Process for preparing high molecular weight polyaryloxysilanes from lower molecular weight form

Dunnavant, W. R.

English

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NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
WASHINGTON, D.C. 20546 
~ ~ ~ / ~ c i e n t i f i c  & Technical Information Division 
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SUBJECT: Announcement of NASA-Owned U.S, Patents  i n  STAR 
I n  accordance with the  procedures contained i n  the  Code G P  
t o  Code US1 memorandu,m on t h i s  subject ,  dated June 8, 1970, 
the  attached NASA-owned U.S. patent  is  being forwarded f o r  
abs t rac t ing  and announcement i n  NASA STAR. 
The following information is provided: 
U.S. Patent  No. 
Corporate Source 
Supplementary 
Corporate Source 
: Bat t e l l e  Memorial I n s t i t u t e  
NASA Patent  Case NO.: XMF-08674 
\ Please note t h a t  t h i s  patent  covers an invention made by an 
employee of a NASA contractor .  Pursuant t o  9305(a) of t he  
NAS Act, t he  name of the Administrator of NASA appears on the  
f i r s t  page of t h e  patent ;  however, t he  name of the  ac tua l  
inventor (author) appears a t  t he  heading of Column No. 1 of 
t h e  Specif ica t ion,  following the  words ", . , with respect  t o  
an invention of .  , . ," J 
Enclosure : 5 M c ,  U (NASA CR OR TMX OR AD NUMBER) (CATEGORY) 
copy of Patent  ' 
https://ntrs.nasa.gov/search.jsp?R=19710019331 2020-03-17T03:15:43+00:00Z
3,370,039 United States Patent Ofice Patented Feb. 20. 1968 
1 2 
ature for the volvmerization reaction rcsnlts in a cross- 
3,370,039 
PROCESS FOR PREPARATION OF HErGH-MOLEC- 
ULAR-WEIGHT 320kYARY&OX~SILANES 
James E. Webi~, AdraainistraQo~ of the National Aero- 
nautics and ~ b a e e  Adl~ministration with respect to an 
invention of William PI. Dunnayant, Coiiumbus, Ohio 
No Drawing. Filed Feb. 17, 1967, Sen. No. 617,775 
8 Claims. (C1. 260-47) 
ABSmAGT OF THE DISCLOSURE 
A process for increasing the molecular weight of poly- 
aryloxysilaae polymers and upgrading their properties so 
that they can be fabricated into useful articles. Polyaryl- 
oxysilanes prepared by the reaction of a dianilinosilane 
and an organic diol, for example, dianilinodiphenylsilane 
and p,pf-hiphenol, are mixed with a small amount of the 
dianilinosilane monomer and the mixture is heated under 
vacuum or inert gas sweep for at least thirty minutes at 
200 to 300" C. This treatment converts the polymer from 
a brittle, low-molecular-weight form to a non-brittle, high- 
n:o!ecular-weight material suitable for further processing. 
The invcniion described herein was made in the per- 
formance of work under a NASA contract and is subject 
to the provisions of Scction 305 of the National Aeronau- 
tics and Space Act of 1958, P.L. 85-568 (72 Stat. 435, 
42 U.S.C. 4257). 
This invention relates to polymer processing and more 
particularly to a process for preparing high-molecular- 
weight polyaryloxysilanes from lower-molecular-weight 
forms of the same. 
Folyaryioxysilane polymers, exemplified by the formula 
linked insolubfe pblymer which is not amenable to furtlicr 
fabrication except by con~pression molding 2nd ~ V ~ I L ' I  
therefore has limited utility. 
In pilot-scale and larger operations, however. the po'y- 
mer produced by this reaction has not been suitable icr 
further fabrication. Even when the pu~ity of the starting 
monomers, the reaction atmosphere and tensperaturc ar- 
carefully controlled, a brittle, lo~i-moiecuiar-~7~eigi-t 
(about 32,000 to 44,000) product similar to the sniait- 
scale polymer produced from impure monorscr is oh- 
tained. In order to obtain a material with useful engitiecn- 
ing properties a method must be provided to convert Ihs 
product to a higher-molecular-weight, non-brittle po'iyilier. 
It is therefore an object of this invention to provide a 
process for converting brittle, low-molecular-weigh1 poIy- 
aryloxysilanes to non-brittle, high-molecular-wei& form. 
Still another object is to provide a process for t~eating 
polyaryloxysilanes prepared in reiativcly large-scale oper- 
ations to improve the physical and n-iechanical properties 
thereof. 
Other objects and advantages of the Jnvefitlon wiU be 
apparent from the following description and claims. 
In the present invention low-molecular-weiqh poil~ai yi- 
oxysilanes are converted to high-molcc~ilar-bei6i~t form 
by heating the polymer together with a small ail-nccn~ of 
dianilinosilane monomer under a vacuun-r ol a.i meit gas 
sweep. The n~olecular weight is subslat~iially incleascc', 
typically 45 to 90 percent, and brittleness and poor me- 
chanical properties are eliminated. The process is rerro- 
ducible for large-scale operation, and it allows the piac- 
tical fabrication and use of polyaryloxysilanes for numcr- 
ous applications. 
Although this invention is not to be understood as lim. 
ited to a particular theory, it is postulated that a portron 
of the silane mollorner is theimally destroyecF -in l'-ie 
polymerization reaction, and the growing polymer clz.iirr 
is terminated by reaction with the phenol reactant. The 
upgrading of polymer properties probably rcsults from 
40 coupling together a phenol-terminated polymers by rhc 
additional silane monomer provided in the prcseil* pi occss 
I-Iowever. this effect cannot be produced by pToviding a*: 
excess of this reactant in the initial po1ymeriz;ition ~ e -  
action; a second heating step in the prescnce or silnne 
45 monomer is required. The occurrence of fullher chcn- 
ical reaction in this step is indicated by !he euoiuiior: of 
aniline. 
offer outstanding properties for materials applications in 
the acrospace field. These polymers show good therillal 
stability and stability to ultra-violet radiation in a vacuum, 
and they are potentially useful as thermo-plastic, thermo- 
setting or elastomeric material for structures, laminates 
or coatings which are to be subjected to the severe envi- 
ronment of outer space. 
Polyaryloxysiianes are prepared by a polycondensation 
reaction of an organic d id  with a dianilinosilane, p,p'- 
diphenol and dianilinodiphenylsilane for the polymer 
having the formula given above. This process is disclosed 
and claimed in copending application Ser. No. 506,135, 
field Nov. 2, 1965, by James E. Curry. The reaction is car- 
ried out by heating an equimolar mixture of the reactants 
under vacuum or inert amosphere to a temperature over 
200" G. In laboratory scale preparations a high-molecular- 
weight, tough, non-brittle polymer having properties suit- 
able for further processing can be obtained in this process 
by careful control of the purity of the silane monomer 
and exclusion of air and moisture from the reaction zone. 
Impurities in the silane monomer result in a brittle poly- 
mer of lower molecular weight (less than 45,000) which 
is not suiiahlc for fabrication into useful products. The 
presence of air or the use of an excessively high temper- 
The present invention is broadly applicable to polymer s 
naving the general formula 
50 
1 -Lo-s,-o-Rl- 
L a _I" 
55 
where Hi is an aryl or alkyl group and R' 1s an aiyiene 
group. These polymers are prepared by reacting the ep- 
propriate dianilosilane such as dianllinod1gl1enyIs~lc!ne, 
ianilinon~ethyIphenylsilane, dianilinodirnelhylsil~ne or dl- 
60 anilinomethylvinylsilane with a diol having the dcsi,cd 
R' group, for example, hydroquinonc, resorcinol, p p'- 
biphenol, 2,7-napthalenediol, 2,2-propancb~s(4-kydroxv- 
benzene) and 4,4'-dihydroxydiphenylelber. Although t!~e 
invention will be described below primarily wri l~  refer - 
65 ence to the polymer produced by reaction of 2.p'-hiphenol 
with dianilinodiphenyl silane, it is to be rrnderstood that 
the same mechanism applies to the e ~ z + i ~ e  grovp. The 
molecular weight at which the transition from tough in 
britt!e polymer occurs will vary somcw~-rat with the par - 
70 ticular polymer, but in general the same condltioi~s car] 
be used in each case for converting the polymer to a 
higher-molecular-weight form. 
3,370,039 
3 44 
'The brittle po1y.arylsiloxane polymer obtained by reac- Example II 
dion oU a drol wilh a dianilinosilane is converted to non- A 10,644 gram portion of polymer prepared in the run 
b*~t"L:, hlghcr-molecular-weigbt form by heating a mix- described above wherein a 6.5 hour heating time was lrire ~ 1 :  the polymer and a small amount of dianilinosilane used was heated to in a reactor under a nitrogen 
nloncnl2r under vacuum or an inert gas sweep. The 5 atmosphere and 533 grams of dianilinodiphenylsilane was 
aeilounl of diariiiinosrlane added can be from 2 to 10 added. The resulting mixture was and heated 
Wrta 1:) weight per hundred parts of polymer, and about under a nitrogen atmosphere at 225 to 250" C. until 5 p ~ t s  i  tile picferred amount. aniline began to evolve. The mixture was then held at 
A "Izm~cratuie 200 to 3000 '. can be in 225 to 250" C. for 45 to 60 nli~lutes under a vacuum of 
i 1- 1,3 beating ster, and about 225 to 250" C. is preferred. about 25 inches of mercury with periodic to 
He;ltrr;,n for a period of at least 30 minutes under a facilitate aniline removal. The reactor was then prcs- 
5trealx 3 f  an inti: gas such as nitrogen or under a vacuum surized with nitrogen to 30 to 40. pounds per sqLlare inch 
nl l e -~ \"Lhut  25 inches of mercury is requircd for maxi- and the polymer was extruded inlo rods a one- 
mum ,nciease in molecufar weight. Although not critical, inch opening in the bottom of the reactor. ~h~ 
'I. 1s preferred to first heat the polymer until it melts 15 rods were tough, and they could be immersed in liquid 
bboti 180' c.1 under vacuum or inert atmosphere and nitrogeL, for 30 without developing any apprecia- 
~':i?n odded the silane monomer with stirring so that an ble brittleness. The average molecular weight of the 
ir,tarrale II~IA~LITC can be obtained in the molten state. product was 57,000. 
Th- resrlltlng upgraded polymer can be fabricated into Polymer samples which were subjected to heating un- 
xisei181 fo3~31b such as sheets, nloldins, fibers or coatings 20 der inert atmosphere or vacuum in the manner described 
ky co~~vcntionai methods, including extrusion, compres- above, but in the absence of added silane monomer, failed 
s i m  mu!d:ng and solvent casting. 
-1 ' 
to show any substantial improvement with regard to  mo- 
srlls irivcntion is further illustrated by the following lecular weight or brittleness. -j-he use of an excess of silane 
exa~pics, monomer in the polymer preparation likewise failed lo 
Example I 25 effect anv substantial im~rovement. 
Poiyni;/loxy_ys,lune polymer was prepared on a pilot- 
piai,t scale by the following proccdure. A charge of 
11,793 grams dianilinodiphenylsilarze and 5,980 grams 
p p'-i-uphenol was added to a ten-gallon stainless steel 
rcactor e q l i f ~ e d  with an oil-fed heating jacket, an agita- 
lor, and provisiclns for maintaining a nitrogen gas atmos- 
The above examples are merely illustrative and are not 
to be understood as limiting the scope of the invention, 
which is limited only as indicated by the appended claims. 
What is claimed is: 
1. The process for treating a polyaryloxysilane goly- 
mer having the formula 
- -. - 
pheie. Oii heated to 221" C. was circulated through the 
~cactac gailtet, and after 60 minutes the temperature of 
1 l? I 
-0-bi-0-R'- 
:he r i ~ ~ t  on rnl~tilie reached 200" C. The polynlerization 35 I.- a A. 
ieacl,oii 'has lhen initiated, as evidenced by evolution of where K is an aryl or alkyl group and R' is an arylene 
by-yroi-iuci G%a~line, which was swept from the reactor by group, snid polymer having been prepared by reaction 
a S I K C L : ~  of h~ated,  dry nitrogen. The mixture was healed of a dianilinosilane and a dlol, which comprises mixing 
ior four rorrrs, tile temperature rising to 240" C. The qo said polymer with a small amount of said dianilinosilane 
mixture was further heated under agitation for one hour, and heating the resulting rnivture under a vacuum or an 
dt whrch t ~ m e  evolution of aniline ceased. The product inert gas sweep at a temperature of 200 to 300" C., where- 
p ~ i y n ~ e r  was then recovered at a yield of 99 percent. by saidpolymer is converted to non-brittle, hi&er-molecu- 
The, avc, rge molecular weight of the product, as deter- 1ar-weight form. 
mmei! by gel permeation chromotography was 43,000. 2.  The process of claim 1 wherein said dianilinosilane 
ProdLLCt colaid be injection-molded at 125" C, under 45 is provided in said mixture at a proportion of 2 to 10 
n-,llci pressuie or into film, but the films and parts weight per 100 parts of saidpolymer. 3. The process of claim 2 wherein said mixture is heat- 
n~aided samples were brittle. ed for a period of at least 30 minutes. Fullher runs were carried out using the same equip- The process of wherein said temperature is 
mcnt aad rcac"i~nt charge. In one of these runs the above 50 about 225 to 2500 C. 
p ocedsrre was vsed except that the mixture was agitated 5. The process of claim 3 wherein said mixture is 
t i ~ r o ~ g l ~ ~ ~ ~ t  the reaction, and a total heating time of 6.5 heated under a vacuum of at least about 25 inches of 
hoi~rs  WJS L ~ ~ ~ d .  In another run a vacuum was applled mercury. 
v 11eo e~oBution of aniline began, and a heating time of 6. The process of claim 3 wherein said dianilinosilane 
5 hours was used. The average molecular weights for 55 is provided in said mixture at a proportion of about 5 
t less rintl5, as determined by gel permeation chromotog- parts by weight per 100 parts of said polymer. 
s ~ p h y ,  wLre 49 0100 and 32,000, respectively. The product 7. The process of claim 3 wherein said dianilinosilane 
,n each nun was brittle. is dianilinodiphenylsilane and said dial is p,pl-biphenol. 
Ten-gram samples of polymer from each of the three 8. The Process of chim 7 wherein the starting mo- 
runs c?es*nbed above were mixed with 5 weight percent 60 lecular weight of said polymer is from about 32,000 to 
dran l,nodiphenyisilane and heated under vacuum for 44,000. 
0 66, one and oni:-half hour, respectively, at 225, 250, and References Cited 
250" scspeclively. In each case the brittle polymer was 737,230 911955 Great Britain. 
~onvcried to tough, non-brittle form, and the molecular 65 
weighis of the samples after this treatment were 63,000, DONALD E. CZAJA, Primary Examilzer. 
58,000, and 41,000, respectively. M. I. MARQUIS, Assista~zt Exanziner. 


Process for preparation of high-molecular- weight polyaryloxysilanes Patent

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