Group transfer polymerization and initiators therefor

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to Group Transfer Polymerization and to selected 
silicon-based compounds which are useful as initiators therein. 
2. Background 
U.S. Pat. Nos. 4,414,372; 4,417,034; 4,508,880; 4,524,196; 4,581,428; 
4,588,795; 4,645,716; 4,622,372; 4,656,233; 4,681,918; and 4,771,942, and 
and commonly assigned U.S. patent application Ser. No. 707,192 filed Mar. 
1, 1985 and now abandoned, referred to hereinafter as "the aforesaid 
patents and patent applications", disclose processes for polymerizing a 
polar acrylic or maleimide monomer to a "living" polymer in the presence 
of an initiator, which is a tetracoordinate organosilicon, organotin or 
organogermanium compound having at least one initiating site, and a 
co-catalyst which is a source of bifluoride, fluoride, cyanide or azide 
ions or a suitable Lewis acid, Lewis base or selected oxyanion. Such 
polymerization processes have become known in the art as Group Transfer 
Polymerization (Webster et al. J. Am. Chem. Soc. 105, 5706 (1983)). 
Preferred monomers for use in Group Transfer Polymerization are selected 
from acrylic and maleimide monomers of the formula CH.sub.2 .dbd.C(Y)X and 
##STR1## 
and mixtures thereof, wherein: 
X is --CN, --CH.dbd.CHC(O)X' or --C(O)X'; 
Y is --H, --CH.sub.3, --CN or --CO.sub.2 R, provided, however, when X is 
--CH.dbd.CHC(O)X', Y is --H or --CH.sub.3 ; 
X' is --OSi(R.sup.1).sub.3, --R, --OR or --NR'R"; 
each R.sup.1, independently, is a hydrocarbyl radical which is an 
aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical 
containing up to 20 carbon atoms or --H, provided that at least one 
R.sup.1 group is not --H; is: 
(a) a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or 
mixed aliphatic-aromatic radical containing up to 20 carbon atoms; 
(b) a polymeric radical containing at least 20 carbon atoms; 
(c) a radical of (a) or (b) containing one or more ether oxygen atoms 
within aliphatic segments thereof; 
(d) a radical of (a), (b) or (c) containing one or more functional 
substituents that are unreactive under polymerizing conditions; or 
(e) a radical of (a), (b), (c) or (d) containing one or more reactive 
substituents of the formula --Z'(O)C--C(Y.sup.1).dbd.CH.sub.2 wherein 
Y.sup.1 is --H or --CH.sub.3 and Z' is O or NR' wherein R' is as defined 
below; and 
each of R' and R" is independently selected from C.sub.1-4 alkyl. 
Preferred initiators are selected from tetracoordinate organsilicon, 
organotin and organogermanium compounds of the formulas (R.sup.1).sub.3 
MZ, (R.sup.1).sub.2 M(Z.sup.1).sub.2 and O[M(R.sup.1).sub.2 Z.sup.1 
].sub.2 wherein: 
R.sup.1 is as defined above for the monomer; 
Z is an activating substituent selected from the group consisting of 
##STR2## 
and mixtures thereof; 
X', R', R", R and R.sup.1 are as defined above for the monomer; 
each of R.sup.2 and R.sup.3 is independently selected from --H and 
hydrocarbyl, defined as for R above, subparagraphs (a), (c) and (d); 
Z' is as defined above for the monomer; 
m is 2, 3 or 4; 
n is 3, 4 or 5; 
Z.sup.1 is 
##STR3## 
wherein X', R.sup.2 and R.sup.3 are as defined above; 
at least one of any R, R.sup.2 and R.sup.3 in the initiator contains one or 
more initiating substituents of the formula --Z.sup.2 --M(R.sup.1).sub.3 
wherein R.sup.1 is as defined above and M is as defined below; 
Z.sup.2 is a diradical selected from the group consisting of 
##STR4## 
and mixtures thereof, wherein R.sup.2, R.sup.3, X', Z', m and n are as 
defined above; 
R.sup.2 and R.sup.3 taken together are 
##STR5## 
provided, however, Z is 
##STR6## 
and/or Z.sup.2 is 
##STR7## 
X' and either R.sup.2 or R.sup.3 taken together are 
##STR8## 
provided, however, 
##STR9## 
and 
M is Si, Sn, or Ge, provided, however, Z is 
##STR10## 
M is Sn or Ge, and provided, however, when Z.sup.2 is 
##STR11## 
M is Sn or Ge. 
Preferred co-catalysts are selected from a source of bifluoride ions 
HF.sub.2.sup.-, or a source of fluoride, cyanide or azide ions, or a 
source of oxyanions, said oxyanions being capable of forming a conjugate 
acid having a pKa (DMSO) of about 5 to about 24, preferably about 6 to 
about 21, more preferably 8 to 18, or a suitable Lewis acid, for example, 
zinc chloride, bromide or iodide, boron trifluoride, an alkylaluminum 
oxide or an alkylaluminum chloride, or a suitable Lewis base, for example, 
a Lewis base of the formula selected from (R.sup.4).sub.3 M' and 
##STR12## 
wherein: 
M' is P or As; 
X.sup.1 is 
##STR13## 
provided, however, when the monomer is a nitrile, X.sup.1 is 
##STR14## 
each R.sup.4, independently, is: 
(a) a C.sub.1-12 alkyl, C.sub.4-12 cycloalkyl, C.sub.6-12 aralkyl or 
di(C.sub.1-4 alkyl)amino group; 
(b) a group of (a) wherein two or three of the alkyl, cycloalkyl and/or 
aralkyl groups are joined together by means of one or more carbon-carbon 
bonds; 
(c) a group of (a) or (b) wherein the alkyl, cycloalkyl and/or aralkyl 
groups contain within aliphatic segments thereof one or more hetero atoms 
selected from O, N and S; or 
a group of (a), (b) or (c) wherein the alkyl, cycloalkyl and/or aralkyl 
groups contain one or more substituents that are unreactive under 
polymerizing conditions; and 
each R.sup.5 is --CH.sub.2 CH.sub.2 -- or --CH.sub.2 CH.sub.2 -- containing 
one or more alkyl or other substituents that are unreactive under 
polymerizing conditions. 
Additional details regarding Group Transfer Polymerization can be obtained 
from the aforesaid patents and patent applications, the disclosures of 
which are hereby incorporated by reference. 
The present invention provides additional silicon-containing initiators 
which can be used in Group Transfer Polymerization. The initiators of the 
present invention are unique for Group Transfer Polymerization, but they 
are not useful in prior known conventional processes for polymerizing the 
same type of monomer. 
U.S. Pat. No. 4,491,669 discloses alkoxyaminosilanes of the formula R.sub.m 
Si(OR').sub.n (NR"R"').sub.p wherein R is H, short chain alkyl or aryl; R' 
is short chain alkyl or aryl; R" and R"' are separately H, short chain 
alkyl or aryl, at least one being other than H; m+n+p=4; and n and p are 
each at least 1. 
U.S. Pat. No. 4,481,364 discloses silanes of the formula R.sup.1.sub.a 
SiH(OR).sub.3-a wherein R and R.sup.1 are, individually, monovalent 
C.sub.1-10 hydrocarbon radicals and a is 0, 1 or 2. Also disclosed are 
silanes of the above formula wherein H is replaced with a 3-aminopropyl 
group. 
U.S. Pat. No. 4,310,640 discloses various silanes which contain the moiety 
X.sub.3-a Si(R.sup.1).sub.a --CH(R.sup.2)-- wherein R.sup.1 and R.sup.2 
are H or C.sub.1-10 hydrocarbyl; X is halogen, alkoxy, phenoxyl, 
thioalkoxyl, aminooxyl, hydroxyl or amino; and a is 0, 1 or 2. 
U.S. Pat. Nos. 4,251,650 and 4,430,504 disclose silyl ethers, useful as 
free radical polymerization initiators, which contain the moiety 
(R.sup.9)(R.sup.10)(R.sup.11)SiO--C--C-- wherein R.sup.9 can include 
methyl, ethyl, phenyl, benzyl, chloromethyl or a silicon-substituted 
1,2-dioxyethyl moiety (A); R.sup.10 can include chloro, hydroxyl, 
methoxyl, ethoxyl or A; and R.sup.11 can include C1, OH or A. 
U.S. Pat. No. 4,556,722 discloses a process for the preparation of 
aminopropylalkoxysilanes of the formula (R.sup.2)(R.sup.3)NCH.sub.2 
CH(R.sup.4)CH.sub.2 Si(R.sub.a)(OR.sup.1).sub.3-a wherein R and R.sup.1 
are alkyl, R.sup.2 and R.sup.3 are H, alkyl, alkenyl, aminoalkyl or 
phenyl, R.sup.4 is H or alkyl, and a is 0, 1 or 2 by reacting a silane of 
the formula (R.sub.a)HSi(OR.sup.1).sub.3-a with an alkenylamine. 
U.S. Pat. No. 4,506,087 discloses the preparation of alkoxysilanes by 
reacting chlorosilanes of the formula 
(R.sub.a.sup.1)(R.sub.b.sup.2)SiCl.sub.4-a-b wherein the R groups are H or 
hydrocarbyl, a is 0 or 1-3 and b is 0 or 1, (a-b) being equal to or 
greater than 3, with alcohols. 
U.S. Pat. No. 4,558,146 discloses the preparation of vinylaminosilanes of 
the formula R"'CH.dbd.CHSi(NRR').sub.x (R").sub.3-x wherein R' and R"', 
independently, are H or hydrocarbyl, R and R", independently, are 
hydrocarbyl, and x is an integer of 1-3, by reacting an aminosilane with 
an alkyne. 
U.S. Pat. No. 4,579,965 discloses the preparation of vinyl 
tri-t-alkoxysilanes of the formula R"'CH.dbd.CHSi(OCRR'R").sub.3 wherein 
R"' is H or hydrocarbyl, and R, R' and R", independently, are hydrocarbyl, 
by reacting a tri-alkoxysilane with an alkyne in the presence of a 
platinum hydrosilation catalyst. 
There is no suggestion in any of the aforesaid patents that such or similar 
silicon-containing compounds would be useful as initiators in Group 
Transfer Polymerization.

DETAILED DESCRIPTION OF THE INVENTION 
The invention resides in the Group Transfer Polymerization process wherein 
the initiator is of the formula Z.sup.1 --Si(Q').sub.3, (Z.sup.1).sub.2 
--Si(Q').sub.2, [Z.sup.1 (Q').sub.2 Si].sub.2 O or Z.sup.2 --Si(Q').sub.3 
wherein: 
each Q', independently, is selected from R.sup.1, OR.sup.1, SR.sup.1 and 
N(R.sup.1).sub.2 provided, however all of the Q' groups are not R.sup.1 ; 
Z.sup.1 is 
##STR15## 
Z.sup.2 is --CN or --NC; 
X.sup.2 is --OSi(R.sup.1).sub.3, --R.sup.6, --OR.sup.6 or --NR'R"; 
R.sup.6 is 
(a) a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or 
mixed aliphatic-aromatic radical containing up to 20 carbon atoms; 
(b) a hydrocarbyl radical containing at least 20 carbon atoms; 
(c) a radical of (a) or (b) containing one or more ether oxygen atoms 
within aliphatic segments thereof; 
(d) a radical of (a), (b) or (c) containing one or more functional 
substituents that are unreactive under polymerizing conditions; or 
(e) a radical of (a), (b), (c) or (d) containing one or more initiating 
sites; and 
each R.sup.1, independently, is a hydrocarbyl radical which is an 
aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical 
containing up to 20 carbon atoms or --H, provided that at least one 
R.sup.1 group is not --H; 
each of R.sup.2 and R.sup.3 is independently selected from --H and 
hydrocarbyl, defined as for R.sup.6 above, subparagraphs (a) to (e); 
each of R' and R" is independently selected from C.sub.1-4 alkyl. 
By initiating site is meant a group comprising a silicon-containing moiety 
such as --Si(R.sup.1).sub.3, --(Q').sub.3 or --Si(Q').sub.2 -- wherein 
R.sup.1 and Q' are defined as above, derived from a Group Transfer 
Polymerization initiator, including those employed in the present 
invention. 
The initiators employed in this invention are believed to be known or 
obvious compounds, but their use as initiators in Group Transfer 
Polymerization is not suggested in the art. Preferred initiators are those 
wherein: X.sup.2 (in Z.sup.1) is --OR.sup.6 and R.sup.6 is --CH.sub.3 ; 
each Q', independently, is selected from R.sup.1, OR.sup.1 and 
N(R.sup.1).sub.2, provided, however, all of the Q' groups are not R.sup.1 
; R.sup.1 is --CH.sub.3 or --C.sub.2 H.sub.5 ; and R.sup.2 and R.sup.3 (in 
Z.sup.1) are, independently, --H or --CH.sub.3. 
Preferred monomers for use in the present process are polar acrylic 
monomers of the formula CH.sub.2 .dbd.C(Y)X wherein X and Y are defined as 
above; preferred forms of X and Y are those described in the 
aforementioned patents and patent applications. 
The invention also resides in the polymer prepared by the invention 
process. 
The invention further resides in the "living" polymer of the formula 
Rp(Z.sup.3 PQSi[Q'].sub.3).sub.p, Z"PQSi(Q').sub.3, [Z"PQ].sub.2 
Si(Q').sub.2 or [Z"PQ(Q').sub.2 Si].sub.2 O wherein: 
Rp is a hydrocarbyl radical, of valence p, defined as for R.sup.6 (a)-(d); 
Z.sup.3 is a diradical selected from the group consisting of 
--Z'--C(O)--C(R.sup.2)(R.sup.3)--, --C(R.sup.2)(C(O)X.sup.2)--, and 
mixtures thereof; Z', R.sup.2, R.sup.3 and X.sup.2 are defined as above; 
P is a divalent polymeric radical consisting essentially of at least three 
repeat units of at least one polar acrylic and/or maleimide monomer; 
Q is a divalent radical consisting essentially of one or both tautomeric 
forms of a polar acrylic or maleimide unit; 
p is an integer and is at least 1; 
Z" is selected from the group consisting of 
##STR16## 
Z' is O or NR'; and 
Q', R', R.sup.2, R.sup.3 and X.sup.2 are defined as above. 
By "living" polymer is meant a polymer of the invention which contains at 
least one terminal initiating site and is capable of polymerizing further 
in the presence of monomer(s) and catalyst 
Preferred "living" polymers are those wherein P consists essentially of 
repeat units of the formula --CH.sub.2 CH(Y)(X.sup.3)-- wherein X.sup.3 is 
--CN, --CH.dbd.CHC(O)X.sup.2 or --C(O)X.sup.2, and X.sup.2 and Y are 
defined as above, especially wherein Y is CH.sub.3, X.sup.2 is OR.sup.6 
and R.sup.6 is defined as above. Preferred "living" polymers also include 
those wherein Rp is a C.sub.1-8 aliphatic hydrocarbyl radical and those 
wherein p is at least 2. 
The polymers of the present invention include block and star-branched 
polymers prepared by methods similar to those described in the aforesaid 
patents and patent applications. Solutions or dispersions of the "living" 
polymers of the present invention in aprotic solvents are useful for 
casting films and fibers and may be formulated into specialty coating 
compositions for a variety of substrates. The "living" polymers may also 
be capped or quenched as descibed for related "living" polymers in the 
Group Transfer Polymerization art, and the capped or quenched products may 
be molded into shaped articles, including films and fibers. Polymers 
containing functional substituents introduced via monomer, initiator 
and/or capping agent can be post-reacted to provide cross-linked 
structures, block copolymers and the like. 
As is already apparent from the above discussion, the reaction conditions, 
including temperatures, solvents, concentration and preferred monomers and 
catalysts (co-catalysts), are those described in the aforesaid patents and 
patent applications. 
In the following examples of the invention, molecular weight of the polymer 
products (M.sub.w, M.sub.n) was measured by gel permeation chromatography 
(GPC). The polydispersity of the polymer is defined by D=M.sub.w /M.sub.n. 
Unless otherwise specified, the "living" polymer products were quenched by 
exposure to moist air or methanol before molecular weights were 
determined. Parts and percentages are by weight and temperatures are in 
degrees Celsius unless otherwise specified. Acronyms used to identify 
initiator compounds in the examples are defined in Table 1. 
TABLE 1 
______________________________________ 
Acronym Initiator 
______________________________________ 
MPTMS 
##STR17## 
MPTES 
##STR18## 
MPDMS 
##STR19## 
MPDDS 
##STR20## 
MPBMS 
##STR21## 
MPDES 
##STR22## 
MPEDS 
##STR23## 
______________________________________ 
Me = methyl 
Et = ethyl 
EXAMPLE 1 
A. Synthesis of [(1-Methoxy-2-methyl-1-propenyl)oxy]triethoxysilane (MPTES) 
A 3-necked 2-liter flask, equipped with a mechanical stirrer, thermocouple, 
dry-ice condenser, and a dropping funnel, was charged with tetrahydrofuran 
(200 mL) and diisopropylamine (70 mL, 0.50 mol) under an argon atmosphere. 
The mixture was cooled to 0.degree. and n-butyllithium (313 mL, 1.6M in 
hexane) was added dropwise while the temperature was maintained at about 
0.degree.. The mixture was stirred for 30 minutes, followed by dropwise 
addition of methyl isobutyrate (57.3 mL, 0.50 mol). Stirring was continued 
at 0.degree. for an additional 30 minutes and triethoxysilyl chloride (147 
mL, 0.75 mol) was added. The mixture was stirred and allowed to warm up to 
room temperature overnight and filtered under argon to remove the 
precipitated lithium salts. The solvents were evaporated and the liquid 
residue was distilled, first using a Vigreux column, followed by spinning 
band distillation. The total MPTES obtained was 113.3 g (86% yield). This 
was identified by .sup.1 H NMR spectroscpy, IR (infrared) and GC/MS; (gas 
chromatography/mass spectroscopy) b.p. 59.degree.-60.degree./0.15 mm Hg. 
B. Polymerization of Methyl Methacrylate (MMA) 
A 3-neck 100 mL flask equipped with a magnetic stirrer, thermocouple and an 
argon inlet was charged with tetrahydrofuran (THF, 40 mL), 
[(1-methoxy-2-methyl-1-propenyl)oxy]triethoxysilane (MPTES, 0.53 g, 2 
mmol), and methyl methacrylate (2 g, 20 mmol). To this mixture was added 
0.02 mL of tris(dimethylamino)sulfonium bifluoride (TASHF.sub.2, 1M 
solution in MeCN). The temperature rose by 6.degree.. After the exotherm 
subsided, more monomer (8 g, 80 mmol) was added, followed by addition of 
0.03 mL of TASHF.sub.2. The mixture was stirred overnight and the solvent 
was evaporated to give 4.0 g of poly(methyl methacrylate) (PMMA); M.sub.n 
22,500, M.sub.w 57,000, D 2.54. 
The experiment was repeated using a redistilled initiator to give 3.90 g of 
PMMA; M.sub.n 19,400, M.sub.w 57,800, D 2.99. 
EXAMPLE 2 
The procedure of Example 1 was followed using n-butyl acrylate (12.8 g, 100 
mmol) in the place of methyl methacrylate. During the monomer/catalyst 
mixture addition, the temperature rose to 43.4.degree. from 25.2.degree.. 
Normal work-up gave 9.2 g of poly(n-butyl acrylate); M.sub.n 3340, M.sub.w 
12,700, D. 3.79. 
EXAMPLE 3 
The procedure of Example 1 was followed using n-butyl acrylate (12.8 g, 100 
mmol), THF (40 ml), MPTES (0.53 g, 2 mmol), and 1.0 mL of tetrabutyl 
ammonium acetate (0.1M in MeCN). This gave 7.6 g of poly(n-butyl 
acrylate); M.sub.n 9810, M.sub.w 23,600, D 2.40. 
EXAMPLE 4 
To a flask similarly equipped as in Example 1 were added TASHF.sub.2 (0.4 
mL, 0.1M in MeCN), 
[(1-methoxy-2-methyl-1-propenyl)oxy]dimethoxylmethylsilane (MPDMS, 0.83 g, 
4.0 mmol), and THF (50 mL). To the mixture was added MMA (20.0 g, 200 
mmol) at 1.0 mL/min via a syringe pump. The mixture was stirred overnight, 
quenched with methanol and evaporated to dryness. The residue was 
dissolved in acetone and poured into hexane to give PMMA as a white powder 
weighing 20.2 g; M.sub.n 14,900, M.sub.w 42,700, D 2.86. 
EXAMPLE 5 
The procedure of Example 4 was followed except that TASHF.sub.2 was 
replaced by tetrabutylammonium 3-chlorobenzoate (0.40 mL, 0.1M in MeCN). 
Normal work-up followed by precipitation from hexane gave 20.3 g of PMMA 
as a white powder; M.sub.n 16,600, M.sub.w 46,200, D 2.79. 
EXAMPLE 6 
The procedure of Example 4 was followed using methyl methacrylate (20.0 g, 
200 mmol), THF (50 mL), TASHF.sub.2 (0.40 mL, 0.1M in MeCN), and 
[(1-methoxy-2-methyl-1-propenyl)oxy](dimethylamino)dimethylsilane (MPDDS, 
0.81 g, 4.0 mmol). Evaporation of the solvent gave 13.3 g of PMMA; M.sub.n 
15,700, M.sub.w 64,100, D 4.10. 
EXAMPLE 7 
The procedure of Example 4 was followed using the reagents of Example 6 
except that tetrabutylammonium 3-chlorobenzoate (0.40 mL, 0.1M in MeCN) 
was used in the place of TASHF.sub.2. Normal work-up gave 17.0 g of PMMA; 
M.sub.n 18,300, M.sub.w 49,900, D 2.73. 
EXAMPLE 8 
The procedure of Example 6 was followed using TASHF.sub.2 (0.40 mL, 0.10M 
in MeCN) as catalyst and 
[(1-methoxy-2-methyl-1-propenyl)oxy]bis(dimethylamino)methylsilane (MPBMS, 
0.93 g, 0.40 mmol) as initiator. Normal work-up gave 1.0 g of powdered 
white PMMA. 
EXAMPLE 9 
A reactor equipped as described in Example 1 was charged with MMA (10.0 g. 
100 mmol), MPTES (0.53 g, 2.0 mmol) and THF (20 mL). This was immediately 
followed by the dropwise addition of tetrabutylammonium acetate in THF as 
catalyst. After an initial induction period of about 10 minutes, a 
vigorous reaction ensued. After the exotherm subsided, methanol (5 mL) was 
added and the solvents were evaporated to give 9.0 g of PMMA; M.sub.n 
33,800, M.sub.w 274,000, D 8.11. 
EXAMPLE 10 
A reactor equipped as described in Example 1 was charged with potassium 
bifluoride (0.40 g, 5.13 mmol), dimethyl formamide (2.0 mL), acetonitrile 
(30 mL), and MPTES (1.32 g, 5.0 mmol). Then MMA was added at 1.0 mL/min 
and the resulting mixture was stirred overnight. After addition of 
methanol, the solvents were evaporated and the residue was precipitated 
from methanol to give 10.3 g of PPMA; M.sub.n 2400, M.sub.w 5740, D 2.39. 
EXAMPLE 11 
A reactor equipped as described in Example 1 was charged with ZnBr.sub.2 
(1.0 g, 4.4 mmol), 1,2-dichloromethane (50 mL) and MPTES (0.53 g, 2.0 
mmol). Then MMA was added dropwise at 1.0 mL/min. The resulting mixture 
was stirred overnight and evaporated; the residue was dried to give 3.8 g 
of white PMMA which was purified by precipitation from MeOH to give 2.2 g 
of white, powdery solid PMMA; M.sub.n 29,800, M.sub.w 264,000, D 8.87. The 
product contained about 10% of high molecular weight material. When 
correction was made for the high molecular weight component, the GPC 
analyses gave M.sub.n 29,800, M.sub.w 70,000, and D 2.35. 
EXAMPLE 12 
The procedure of Example 11 was followed using n-butyl acrylate (12.8 g, 
100 mmol). Normal work-up gave 11.2 g of poly(n-butyl acrylate) which was 
further dried to give 10.0 g of polymer; M.sub.n 4750, M.sub.w 5900, D 
1.24. 
EXAMPLE 13 
The procedure of Example 4 was followed using MMA (20 g, 200 mmol), 
TASHF.sub.2 (0.40 mL, 0.1M in MeCN), THF (50 mL), and 
[(1-methoxy-2-methyl-1-propenyl)oxy]diethoxymethylsilane (MPDES, 0.94 g, 
4.0 mmol). Normal work-up gave 10.9 g of white solid PMMA which was 
dissolved in acetone and poured into hexane to give 10.6 g of PMMA as a 
white powder (identified by .sup.1 H NMR); M.sub.n 27,900, M.sub.w 
109,000, D 3.91. 
EXAMPLE 14 
The procedure of Example 4 was followed, replacing MPDMS by 
[(1-methoxy-2-methyl-1-propenyl)oxy]dimethylethoxysilane (MPEDS, 0.82 g, 
4.0 mmol). Normal work-up gave 20.1 g of PMMA; M.sub.n 7100, M.sub.w 
14,600, D 2.06. 
EXAMPLE 15 
The procedure of Example 14 was followed, replacing TASHF.sub.2 by 
tetrabutylammonium 3-chlorobenzoate (0.40 mL, 0.1M in MeCN). Work-up gave 
20.9 of PMMA; M.sub.n 10,600, M.sub.w 23,200, D 2.18. 
EXAMPLE 16 
Polymerization of MMA Initiated by 
[(1-Methoxy-2-methyl-1-propenyl)oxy]trimethoxysilane (MPTMS) Prepared in 
Situ 
A 3-necked flask equipped with an argon inlet, a stirrer and a thermocouple 
was charged with methyl .alpha.-bromoisobutyrate (1.81 g, 10 mmol), Zn 
metal (0.65 g, 10 mmol) and tetramethoxysilane (20 mL). After an 
accompanying 5.degree. exotherm had subsided, methyl methacrylate was 
added and the mixture was stirred overnight. Then tetrabutylammonium 
fluoride (0.20 mL, 1M in THF) was added. After stirring for 4 h, methanol 
(10 mL) was added and the solvents were evaporated. The residue was 
dissolved in ethyl acetate, washed first with water containing a few drops 
of HCl and then with saturated sodium chloride. The organic layer was 
dried over MgSO.sub.4, filtered and evaporated to give 6 g of PMMA; 
M.sub.n 90,000, M.sub.w 171,000, D 1.90. The PMMA was dissolved acetone 
and precipitated from methanol; M.sub.n 62,000, M.sub.w 162,000, D 2.59. 
EXAMPLE 17 
A. Preparation of Tri(t-butoxy)cyanosilane and isocyanosilane 
To a stirred solution of 9 g (57.6 mmol) of tetraethylammonium cyanide in 
80 mL of anhydrous acetonitrile was added 17.2 g (57.6 mmol) of 
tri(t-butoxy)chlorosilane. The resulting solution was cooled to 
-20.degree. whereupon a precipitate formed. Then 35 mL of anhydrous ethyl 
ether was added, and the cold mixture was filtered under argon. The 
filtrate was evaporated under reduced pressure, and the residue was 
treated with ether and filtered under argon. The filtrate was concentrated 
under reduced pressure and distilled in a spinning band column. The 
products were collected in three fractions, and the third fraction (4.4 g, 
b.p. 44.degree./0.4 mm) consisted of tri(t-butoxy)cyanosilane (IR: 2198 
cm.sup.-1) and tri(t-butoxy)isocyanosilane (IR: 2104 cm.sup.-1). Anal 
Calcd for C.sub.13 H.sub.27 O.sub.3 SiN: C 57.10; H 9.95; N 5.12; Si 
10.27. Found: C 57.00; H 9.88; N 5.42; Si 9.97; Cl 0.14. 
B. Polymerization of MMA Initiated by Tri(t-butoxy)cyanosilane and 
isocyanosilane 
The following procedure was performed under a dry argon atmosphere. 
Tetraethylammonium cyanide (30 mg, 0.19 mmol) was treated with 9 mL of 
N,N-dimethylformamide to dissolve, and then 25 mL of tetrahydrofuran was 
added to obtain a honogeneous solution. Then 0.54 g (0.61 mL, 2 mmol) of 
the mixed silane product (third fraction) of Part A was added. Then 10 g 
(10.8 mL, 100 mmol) of MMA (purified over a column of neutral alumina 
under argon) was added rapidly. During 3 minutes only a slow temperature 
increase of 1.degree. was observed, and then a rapid exothermic 
polymerization caused a temperature rise from 25.degree. to 51.degree.. 
After the reaction mixture had returned to room temperature, a sample was 
removed for NMR analysis. The analysis showed that conversion to polymer 
was 65%. The polymer was isolated by precipitation with aqueous methanol. 
GPC showed bimodality, with approximately equal amounts of high and low 
molecular weight polymer: M.sub.n 8400, M.sub.w 64,600, D 7.69. Estimates 
of the high and low molecular weight portions showed a low molecular 
weight fraction M.sub.n 4190, M.sub.w 6760; and a high molecular weight 
fraction: M.sub.n 67,100, M.sub.w 115,000. NMR analysis of the whole 
polymer showed it be 58.1% syndiotactic, 36.5% heterotactic and 5.4% 
isotactic. 
BEST MODE FOR CARRYING OUT THE INVENTION 
The best mode presently contempalted for carrying out the invention is 
represented by Examples 2, 4 to 8, 12, 13, 15 and 17.