Multi-block coupled polyoxyalkylene copolymer surfactants are prepared from individual blocks of polymers and copolymers of alkylene oxides by reacting these with bifunctional compounds to form polycarbonate esters and polyformals.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to polyformal and polycarbonate copolymers 
which are useful as surfactants. More specifically, individual blocks of 
polymers and copolymers of alkylene oxides are reacted with either a lower 
dialkyl carbonate or formaldehyde to form blocks linked by formal or 
carbonate groups. 
2. Prior Art 
Surface active multi-block polyoxyalkylene copolymers are well known in the 
art. This is evidenced by the teachings of U.S. Pat. No. 2,950,310 wherein 
esters are produced from polyoxyalkylene glycols, dibasic acids and 
monohydric alcohols. The dibasic acids contain from 2 to 12 carbons. There 
is no teaching of the particular surface active compounds of this 
invention. The coupling compounds employed in the present invention 
contain only one carbon atom. Further, there is no teaching of the use of 
multi-block coupling such as taught by the present invention. 
U.S. Pat. No. 2,905,719 teaches the preparation of surface active formals 
whereby an alkyl group is linked to a polyoxyethylene group through a 
formal linkage. There is no teaching of the use of multiple formal 
linkages joining multi-block polyoxyalkylene groups. Further, the present 
invention does not link an alkyl group to a polyoxyalkylene group. The 
present invention is directed to linking blocks of polyoxyalkylene groups 
to one another. 
SUMMARY OF THE INVENTION 
It has been discovered that surface active compounds may be prepared by 
linking polyoxyethylene and polyoxypropylene polymers through the use of 
coupling agents such as formaldehyde or a dialkyl carbonate. The blocks of 
hydrophobic and hydrophilic polymers are reacted with a dialkyl carbonate 
in the presence of an alkaline catalyst. Subjecting the mixture to heat 
and distilling off an alkanol results in an ester exchange which 
effectively links the hydrophobic and hydrophilic blocks together. The 
blocks of hydrophobic and hydrophilic polymers may also be linked through 
the use of formaldehyde. Formaldehyde is added to a mixture of the 
hydrophobic and hydrophilic block polymers in the presence of an acid 
catalyst. The water, which results from the reaction of formaldehyde with 
the hydroxyl terminated block polymers, is removed by an azeotropic 
distillation with a water immiscible solvent such as benzene. 
The various polyoxyethylene or polyoxypropylene polymers can be pre-reacted 
to form blocks of varying structure and molecular weight. For example, it 
is possible to link several polyoxypropylene groups of about 400 molecular 
weight using a dialkyl carbonate or formaldehyde. Similar linkages can be 
obtained from polyoxyethylene groups. These blocks can then be linked 
together, again employing either a dialkyl carbonate or formaldehyde, to 
form any desired hydrophobic or hydrophilic ratio. It is generally well 
known that polyoxyalkylene blocks of molecular weights below 900 exhibit 
poor detergency properties as taught by U.S. Pat. No. 2,674,619. Thus, it 
is surprising that these short hydrophilic and hydrophobic blocks coupled 
by polyformal or polycarbonate linkages would display such high surface 
activity. It is further surprising that short random block hydrophilic and 
hydrophobic copolymers exhibit surface activity. 
DESCRIPTION OF THE PREFERRED EMBODIMENT 
In accordance with this invention polyoxyalkylene polymers are coupled by a 
reaction with either a dialkyl carbonate or formaldehyde. The preparation 
of a product formed by coupling with a dialkyl carbonate is exemplified by 
the following equations: 
##STR1## 
where Y is the residue of an alkylene glycol containing therein two 
terminal hydroxyl groups, minus the terminal hydrogen atoms, M is a 
hydrophilic chain of units selected from the group consisting of 
oxyethylene and oxyethyleneoxypropylene units wherein the oxyethylene 
content of said hydrophilic chain is from about 75 to 100 weight percent 
and the oxypropylene content is from 0 to about 25 weight percent, the 
number of oxyethylene and oxypropylene groups in M being from about 2 to 
about 15, N is a hydrophobic chain of units selected from the group 
consisting of oxypropylene units and oxyethyleneoxypropylene units wherein 
the oxypropylene content is from about 75 to 100 weight percent and the 
oxyethylene content is from 0 to about 25 weight percent, the number of 
oxyethylene and oxypropylene groups in N being from about 2 to about 10, Q 
is selected from the group consisting of methyl, ethyl and propyl. 
The above product will probably also contain species which are terminated 
with an alkyl carbonate group rather than hydroxyl groups similar to the 
following formula: 
##STR2## 
wherein Q, Y, and N are as defined above. If the molar quantities of 
dialkyl carbonate appreciably exceed those of the oxyethylene and 
oxypropylene units then the alkyl carbonate terminated species will 
predominate. Generally, for every mole of oxyalkylene units, 0.5 to about 
1.0 mole of alkyl carbonate is required to form the hydroxy terminated 
products. This is due to the volatility of the alkyl carbonates. Molar 
ratios greater than 1 mole of alkyl carbonate to 1 mole of oxyalkylene 
unit, preferably 1.25 to 2 of alkyl carbonate to 1 mole of oxyalkylene 
unit are required to form a compound which is predominantly terminated 
with the alkyl carbonate. The coupling reaction with the dialkyl carbonate 
is carried out at a temperature range of about 100.degree. to 200.degree. 
C. in the presence of an alkaline catalyst. Examples of such catalysts are 
sodium carbonate, potassium carbonate, sodium methoxide, sodium ethoxide, 
potassium methoxide and potassium ethoxide, sodium hydroxide, potassium 
hydroxide and mixtures thereof. The preferred alkaline catalyst is 
potassium carbonate. The amount of catalyst employed may vary from about 
0.01 to about 1 weight percent based on the total weight of reactants. The 
amount of alkaline catalyst is not critical, however it is necessary that 
the coupling reaction with the dialkyl carbonate occur at an alkaline pH. 
The pH may vary from 8 to 11, preferably from 8 to 10. The reaction with 
dialkyl carbonate occurs as the result of an ester interchange. As the 
temperature is raised from 100.degree. to 200.degree. C. an alkanol is 
distilled off resulting in the ester interchange. This results in the 
coupling of oxyalkylene groups through the carbonate groups. 
The preparation of a product formed by coupling with formaldehyde is 
exemplified by the following equations: 
##STR3## 
This product will also probably contain species which are terminated with a 
methylol group rather than hydroxyl groups similar to the following 
formula: 
##STR4## 
wherein Y, M, and N are defined as above. A mole ratio of 0.5 to about 1.0 
of formaldehyde to 1.0 mole of oxyalkylene unit results in the 
preponderant formation of the hydroxy terminated species. This is due to 
the volatility of the formaldehyde. Mole ratios greater than 1 mole of 
formaldehyde to 1 mole of oxyalkylene unit, preferably 1.25 to 2.0 moles 
of formaldehyde to 1 mole of oxyalkylene unit, are required to form a 
compound which is predominantly terminated with methylol groups. 
The compounds prepared by coupling the polyoxyalkylene condensation 
products with formaldehyde are carried out at a temperature range of about 
25.degree. C. to 150.degree. C. in the presence of an acid catalyst. 
Examples of such catalysts are sulfuric acid, hydrochloric acid, 
hydrobromic acid, p-toluene sulfonic acid, phosphoric acid, 
trifluoroacetic acid, methane sulfonic acid and trichloroacetic acid. The 
preferred catalyst is sulfuric acid. The amount of catalyst employed may 
vary from 0.01 to about 3 weight percent based on the total weight of 
reactants. The coupling reaction is carried out in the presence of a water 
immiscible solvent which is employed to remove the water of reaction by an 
azeotropic distillation. Examples of such solvents are benzene, toluene, 
xylene, hexane and cyclohexane. 
The pH of the reaction may vary from about 2 to about 6, preferably from 3 
to 6. 
The polyoxyalkylene polymers are prepared by reacting the alkylene oxide 
with a base compound containing a plurality of active hydrogen atoms. The 
base compounds preferably have molecular weights of less than 100. 
The term "active hydrogen atom" is well known to those skilled in the art. 
It is sufficiently labile to react with ethylene, propylene or butylene 
oxide and it reacts with methyl magnesium iodide, liberating methane 
according to the classical Zerewitinoff reaction. The active hydrogen 
atoms are normally activated by being members of a functional group such 
as a hydroxyl group, a phenol group, a carboxylic acid group, a basic 
nitrogen group such as an amine group, a hydrazine group, an imine group 
or an amide group. Active hydrogen atoms may also be activated by 
proximity to carbonyl groups such as acetoacetic ester. Examples of active 
hydrogen compounds, which may be used as base compounds, include ethylene 
glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene 
glycol, amylene glycol, hexylene glycol, heptylene glycol and octylene 
glycol. 
The alkylene oxides which may be employed are ethylene oxide, as the source 
for the hydrophile and propylene and butylene oxides as the source for the 
hydrophobes. Those preferred are ethylene oxide and propylene oxide. 
The individual polyoxyalkylene polymers and copolymers may have a molecular 
weight ranging from 200 to 2000 preferably from 200 to 1000. If desired, 
heteric polyoxyethylene polyoxypropylene polymers may also be employed. 
The polyoxyalkylene polymers and copolymers employed in this invention are 
generally prepared by carrying out the condensation reaction of the 
alkylene oxide with the base compound in the presence of an alkaline 
catalyst in a manner well known to those skilled in the art. Any of the 
types of catalysts commonly used for alkylene oxide condensation reactions 
may be employed. Catalysts which may be employed include sodium hydroxide, 
potassium hydroxide, sodium methylate, sodium ethylate, potassium acetate, 
sodium acetate, trimethylamine and triethylamine. After the condensation 
reaction is completed, the catalyst may be removed from the reaction 
mixture by any known procedure such as neutralization, filtration or ion 
exchange. The condensation is preferably carried out at elevated 
temperatures and pressures. The condensation products are then subjected 
to the coupling reaction to form the products of the invention. 
The products of this invention can be exemplified by the following formula: 
EQU H--R--Y--R [Z--M--Y--M].sub.a [Z--N--Y--N].sub.b -- R--Y--R--H 
wherein 
Z is selected from the group consisting of 
##STR5## 
Y is the residue of an alkylene glycol containing therein two terminal 
hydroxyl group, minus the terminal hydrogen atoms, 
M is a hydrophilic chain of units selected from the group consisting of 
oxyethylene or a mixture of oxyethylene and oxypropylene units wherein the 
oxyethylene content is from about 75 to 100 weight percent and the 
oxypropylene content is from about 0 to about 25 weight percent, the total 
number of oxyethylene and oxypropylene units in M being from about 2 to 
about 15, 
N is an oxypropylene group or a mixture of oxyethylene and oxypropylene 
groups wherein the oxypropylene content is from about 75 to 100 weight 
percent and the oxyethylene content is from 0 to about 25 weight percent, 
the number of oxyethylene and oxypropylene groups in N being from about 2 
to about 10, wherein 
EQU [Z--M--Y--M] and [Z--N--Y--N] 
are linked together either in a random or an ordered manner, 
R is M or N, and 
a and b are integers from 2 to 20 in a ratio between 1:9 to 9:1. 
It is to be understood that the above formulae as used in the specification 
and claims are generalized formulae and do not represent only a single 
block of polyoxypropylene groups and a single block of polyoxyethylene 
groups but, on the contrary, the compounds of this invention may be either 
of a random block variety or an ordered block type which may have 
considerably more than two blocks. Random block surfactants are generally 
prepared by reacting, for example, a mixture of oxyethylene and 
oxypropylene polymers and copolymers with either formaldehyde or dialkyl 
carbonate. The reaction is continued, when a dialkyl carbonate is used, at 
a temperature of 150.degree. C. An alkanol is distilled off while the 
temperature is gradually raised to about 200.degree. C. If formaldehyde is 
used as the linking agent, the mixture of oxypropylene and oxyethylene 
polymers is reacted with formaldehyde and water is removed by azeotropic 
distillation with a solvent such as benzene at a temperature between 
75.degree. and 100.degree. C. Optionally, random block surfactants may be 
prepared by forming the linked blocks of oxypropylene and oxyethylene 
individually and then blending them together for a final linking process 
with either formaldehyde or a dialkyl carbonate. 
Ordered block surfactants are prepared by reacting an oxypropylene polymer 
and an oxyethylene polymer individually with either a dialkyl carbonate or 
formaldehyde to form a linked oxypropylene or oxyethylene copolymer block. 
These linked copolymer blocks are then blended together in the amounts 
required to achieve the desired balance of hydrophilic and hydrophobic 
units. This blend is then further subjected to a linking process, as 
described above, wherein either formaldehyde or a dialkyl carbonate were 
used as the linking agent. 
The time required for the above reactions is generally not a critical 
factor but will vary with the concentration of reactants and the reaction 
temperatures. Thus, the time can vary from about 15 minutes to about 10 
hours in each case. From an economic point of view, however, it is 
impractical to continue any reaction for more than ten hours. Generally, 
the reactions are completed within five hours. Thus it is possible to form 
a surfactant composed of low molecular weight hydrophilic and hydrophobic 
units coupled either through formal groups or carbonate groups as shown by 
the following formula: 
EQU H--M--Y--M--Z--N--Y--N--Z--M--Y--M--Z--N--Y--N--Z--M--Y--N--H 
and 
EQU H--N--Y--N--Z--N--Y--N--Z--M--Y--M--Z--M--Y--M--Z--N--Y--N--Z--N--Y--N--H 
where Y, M, N, and Z are as defined above. 
This unique structure of the formal or carbonate linked multi-block 
copolymers results in surfactants which are useful for a number of 
applications. They may be used as biodegradable or quasi-biodegradable 
surfactants. These molecules fragment into the individual polyoxyalkylene 
glycols either biologically or hydrolytically under either slightly acidic 
or basic conditions. They are useful as anti-foaming agents and as 
surfactants where very low foam is required. These surfactants may also be 
used in rewetting paper pulp for the manufacture of paper. They may be 
used as surfactants or lubricants in textile applications in which removal 
of the surfactant or lubricant is required before subsequent processing 
steps are carried out. Removal can be readily accomplished by passing the 
textile material through a slightly acidic or basic treating bath.

The following examples illustrate the invention. All parts are by weight 
unless otherwise stated. 
EXAMPLE 1 
Preparation of polycarbonate copolymer. 
A clean, dry, 1 liter distilling flask equipped with fractionating column 
and distillation head was charged with 250 grams of polyethylene glycol, 
molecular weight 400, 250 grams of polypropylene glycol, molecular weight 
435, 159 grams of diethyl carbonate and 0.5 gram of potassium carbonate. 
The mixture was heated to 150.degree. C. After allowing the temperature to 
remain at this point for thirty minutes, the pot temperature was gradually 
raised to 200.degree. C. At the same time ethanol was removed. The flask 
contents were cooled to 110.degree. C. The volatiles were then distilled 
off at a pot temperature of 150.degree. C. at 10 millimeters of mercury 
pressure. The weight of the product obtained was 538 grams. The vacuum 
strippings were found to be approximately 50 percent ethanol and 50 
percent diethyl carbonate. The amount of recovered ethanol corresponds to 
a coupling of eight polyethylene glycol and polypropylene glycol units 
corresponding to a molecular weight of approximately 3200. 
EXAMPLE 2 
A clean, dry, 1 liter distilling flask equipped with fractionating column 
and distillation head was charged with 300 grams of polyethylene glycol, 
molecular weight 600, 300 grams of polypropylene glycol, molecular weight 
800, 126 grams of diethyl carbonate, 0.6 gram of potassium carbonate and 1 
gram of 20 percent potassium hydroxide in methanol. The reaction was 
allowed to proceed as in Example 1. The amount of recovered volatiles was 
76 grams of ethanol and 22 grams of diethyl carbonate. The weight of 
product obtained was 627 grams. 
EXAMPLE 3 
Preparation of a polyformal copolymer. 
A clean, dry, 1 liter flask equipped with a stirrer, reflux condenser, Dean 
Starke water separator, thermometer and nitrogen inlet was charged with 
250 grams of polyethylene glycol, molecular weight 400, 250 grams of 
polypropylene glycol, molecular weight 434, 72 grams of paraformaldehyde, 
1.1 mls. of concentrated sulfuric acid and 200 mls. of benzene. The 
temperature of the mixture was raised from 25.degree. to 90.degree. C. and 
24.6 grams of water was removed by azeotropic distillation with benzene. 
The residual benzene was then removed by distillation at a pot temperature 
of 125.degree. C. at atmospheric pressure and the product was finally 
stripped at 120.degree. C. at 2 millimeters of mercury pressure. The 
amount of product obtained was 520 grams. 
EXAMPLE 4 
A clean, dry, 1 liter flask equipped with a stirrer, reflux condenser, Dean 
Starke water separator, thermometer and nitrogen inlet was charged with 
250 grams of polyethylene glycol, molecular weight 588 and 250 grams of 
polypropylene glycol, molecular weight 800, 24.6 grams of 
paraformaldehyde, 1 milliliter of concentrated sulfuric acid and 200 
milliliters of benzene. The temperature of the mixture was raised from 
25.degree. C. to 90.degree. C. and 14.4 grams of water was removed by 
azeotropic distillation with benzene. The residual benzene was then 
removed by distillation as described in Example 3. The product obtained 
weighed 517 grams. 
The Table illustrates the properties of the compounds obtained from the 
above Examples. 
TABLE 
______________________________________ 
Surfactant Properties 
Example 1 2 3 4 
______________________________________ 
Cloud Point, 1% Solution, .degree. C. 
45-49 28-31 46-50 63-69 
Surface Tension, 1% Solution, 
25.degree. C., dynes/cm 
37.1 35.1 41.7 38.4 
Draves Sink time, 3 g. hook, 
0.1% Solution, 25.degree. C., sec. 
44 52 276 62 
Dynamic Foam* 400 ml/min. 
at 77.degree. F. 
9/4 36/25 40/4 20/12 
at 120.degree. F. 
0/0 25/6 25/6 65/16 
______________________________________ 
*The procedure and apparatus used for the dynamic foam measurements may b 
found in "Soap and Chemical Specialties" 37, 55, April 1961. 
This Table illustrates both the excellent wettability of these surfactant 
and their low foaming properties.