immo'oillz~d coating.
2~ The co~ting i5 a butadie~e n~ryl,onitrile copolymer. The pnc~ing 3Q material i~ preferably employed in reversed-phase chromatography.
31 Th~ ~opolymer is orosslink~d, pre~erably through gamma radia-32 ~ion, or th~o~gh the use of a photolni~la~or vr thermally. The 33 copolymer can contain a the~mal initiator, as ~or example dicumyl 3~ peroxide.
~i ,.

:, . , ,. ~ . - -:
,; 1, :~ , ,,, ~ ;.
.: , , ., . - ~: ' .

`WO 92/lS38~ 2 1 ~ 2 '~ 2 ~ ~; P~IUS9~/~X8~2 f.; S
, ~rh~3 ~upport matcrial can be 2~ny of the pa;~icles used for 2 this ~urpo~e, ~s well ~nown in thQ art, as for example, sllic~, 3 alumi~a, d~tomaceous earth, zaollte or porou~ gl~ss. ~he 4 pre~erred ~upport ~a~erial is al~minum hydroxide particles. The alumi~u~ ~ydroxide parti~les ~re pre~erably spherical lamellar 6 shaped c~ystals. The crystal~ are pre~e~ably bonded toge~er at 7 a central ~o~e an~ extend radially outwardl~ from a central core.
8 The parti~læ density can range ~rom 0,3 to Z.5 g/cm3, and the par-9 ticle ~iameter ca~ be in the range ~rom 2 to ~50 microns.
The ~opolymer can be derived from a l~quld copolymer which 11 ~ont~in~ p~nden~ reactlve groups an~ c~n b2 carboxyl ~erminated.
12 ~he carboxyl term~nated copolymers may be considered to be long 13 chaln dicarboxlyic aoids having functionalitias between about 1.
4 and 2.4. The ~opolymer can be derived from a l~quid copolymer whi~h is vinyl ~ermi~ated and have reactive acrylate vinyl 16 groups. Preferably the copolymer i6 predominantly butadiene, 1~ with the butadiene to acrylonitrile ra~io being on the order of 5 18 to 1. The ratio, ~owever ~an be from abo~t 1:1 to about 10:1.
19 Al~o in accordance Wlth the present invention, ~hromatographia stationary phases are provided ~hi~h con~ist of 21 . Sunctlonaliz~d thin layer of ~rossl~nked polymer on an inorganic 22 support, ~hese ~a~erials ~re shown to o~ercome many of the disad-23 vantag~s asso~iated w~th chem~cally bonded metal oxide~ a~d 24 polymeric materials. T~e ~omposites herein descr1bed exhibit a hi~h de~ree of pH and chemical stabili~y while provid~ ng a sur-26 ~ace chemistry ~hat is i~eally su~ed for the separation of 27 classes Or compounds suoh as proteins ~nd peptides.
28 ~he process for prepa~ing 6uch chromatograp~ic stationary 2~ phases involves the ~hemi~al modificat~on of a poly~er-~oated ~n-~0 or~ani~ support ln o~de~ to produce a sur~ace chemistry that $s 31 tailored to a particular chromatographic separatiOn.
32 The chromatographic packiny material is a ~oated chromaco-33 graphl~ally~suitab~e substrate~ and lm~obllized ~unctivnalized 3~ ~oating on said substrate, said coating being a polymer having 3~ ~erminal vinyl group. Prer~ra31y ~ne pa~r~lny u~d~ a~ ~
.

' 21~2~
.`WO,~/1538S ~ ~ PCI/lJ~2/0~2X

, 1 employed in reversed-phase chromatography. The poly~er can be 2 Putadiena or a'butadiane acrylonitrlle copvlym~r, or other 3 polymers, ~s well known in the A~t. The gr~e~ moieties or 4 mono~eri~ group~ can be octadecene or oct~he.
The support material can ~e a~y ~f the well k~own ~aterials 6 used for this p~rpose, as for examp~e, s~lic~, alumina, 7 diato~ac~ous earth, zeolite or porous glass. Pre~erably, the sup-~ port ma~erial.is alumin~m hydroxide particles, whioh are spheri-9 cal lamellar shaped crystals. Pr~f~ra~ly, ~he aluminum hydroxide cryst~1~ are bonded togathe~ at a central core and extend 11 rad~ally outwardly from a csntral ~ore. The pa~ticle density can 1~ range ~rom 0.3 to 2.5 and th~ particle diameter i~ ~rom ~bout 2 13 to ~50 ~icrons.
14 ~RI~F DEscRIyTlo~-~E ~E FIG~RES
FigurQ l ~hows chromato~rams obtained before and after ex-16, posUr~ to pH 10.5 mobile phase.
17 Figure 2 ~hows the separat.ion of 6everal ma~rolide an-18 t~biotics at pH ll.O.
19 . F~gure 3 shows the separa~ion of several peniclll~n an-tiblotics at pR 3Ø
SCRIPTION O~ T~_PR~F~R~E~ ~M~QDIM~N~S
22 The ohro~atographi~ stationary pha~es compri~e an inor~anic ~3 carrier onto ~ich has beeh coated and crossl~nked a layer of or-24 gan~c poIymer. The inorgan1~ carrier~ tha~ ~ay be used ln the pr~sent lnvention include, but are not-necessarilY l~mited to 26 ~ a, silica gel~, glass, carbon, bent~ni~e, hydroxyapatite, 27 zirconia, titan~a and alumina. ~h~ preferred carrier i~ alumina 28 having a known average pore size, known particl~ ~ize and known 29 æUr~ace area. It is preferred tha~ the alumina has an average pore size of 50 - l000 Angstr~ms, a surface area of 5 - 250 m2/g, 31 preferably 40-1~0 m2Jg, and a particle si~e of 3 - 25 micrcns.
32 The primary requlrement fo~ the 1norganic carriers is that they 33 be essentially water insoluble and have ~ufficien~ surfa~ area 3~ ~> 5 m~g) for the coating O~ 3 ~u~fi~lent amount of a su~icient . .

2~2~2:`j W ~ ~2J1~5 . ' ~ PCrJ~S~2~1g22 ~ ; 7 1 The polymaric coating may be appl~ed ~o ~he inorganic ~up--2 port by known,methods re~erred ~o above. The or~anic polymers 3 employed i~ th~ p~e~ent ihve~tion~include~ but are not neces-4 ~a~ily limited to poly~butadlen~), poly(bu~adiene-acrylonitrile) and oth~rs. ~he primary requirements for the polym~r~ ar~ that 6 they b~ easi1y solubilized to facili~at~ the coa~ing proce~s ~nd ~hat they po~se~s chemic~l fu~c~ionalitie6, ~uch a~ unsa~urntad 8 carbon-carbon bonds, whlch a}low croc~linking and the ~ub~equent 9 gra~ting of monomers to ~h~ polym~r. The prefesred polymerlc coat~
lo ing consists of crosslinked polybutadiene.
11 Further d~tail~ o~ carrier mat~ria~ ar~ Sound in the prior 12 ar~, ~s for examp~e U.S. Paten~ 4,786,62a, 4,822,593, and 13 4,045,353, and the di~closure6 of w~ich are incorporated her~ln 14 by ~Çe~ehC~ ox in th~ ~ook, "Packing and Stationary Pha~e~ in Ch~omatograph~c Technique~" edited by X. ~. U~ger ~Marcel De~ker, 16 1~0).
17 The organic polymars employed in the present invention ih-18 ~ clude, but are not neces~arily limited to the r~nge of Hycar Reac-lg tive ~ uid Pclymers available from B.F. Goodrich, Inc. (~.g.
Hyca~ 130~X40, Nycar 1300X43, e~o.). The pri~ary practical re-21 quirements ror the polyme~ are that th~y b~ easily solubilized 22 to-facilitate the coating pro~ess and that they posse~s chemical 23 ~unctionalities which allow crosslinking a~d/or ch~mical grarting 24 reaction~.
2S In order to produce the ~ta~ionary phases described here, a 26 solution i5 prepare~ containing typically s 50~ (w/w relati~e to 27 the ~eiyh~ ~f support being uged) of poly~er in a ~uitable 501-28 vent (e.g. tetrahydro~uran, ethyl ace~ate). To the ~olution is 29 ~lso added ~ny necessary radi~al initiator~ o~ stabilizers at a level of 0-13% w/w. I~org~ni~ ~a~rie~, s~ch as alum~a, is &dded 31 ~o the solution in a round~bo~tomed flaçX ~nd ~haken for several 32 minu~es. The solvent is then removed ~y evaporation at.reduced 33 pressure usin~ a rotary evaporator until the material is free-3~ ~lowing.

. : -- , .:: . - : .
.,, , ~ . :: ~. : ;: . . . :
. ,, - :.. . . .
:~ : . . , :

2~L~32~2~f . ~0 ~tl53~S ~ ~~ P~TIUS92/C18~
O

1 ~he poly~er-coa~d ~upport ls then ~ubjected to a ~ro~sl~nk-2 ~ng r~a~tion ~ng a fr~s r2d~c~1 initi~tor te.~. dicumyl 3 peroxide) at e7 evated temperatures or by use of gamma irradiation 4 ~rom a 60Co source. After crosslinki~g, the material~ are ~ypi-¢ally washed with 1~ gla~ial acetia in h~xans or ethyl ~ceta~e 6 followed by a wash wit~ hexAhe~ The washed m~terlal is then 7 ~ried and pa~ked into ~olumns. Specif~a de~ail6 Sor particular ~ stationary phases are included in 9 Typi~ally, a monomer and add~tive, if used, are coated onto a polymer-coated inorganic ~upport followed by ir~adiation using a 11 69Co ~ource wh~ch serves to graft the monomer onto the polymer lZ coating.
13 The monomers, suCh as l-oc~decene, preferably contain un-14 saturation ~nd do not contain chf3mical functio~alit1ee which ~
unstable in the pH range of 1-13. Th~ amount of monomer used ~s 16 5-50~ tw~w) relat~ve to the amount o~ suppo~t us~d. To creata a 17 reversed-phase statlonary ph~ suitable ~or the separation of 18 peptides snd prot~in~, the pre~erred monomer is 1-octadecene.
1~ ~he additives are free radical initiators ~uch as pero~ides 20 (B.g, dicumyl~peroxlde or benzoyl peroxide)~ or rree radi~al ~ta-21 bilizers (~ù~h as allyl methacryia~e or ~-allyl a~rylamide). The 22 amoun~ of adaitive used is 1-15~ ~W/W) relative to the am~unt ~
23. ~onomer u~ed.
24 The graft~ng process i~ pre~erably c~rrled oUt by mixing the ~ohomer, ad~l~ive and suppo~ ~or 5-15 min~te# in a solvent that 26 dissolv~s the monomer and nddit~vef and t~en by removing th~ s~l-27 vent by rot~ry evapo~ation at reduced pressure until the material 28 i~ a ~Rlatively frae-flowing powder. This ~tep aost- the support 2~ with ~e mono~er and additive.
The graf~ting xea~tion ~n ~e carrled out either at elevated 31 t~mperature-, or by using ga~ma-irradi~on either in t~e 32 presence of air or nitro~en. If i~radia~ion ~rom a 60~o source 33 is used, th~ total dose o~ radiation is pr~f~rably in the range 34 of lolO ~Rad.
..e !, , ' , .
, ~ ,' " " _ ' '' ' , .

: 2 1 0 2 ~ 2 .~
~, W<~ Y~tl5385 ~~^ P~/US92/~18~
. . 9 1 ~ollowing~he gra~tlng ~tep, the supports ~hould be w~hed 2 w~th ~ suita~le ~olvent, such as hexane, to remove unhound 3 monomer and ad~i~ives ~o that the materi~ ultable ~or 4 ohro~atographlc purpo~es, In the ca~e o~ polymer-coated alumina ~teriuls, ~ ~olution of 1~ glacial acetlc acid in hexane is ef-6 fectiY~ in ~emoving unbound matex~al and preventlng subsequent 7 leaching o~ ~bound ~aterial during chromatograPhy.
8 Example~ / below. Sp~cific details ~or th~ prap~ration ~ o~ material~ and their use in chromatography are gi~en in Ex-10 amples 8 - 14 below.

12 ~his example de~cribes a process or ~oat~ng o~ alumina with 13 poly~butadiene-~crylonitrile~ by irradiation.
14 Poly~bu~adi~ne-acrylonitrile) (25 g, ~ycar VTBNX ~1300X43), ~.F. Goodri~h ~o., Cleveland, OH) and d~cumyl peroxide t2.5 ~, 16 Polysciences, Inc., Warrington, PA) were di~solved in 500 mL of 17 ethyl acet~te. S~nication aided the disYolution o~ ~he polymer.
18 The slightly cloudy solution wa~ added ~o a 1-~ round-bottomed 19 flask cnntaining 2$0 g of alu~ina powder (8 ~icron UnisphereR
2~ alumina, ~iotage, Inc., Charlotte~ville, VA) and the suspeneion 21 was sha~en ~or 1~ min. ~emoval o~ ~olvent by rotary evaporation 22 at redu~ed pre~sur~ yielded a fr~e-10w~ng po~der.
23 The fla~k containlng he coated powder was pl~ced near a 24 60co array ~or 24 h. at a dosage rate of 2 x 105 Rad/h.
~ollowing irradiation, th~ ~ple Was wash~d with ~3 m~ o a 26 ~olution oS hexane containing 1% o~ ~cQtic acid per gra~ of 27 alumin~ and then w~th -3 mL o~ hexane per gram of alumina. ~he 28 product wa~ drled either at r~duced pres~ure t~ give a free-2~ flowinq powder which was used to ef~e~t a range of separations by 30 high-performance liquid chromato~r~phy as described ln Examples 3i 2-~.
3X The ethyl aceta~e of thls example can be ~eplaced by other 33 solvents, SUCh as tetrahydrofuran, methyl ethyl ketone, or 34 a~o~atic solvents~ as well Xnown tD those 5killed in the ~rt.

~.

~ . ~ . .. ~-, 2 1 0 ~ '~ 2 ~
~o 92~l538~ . PC~/US9~/0182~
i . . 1 U

1 In this example, the e~act total radiation d~s~ge ~ not 2 cr~tical. In~easing the tot~l t~ o~ irradi~tion ~p to 7 d~y 3 did no~ a~fect the ~ub~e~u~nt chromato~raphic perform~nce o~ the 4 product. Other 60Co sourc~ could also be used advanta~eousl~.
In this example, ~he solventS u~ed to wa~h the product can 6 be advantageously replace~ by othe~ solvent~, such ~s ethyl ? ~cetate, and other Golvents ~u~able ~or sol~bilizing 8 poly~utad~ene-aorYlonitrile) o~ dicu~yl peroxlde ~nd their 9 ,degradation produc~s.
It should be Unders~ood that additives other than dicumyl 11 peroxide or no additives may ~ added to ~fect the cro~slinking 12 step. ExampleQ 6 and 8 illustxate that this g~neralization is pos-13 sible.
14 Crosslihking can be achle~ed by mean~ other than irradia-tion, sUch as thermal o~ photochemical treatment. Example 5 il-16 lustrates the u~e of thermal ~o~linklng.

18 Chromatographic performance o the alumina-ba~ed cyano ~t~-19 tionary pha-e.
A 3.5 g quantity of poly(~utadiene-acrylonitrile)~coat~d 21 alumina p~epared as in Example 1 ~bove ~aQ packed into a 4.6 mm 22 i~d, x 2~0 mm stainless steel column Usin~ ~ethanol at a pressure 23 o~ ~000 psi. A test mi.xture consl~ting of theophylline, 24 p-nitroan~line, methyl benzoat~, phenetole, and o-xylene (1 mg~m~
each in 50~ aqueous ~cetonitr~le) wa~ prepared and injected onto 26 the ~ol~mn. The test ~ixture component~ were elutsd usinq a 27 mobile pha~ of 45~ water and sS~ acetonitrile at a flow rate o~
28 0.5 ~L/min. Th~ efficiency of the colu~n was ~ound to be 35,500 29 plate~meter wlth an o-x~lene ~tention o~ 13 . 5 minutes . ~he pH
o ~he wa~er portion o~ the moblle phase ~as rai~ed to 10.5 with 31 aqUeous am~onia and after operation at this pH for Z4 hours the 3~ ef~i~iency was ~ound to be 35,200 plates/meter and the o-xylene 33 retention 13.4 m~nutes, This represents ~1% loss o~ retent~n - : ", - . .

,; . , . : : .:: . .: :
: ; .

_ ~ W ~ 9~/153~5 ~' 2 1 ~ 2 ~ 2 ~ ~ . PC~IUs92/0~8~
~ . .
. ..
, ..
1 and efS~ciency. T~e~e chromatographl~ measure~ts sh~w' ng the 2 ~igh le~el of pe~or~ance of th~ rlal at high pH are shown in 3 Figure 1.

Th~ chromatographic performanc~ o~ the matRrl~l de~crlbed in 6 Example 2 is ~urther lllustrated in ~igure 2. ~h~ chromatogram 7 shows the separation of a mixture of macrollde an~iobiotioc a~d 8 was generated using a mobile phase of 80~ 0,02~ KH2P04 20%
~ acetonitrile, apparent pH 10.9 an~ a 10w rate ~f 1.2 mL/min.
ThR~samples chrom~tog~aphed ~re .indicated in the figu~e caption.
11 After operation for 72 ho~s at pH lO.g, the measured loss of 12 c~l~mn e~fiaiency was found to be less th~n 1~.
13 Example ~
14 The same ~olumn as was u ~d in Sxample 3 was used for the sepa~-tion of ~ set o~ penicillinc (Fig~re 3) using a ~obile phase o~
~, .
16 7~ .015-M phosphate buffer ~pH 3.0) ~nd 28~ acetonitrile. ~hus ~ the invent~o~ ~xhibits good ~ab~ y over ~ w~de pH range with 18 ~o~d eeparat~on e~icienoy.
19 Example S
This example desc~i~es a pro~ess ~or coating of alumin~ with 21 poly (butadiene-acrylonitrlle) by thermal treatment.
1 g of Hycar VTBNX ~1300X43) and 0.1 g of dicu~yl peroxide ~3 were dissolved in 30 ~L o~ ethyl acetate. The resultin7 solutlo~
2~ was added to 10 ~ of 8 micron Unisp~ere alumina in a loO-mL
2~ round-hottomed flask and ~he sugpension W8s shaken f~r 15 min.
26 ~emov~l of solvent by rotary e~apora~ion at reduced pressu~e 2~ yielded a f~ee flowing powder~
28 The powd~r was heate~ ln an atmosphere of nitrogen at 110C
Z9 for 30 min~te~ an ~hen at 140~C or 3 h. ~he reaction fl~sX WAS
allowed to cool ~o ro~m temperat~re under a positive pressure of 31 nitrogen and ~hen W~Shed an~ used to e~fect separations following 32 Examp~e ~. The retention ~i~e of o-xylene was }1 min. and the 3; ef~cien~y was 17.000 pl~te6/~eter. When the ~ame alumina w~s 3~ coated with polybutadiene ~he r~ten~ion t~e o~ o-~ylen~ was g.

min~ nnd the efXlc~ency was lz,~ p~a~es/~e~er.

: ~ .: ~ -. - -..: . :
., : ~ `:

;wOg2tl53g~ 21 ~2~2~ /US92/01~22 1 Example 6 2 ~he procedure described in Example 1 was car~led oUt, except 3 the reaatants were 0.5 g o~ poly (b~tadi~ne-acrylonitrile),0.5 g 4 o~ allyl methacrylate and 5 g of alum~na. ~he reten~ion ttme of o-xyl~ne was 14.1 min, and the Qffi~ienay ~a~ ~5,000 6 plate~jmeter. ~his exa~ple sho~ed that dicumyl peroxide may be 7 r~placed by other additivR~.
8 Example 7 g A ~olution o~ 2.5 g o~ poly(butadiene-a~rylonitrile), 0.25 g of dicu~yl peroxide and 0.25 g Or divinyl benzen~ in 175 mL of ethy1 acstate was ~haken ~ith 25 g o~ ~ micron alumina ~owder for 12 lO min. Following ~emoval of the ~olvent by ro~ary evaporatich 1~ at reduaed pressure, the matexial was irradi~ed usi~g a 60Co 14 ~ource at 1.65 X 10$ Rad/h for 24 hr. The material was ~ashed as follows:
16 ThP ~ampl.e was slurried in 200 mL of ethyl ace~ate ~nd soni-17 ~ated for 10 min. The solvent was removed by filtration using a 18 Bchuer unnel. This procedur~ was repeated and the material was 19 then wa~hed with 150 m~ of hexane. ~he ~aterial was packed ac-aording to Example 2. ~he retentiOn t~me of o-xylene ~as 16 min.
21 T~is Example 7 shows that the addition of othe~ cro~slin~ihg 22 agehts ca~ er th~ characteristics of the material ~y altering 23 retention t~mes.
24 Hy~ar is ~ reqis~Rred trademar~ o ~. F. GoodriCh for ~$- but~diene homopoiymers and butadiehe/acrylonitrile copolymers.
26 ~he iso~er con~ent is ~arg~ly ~is/tr~n~ w~th vinyl (1,2 addltlon 27 of but~di~ne) being 25.~ ~r less. They have reactive ~ro~ps in ~8 both ~m~nal po~i~lons of th~ pol~mer chain and may have addi-~9 tional reaCtiVe groUps pendent on the chain, Some do not contain ~30 s~ nt~ or other Unre~c~ve compon~nt~. The design~tor letter C

31 indicates a ca~oxyl ~ro~p, V indicates a vinyl group, A ~ndi-32 oates an amine gro~p, T indicates ~erminal rea~tive groups, B in-33 dicstes but~diene, N indicates Acrylonitrile and X indica~es the 3~ p~esenCe of psndent reac~lve groups. The CT series of car~oxy~

' : :: ~ . -~ . ' : ", :; , :

~ - Wt~ ~!115385 ~ 2 1 ~ 2 ~ 2 ~ PCrrus9~/ot8z2 ~r~ 1 3 1 ~erminate~ liqu~d pol~mer~ ma~ be con~idered long chaln dioarbox-2 lyic ac~ds hav~ng functionalit~ between 1.8 a~d 2.4. The typl-3 cal properties ar~. as follows:
Hycar polym~r 1300X8 CTBN 1300X13 acrylonitr~le ~ 18 26 6 co~tent Carboxyl content 7 ~cid nu~ber 29 32 EPHR .052 .057 8 Broo~ield Vi~cosity mPa.s or oP, 9 27 13S,000 570,~00 Solu~ility para~ter ba~ed.on molar ~ttraction constant~ 8~7 ~.14 11 Specific gravity 25/25C O.g48 ~960 12 Fuctlo~ality 1.~ 1.8 Molecular w~ight, Mn 3,600 3, 200 The HYCAR Yinyl te~mina~d ~V~) liquid polymexs ~ve reac-14 tive acryla~ ~inyl groups and can be r~acted in~o systems involv-ing cur~s by freQ radical me~hanism~. The reactive ~inyl group 16 i~ separ~te ~rom the cis/trans/vinyl Un5aturation contribute~ by 17 the polymerized butadiene of the poly~er bacXbon~

~ypical propertles for the ~ethac~ylated polyme~ is as follows:

20 Hyaar polyme~ 1300X43 VTB~X
21 ~crylonitril~ % 21.5 22 Acid num~er Max. 5 BrooX~i~ld Vi~coslty 425,000 23 mPa.~ or cP, 2?~
24 Speci~i~ graYlty .981 2s So1ubility ParametQr 9.091 ~9 3~ .
31 ' ;

: . .;, ~. . :
:: :, . .,,. , : - . - . ...
: :

2 1 ~ 2 !.~
- ~NO!~/1538~5 PCI/US92/018 t 4 2Thi5 example describes the attaohment of octadecene ~o 3 polybutadiene-~oated alumina ~y irrad~ation.
4 Octadecene (3.0 g) and allyl methacrylate (0.24 g) wexe dis-S solved in 50 mL of hexane. The olu~ion was ~dded to a 100 m~
6 ro~nd-botto~ed flas~ containing lo.0 g of alumina powder coated 7 with polybutadiRn~ (8 mlcron Un~sphereR-P3P, ~iotage, Inc., Char-8 lotte~ville, V~) and a magnetic stirrin~ bar. The ~olution was 9 sti~red for lS ~in and the solvent wa5 remo~ed by rot~ry~e~apora-tion at reduced pressure. The flas~ was evacuated, ref illed with ~1 nltrogen, and capped.
12 The flask containing the coated powder was placQd near a 13 Çco arr~y and r~cei~ed a to~al dosase of 1.6 x 107 ~ad during a 14 period of 3 days.
lS ~ollowing irr~diation, the ~ample was washed With lO~ mL of 16 a solution of h~xane containing l~ of acetic acid a~d then with 17 100 mL or hexane. ~he prod~ct was dried a~ reduced pressure to 18 give a powder,which ~as packed into colu~ns and used to effect l~ th~ chrom~togra~hic ep~rations descrlbed in ~xamples 2 and 3.

21 ~e5cription of chromatographic performance of the alumina-22 `~ased Cl8 stationary phase.
23 A 3,5 g quantity Or polybuta~lene-coated alumi~a prepared ~q 24 i~ Examp1e l above was pacXed ~nto a 4.6 mm i.d. x 250 mm stain-2S less steel column using me~hanol a~ a pressure o~ 6000 psi. A
2~ tect mixt.ure consis~ing of t~eophylli~e, p-~ltr~anil~ne, ~ethyl ~7 benzoate, phenetole, and o-xylene (l mg/~L each in S0~ aqueous 28 ace~onl~rile) was prep~red and inj~cted on~o the column. ~e 29 test miX~ure c~mponents were elu~ed ~Sing a ~obile phase of 45%

30 w~ter ~nd 5S% acetoni~r~le at a flow rate of 0.5 mL/min. ~he s~a-31 tionary phase was then su~ec~ed to alternate cycles of isocratic 3~ and q~adient eluti~n separ~tion~ for 72 hours us~ng tri-3~ f-ouracetic a~id (TFA)/wa~er/aaetontrile ~obile phases. ~his w~s 3~ foliowed by Washing Wl~h more than 100 column ~olumes each of ~%

.. ~ , . . ..

2102~
~ 0 92lt53~$ PCT~USg~/0l~22 1 TFA in 50/50 ~ater/acetonltrile and 0.1-M N~o~ in 50/50 2 water~ethanol, 'rhis treatment resulted ln loc~es of la~s than ~%
3 in both retenti~n and e~iciency. ~he data is shown ln Plgure 1.
4 - EX~MPL~ 10 S Ths chroma~ograph~c performance o~ th~ mater~l described in 6 Example 8 i~ further ~llustrated in ~igure~ 2 and 3. ~h~ co~di-7 tions ~or th~ s~par~tion are describrad in the fig~re oaptiDns. As 8 c~n be ~en f om the ~i~u~es, the chromat~qraphlc performance on '~ ~he invention compares qul~e ~vorably With that of a widely-used, c~mmerclally a~ailable silica-based ~olumn. The combina-11 tion o chromatographic per~'ormance and pH ~abili~y makes ~.~e 12 present ln~ention ~ar superior to any co~ar~ble material cur' 13 ren~ly a~ailable.
14 . EXAMPLE~ll l-Octadecene ~.5 g) and allyl acrylamide (0.~5 g) were di~-16 solved ~n 50 mL o~ ethyl acetat~. 15.0 g of alumlna powder 17 coated w~th polybutadiene (8 miCroh Unisphere0-PBD, ~iotage, 18 lno., Charlottesville, VA) was added to the solution, which w~s 19 t~en shaXen for 10 ~lnu~es. Following evaporation o the so~Vent by rotary evAporation at ~educed pressure, the flask was 21 eva~uat~d and refllle~ w~th nltrogen. The evacuation/refilling 22 procedure was repeated t~ice and the f lasX was capped.
23 ~he ~lask containing the coat~d powder wa~ placed near a 2~ 60Co array and received a total do~ag~ of 1. 5 X 107 Rad during a period of 76 h.
26 ~ollowing irradiation, the ~amp~e was washed with 50 m~ Of 27 h~xane, then 1 oo m~ of hexane containing 1% of glacial scetic 2~ ~cid, then with 50 mL of hexahe~ ~he produc~ was dried at 29 red~ed press~'re to give a pOW~er wh~ch was packed into colu~ns .
30 ~nd us~d ~o ef f ect chrom~tographic separations describ~d in ~-~ ~ ample 2 . The r~tention ti~e of o-xylene was 13 . 6 min .

3., . "..

' ~"; ' ' ' . .

~ 'WO ~/t5385 ~~ 2 1 o 2 '~ 2 ~1 PCTJ~S9~101~2Z

1 EXAMPL~ 12 2 The procedure according to Example ~ 1~ carried out, with 3 eXcepti~n tha~ l-octene 5s u~ed in pl~c~ o~ l-octadeaene. The 4 ~aterial ls used to effect separations and the retention times of o-xylQne and angiotensin II are less than tha~ obtained using ~ ~ateri~1 ~rom Example 8.
7 EXAMP~ 13 8 The procedure according to Example 8 w~s carr~ed out, but g the reaction was not carried out under an atmosph~re of nitrogen.

The etention time of o-xylene wag 13.5 mln. a~d that of angiot~n-ll sin II was ~4 m~n.

12 EXAMPL~ 14 13 ~he pr~ced~e according to Example 8 was carried out but the 1 14 amount o~ allyl~ethacrylate was reduced to 5% and the reacti~n ! 15 was not carried out under an at~osphera of nitro~en. The reten-16 ~ion time o~ o-xylene was 13.1 and t~at of angioten~in~II was 22 17 min.
1~

~2 ~S

3~ ;

. ' ~

Claims

What is claimed is:

CLAIM 1. A chromatographic packing material comprising a coated support material, said coated support material being a chromatographically suitable substrate, and a immobilized coating on said substrate, said coating being a butadiene acrylonitrile copolymer.
CLAIM 2. The chromatographic packing material of claim 1, wherein said copolymer is crosslinked.
CLAIM 3. The chromatographic packing material of claim 1, wherein said copolymer is crosslinked by gamma radiation.
CLAIM 4. The chromatographic packing material of claim 1, wherein said copolymer contains a crosslinking agent.
CLAIM 5. The chromatographic packing material of claim 4, wherein said crosslinking agent is dicumyl peroxide.
CLAIM 6. A chromatographic column having a stationary phase, said stationary phase comprising a coated support material, said coated support material being a chromatographically suitable sub-strate, and immobilized polymeric coating on said substrate, said coatinq being a butadiene acrylonitrile copolymer.
CLAIM 7. The chromatographic column of claim 6, wherein said sup-port material is selected from the group consisting of silica, alumina, diatomaceous earth, zeolite, porous glass and carbon.
CLAIM 8. The chromatographic column of claim 7, wherein said sup-port material is aluminum hydroxide particles.
CLAIM 9. The chromatographic column of claim 8, wherein said sup-port material is spherical lamellar shaped crystals of aluminum hydroxide.
CLAIM 10. The chromatographic column of claim 9, wherein said aluminum hydroxide crystals are bonded together at a central core and extend radially outwardly from a central core.
CLAIM 11. The chromatographic column of claim 10, wherein the par-ticle density ranges from 0.3 to 2.5 g/cm3.
CLAIM 12. The chromatographic column of claim 10, wherein said particles have a diameter of 2 to 150 microns.
CLAIM 13. Method of separating organic materials, said method com-prising the steps of a) providing a bed of packing material selected from the group consisting of silica and alumina, diatomaceous earth, zeolite and porous glass, said packing material having bonded thereto, a polymeric coating, said coating having immobilized coating, said coating being a crosslinked butadiene acrylonitrile copolymer, b) introducing organic materials to said bed, c) adding an eluting fluid to said bed, d) removing said fluid and one of said organic materials from said bed, and e) separating said material removed in step (d) from the fluid.
CLAIM 14, The method of claim 13, wherein said packing material is spherical aluminum hydroxide particles.
CLAIM 15. The method of claim 14, wherein said support material is spherical lamellar shaped crystals of aluminum hydroxide.
CLAIM 16. The method of claim 15, wherein said aluminum hydroxide crystals are bonded together at a central core and extend radially outwardly from a central core.
CLAIM 17. The method of claim 16, wherein the particle density ranges from 0.3 to 2.5 g/cm3.
CLAIM 18. The method of claim 17, wherein said particles have a diameter of 2 to 150 microns.
CLAIM 19. The method of claim 13, wherein said copolymer is derived from a liquid copolymer which contains carboxyl group.
CLAIM 20. The method of claim 13, wherein said copolymer is derived from a liquid copolymer which contains a vinyl group.
CLAIM 21. The method of claim 13, derived from a liquid copolymer which contains terminal reactive groups.
CLAIM 22. The method of claim 13, wherein said copolymer is derived from a liquid copolymer which contains pendent reactive groups.
CLAIM 23. The method of claim 13, wherein said copolymer is derived from a liquid copolymer which is carboxyl terminated.
CLAIM 24. The method of claim 23 wherein said carboxyl ter-minated copolymer be considered long chain dicarboxlyic acids having functionalities between about 1.8 and 2.4.
CLAIM 25. The method of claim 13, wherein said copolymer is predominantly butadiene.
CLAIM 26. The method of claim 25, wherein the ratio of butadiene to acrylonitrile is from about 1:1 to about 10:1.
CLAIM 27. The method of claim 13, wherein copolymer is derived from a liquid copolymer which is vinyl terminated and have reac-tive acrylate vinyl groups.
CLAIM 28. The chromatographic packing of Claim 1, wherein said copolymer is crosslinked thermally.
CLAIM 29. A chromatographic packing material comprising a coated support material, said coated support material being a chromatographically suitable substrate, and an uniform immobi-lized functionalized coating on said substrate, said coating being a polymer having terminal vinyl groups.
CLAIM 30. The chromatographic packing material of claim 29, wherein said polymer is a butadiene acrylonitrile copolymer.
CLAIM 31. The chromatographic packing material of claim 29, wherein said terminal vinyl groups are octadecene.
CLAIM 32. The chromatographic packing material of claim 29, wherein said terminal vinyl groups are octene.
CLAIM 33. The liquid chromatography packing material of Claim 29, wherein said polymer is a butadiene homopolymer.
CLAIM 34. A chromatographic column having a stationary phase, said stationary phase comprising a coated support material, said coated support material being a chromatographically suitable sub-strate, and an uniform immobilized functionalized coating on said substrate, said coating being a polymer having terminal vinyl groups.
CLAIM 35. The chromatographic column of claim 34, wherein said support material is selected from the group consisting of silica, alumina, diatomaceous earth, zeolite and porous glass.
CLAIM 36. The chromatographic column of Claim 35, wherein said support material is aluminum hydroxide particles.
CLAIM 37. The chromatographic column of Claim 36 wherein said sup-port material is spherical lamellar shaped crystals of aluminum hydroxide.
CLAIM 38. The chromatographic column of Claim 37 wherein said aluminum hydroxide crystals are bonded together at a central core and extend radially outwardly from a central core.
CLAIM 39. The chromatographic column of Claim 38 wherein the par-ticle density ranges from 0.3 to 2.5.
CLAIM 40. The chromatographic column of Claim 38 wherein said par-ticles have a diameter of 2 to 150 microns.
CLAIM 41. Method of separating organic materials, said method com-prising the steps of providing a bed of packing material selected from the group consisting of silica, alumina, diatomaceous earth, zeolite and porous glass, said packing material having bonded thereto, a polymeric coating, said coating having an uniform immo-bilized functionalized coating, said coating being a polymer having terminal vinyl groups.
CLAIM 42. The method of claim 41, wherein said packing material is spherical aluminum hydroxide particles.
CLAIM 43. The method of claim 42, wherein said support material is spherical lamellar shaped crystals of aluminum hydroxide.
CLAIM 44. The method of claim 43, wherein said aluminum hydroxide crystals are bonded together at a central core and extend radially outwardly from a central core.
CLAIM 45. The method of claim 44, wherein the particle density ranges from 0.3 to 2.5.
CLAIM 46. The method of claim 45, wherein said particles have a diameter of 2 to 150 microns.
CLAIM 47. The method of claim 46, wherein said polymer is a butadiene acrylonitrile copolymer.
CLAIM 48. The method of claim 45, wherein said terminal vinyl groups are octadecene.
CLAIM 49. The method of claim 45, wherein said terminal vinyl groups are octene.
Claim 50. In a stationary phase for reversed-phase liquid chromatography consisting of a crosslinked, polybutadiene-coated, macroporous, alumina substrate having micropores of a diameter predominately in the range of 50 to 1000 Angstroms, and wherein the alumina substrate is so occludingly coated with said polybutadiene that the integrity of the stationary phase is not adversely affected by extended exposure to liquid environments having a pH of 12; the improvement wherein the polybutadiene coat-ing has attached thereto sufficient alkyl groups whereby the sta-tionary phase exhibits increased hydrophobicity so that the reten-tion time of o-xylene is increased by at least 30% over retention time for a stationary phase coated with polybutadiene having at least about 18 mole percent vinyl groups per butadiene unit.
Claim 51. A stationary phase according to claim 50 wherein said alkyl groups comprise from two to about 30 atoms.
Claim 52. A stationary phase according to claim 51 wherein sub-stantially all of said alkyl groups have 18 carbons atoms.
Claim 53. A stationary phase according to claim 50 wherein said alumina substrate comprises a plurality of microporous platelets bonded together to form a macroporous, substantially spherical particle having a nominal diameter of 8 micrometers.
Claim 54. A stationary phase according to claim 50 comprising at lease 0.05 alkyl side chains per olefin monomer unit of said polymer coating.
Claim 55. In a stationary phase for reversed-phased liquid chromatography consisting of a crosslinked, polybutadiene-coated, macroporous, alumina substrate having micropores of a diameter predominately in the range of 90 to 500 Angstroms, and wherein the alumina substrate is so occludingly coated with said polybutadiene that the integrity of the stationary phase is not adversely affected by extended exposure to liquid environments having a pH of 12, and wherein the polybutadiene contains pendant vinyl groups; the improvement wherein the polybutadiene coating has grafted thereto sufficient alkyl groups whereby the station-ary phase exhibits increased hydrophobicity so that the retention time of o-xylene is increased by at least 30% over retention time for a stationary phase coated with polybutadiene having 18 mole percent vinyl groups per butadiene unit.
Claim 56. A stationary phase according to claim 55 wherein said alumina substrate comprises a plurality of microporous platelets bonded together to form a macroporous, substantially spherical particle having a nominal diameter of 8 micrometers.
Claim 57. A stationary phase according to claim 56 comprising at least 0.1 chromatographically-functional saturated aliphatic side chains per olefin monomer unit of said polymer.
Claim 58. A stationary phase according to claim 57 wherein said alkyl group comprises 14 to 20 carbon atoms.
Claim 59. A method for preparing a stationary phase for liquid chromatography comprising:
a. occludingly coating onto a macroporous alumina substrate having micropores of a diameter predominately in the range of 90 to 500 Angstroms, an unsaturated polybutadiene oligomer having pendant vinyl groups and a molecular weight less than 50,000 Dal-tons, b. partially crosslinking said polybutadiene oligomer to provide on said substrate a polybutadiene coating having pendant vinyl groups;
c. increasing the hydrophobicity of said polybutadiene coat-ing by providing thereon alkyl groups onto said polybutadiene coating, whereby the stationary phase exhibits increased hydrophobicity so that the retention time of o-xylene is in-creased by at least 30% over retention time or a stationary phase coated with polybutadiene having 18 mole percent vinyl groups per butadiene unit.
Claim 60. A method according to claim 59 wherein said alkyl groups are provided by graftlinking of alpha olefins, wherein said graftlinking is initiated by use of chemical grafting agents comprising peroxides or Lewis acids.
Claim 61. A method according to claim 59 wherein said alkyl groups are provided by graftlinking, wherein said graftlinking is initiated by use of electromagnetic radiation.