New selective method for quantification of organosilanol groups in silicone pre-elastomers

Area of Science:

• Materials Science
• Polymer Chemistry
• Analytical Chemistry

Background:

• Silicone elastomers for drug delivery utilize fumed silica reinforcement, which contains reactive silanol groups.
• These silanol groups can cause undesirable stiffening (creep hardening) in uncured pre-elastomers.
• Deactivation of silanol groups typically involves mixing with organosilanols at elevated temperatures.

Purpose of the Study:

• To develop a selective method for quantifying nonbonded organosilanols in silicone pre-elastomers.
• To address the limitations of traditional testing methods that cannot differentiate between inorganic and organosilanols.

Main Methods:

• A novel derivatization technique using dimethylphenylchlorosilane and tetramethyldiphenylsilazane was employed.
• Derivatized organosilanols were quantified using liquid chromatography with a size exclusion column and UV detection.
• The method was validated for selectivity against common interfering groups in medical-grade pre-elastomers.

Main Results:

• The developed method selectively quantifies organosilanols without interference from inorganic silanols, water, vinyls, or hydrides.
• Results from the selective method showed good agreement with nonselective Karl Fischer titration for short-chain silanols.
• This analytical advancement allows for precise control over the deactivation process.

Conclusions:

• A selective and reliable analytical method for organosilanols in silicone pre-elastomers has been established.
• This method is essential for quality control in the manufacturing of silicone-based drug delivery systems.
• Accurate quantification of organosilanols ensures optimal material properties and prevents creep hardening.