Alkyl hydroxyalkyl cellulose ethers, methods of making, and use in cements and mortars

A method comprising:

• a) mixing an alkaline solution comprising an alkali metal hydroxide with cellulose and an alkyl halogenide at a temperature of at least 10° C. to form a first reaction mixture comprising alkali cellulose, water, and the alkyl halogenide, wherein the alkali metal hydroxide is present in an amount of from about 2.92 to about 5.00 equivalents per anhydroglucose unit of the cellulose;
• b) adjusting the temperature of the first reaction mixture to be within a range of from about 60 to about 110° C. resulting in a reaction of a portion of the alkyl halogenide with the alkali cellulose forming a second reaction mixture comprising alkyl cellulose ether and unreacted alkyl halogenide, wherein the second reaction mixture is maintained at a temperature within the range of from about 60 to about 110° C. prior to the addition of an alkylene oxide;
• c) cooling the second reaction mixture to a temperature in a range of from about 25 to about 80° C. to form a third reaction mixture;
• d) adding the alkylene oxide to the third reaction mixture from step c) to form a fourth reaction mixture;
• e) adjusting a temperature of the fourth reaction mixture from step d) to be in a range of from about 80 to about 110° C. and reacting at least a portion of the alkyl cellulose ether in the fourth reaction mixture with:
• i) at least a portion of the alkylene oxide, and ii) at least a portion of the unreacted alkyl halogenide, thereby forming a fifth reaction mixture comprising an alkyl hydroxyalkyl cellulose ether having a methyl D.S. value of from about 1.40 to about 2.10, and a hydroxyethyl M.S. value of from about 0.05 to about 0.4;
• and
• f) recovering the alkyl hydroxyalkyl cellulose ether from the fifth reaction mixture from step e).