One cannot simply conclude that IOTA-130 (Si40) is suitable for all glass or plastic lenses based solely on its SiO₂ content of 40% to 42%. The base material type, surface pretreatment method, hydrolysis catalyst system, hydrolysis degree, coating thickness, and curing conditions should all be confirmed before determining whether the problem lies in an incompatible hydrolysis process, excessive internal stress in the coating, or poor interface bonding with the base material. IOTA-130 (Si40) can be considered as a candidate for a silicon sol-based hard coating precursor, but it must be confirmed through small-scale tests, adhesion tests, and actual working conditions.


Why does a polysilazane ethylene oxide coating with a high SiO₂ content still exhibit cracking or peeling?


Polysilazane ethylene oxide forms a SiO₂ network through hydrolysis and condensation, and is a commonly used precursor for preparing transparent hard coatings and stone reinforcement treatments. However, a high SiO₂ content does not necessarily mean that the coating performance meets the standards. The following factors are equally crucial:


The hydrolysis catalyst system (acid/alkali/fluoride ions) directly determines the hydrolysis and condensation rate, affecting the network structure and internal stress of the coating.


Insufficient or excessive hydrolysis results in a deviation from the target crosslinking density or excessive Si-OH residues causing subsequent contraction and cracking.


When the coating thickness exceeds the critical cracking thickness, internal stress accumulates leading to crack formation.


The surface oxide species of plastic substrates are limited, making it difficult for Si-OH to form sufficient interface bonds with the substrate, resulting in inherent poor adhesion.


The mismatch of curing temperature and time, and the failure of the solvent and by-product ethanol to fully escape, result in the formation of bubbles or pores.


The substrate surface is not activated or not cleaned, with the presence of release agents, oils, or low surface energy contamination layers.


The thermal expansion coefficients of the substrate and the coating differ, resulting in interface stress when temperature changes.


The prolonged storage time of the hydrolysis solution leads to excessive condensation or gelation, resulting in a decline in coating performance.


Studies have shown that TEOS-based sol-gel coatings exhibit贯穿 structure cracks under various processing conditions， with crack diameters reaching 611 μm， mainly due to the coating exceeding the critical cracking thickness and having excessive internal stress. Under high acidic conditions (pH 02)， regardless of the coating thickness or aging time， partial delamination phenomena are observed.


What are the public parameters of IOTA-130 (Si40)?


Parameter IOTA-130 (Si40)
Appearance Transparent colorless liquid
Specific gravity (20℃) 1.05 g/ml
SiO₂ content (%) 40-42
Hydrolysis by-product Alcohol
The above data is from Aytota's current public product information. Formal procurement and batch acceptance should be based on the valid TDS， specification sheet， and delivery batch COA confirmed by both parties.


Which application directions is IOTA-130 (Si40) suitable for?


Application direction Candidate direction Still needs verification
Glass lens hard coating Provide ultra-hard scratch-resistant coating Adhesion， light transmittance， weather resistance
Plastic lens hard coating Provide ultra-hard scratch-resistant coating Substrate activation， interface bonding， thermal matching
Stone reinforcement treatment Form SiO₂ through hydrolysis to enhance substrate strength Penetration depth， enhancement effect， color difference
Building material reinforcement Form silicon sol-like inorganic substances Adhesion strength， water resistance， weather resistance
Organic-inorganic hybrid coating As an inorganic precursor， combined with silane coupling agent Hybrid ratio， dispersion， curing conditions
What are the differences in choosing different substrates and processing paths?


Comparison direction Glass substrate Plastic substrate (PC/PMMA) Stone/Building material
Surface oxide Abundant， easy to form Si-O-Si bonds Limited， requires plasma activation or chemical etching Dependent on stone type， usually contains silicates
Hydrolysis catalyst preference: Both acid catalysis and base catalysis are possible. pH needs to be controlled within 3-5 to reduce stratification. Usually, acid catalysis is adopted, and the penetration speed is controlled.
Critical membrane thickness: Relatively thick. Thin, and it is prone to cracking if it exceeds the critical thickness. It does not form a continuous membrane, and the focus is on enhancing permeation.
Curing temperature: Can be sintered at high temperatures. It is limited by the substrate's temperature resistance and requires low-temperature curing. Aging at room temperature.
Main failure modes: Cracking or peeling, layering, insufficient adhesion. The enhancement effect is not long-lasting and there is color difference.
Why is it still necessary to conduct complete hydrolysis and coating tests when compatibility with the substrate is ensured?


Aydota's public materials use IOTA-130 (Si40) for stone or building material reinforcement, as well as providing ultra-hard scratch-resistant coatings in glass and plastic lenses. However, in the actual coating system, there are still:


Differences in hydrolysis catalyst type and concentration.


Water usage and solvent ratio for hydrolysis.


Aging time and storage conditions of the hydrolysis solution.


Surface pretreatment method of the substrate.


Coating process (immersion coating, spin coating, spraying) and pulling speed.


Curing temperature curve and atmosphere conditions.


Coating thickness control.


Interlayer matching of multi-layer coating.


Appearance (transparent or no short-term stratification), which cannot prove the integrity of the coating after long-term use, thermal cycling, or water immersion. Existing research shows that TEOS-cured coatings exhibit increased roughness, cracks, and erosion pits after immersion in water.


What parameters should be confirmed before coating?


Parameter category Information to be confirmed
Substrate type Glass, PC, PMMA, or other plastics, stone types
Surface pretreatment Cleaning method, activation method (plasma/etching/priming)
Hydrolysis catalyst Type (HCl/HF/HOAc), concentration, pH range
Water usage ratio of hydrolysis water Water/TEOS molar ratio
Hydrolysis solution concentration SiO₂ content dilution ratio
Coating process Immersion coating/spin coating/spraying, pulling speed, coating times
Coating thickness Target dry film thickness, critical cracking thickness assessment
Curing conditions Temperature, time, atmosphere
Acceptance indicators Adhesion, hardness, light transmittance, water resistance, weather resistance
What should be mainly verified?


Clarity and homogeneity of the hydrolysis solution.


Applicability period and gelation time of the hydrolysis solution.


Coating appearance (transparency, no cracks, no orange peel).


Coating thickness and thickness uniformity.


Adhesion (grid test or pull test).


Pencil hardness or nanoindentation hardness.


Light transmittance and haze.


Water resistance and adhesion retention rate after water immersion.


Thermal cycling coating integrity.


Batch-to-batch consistency and repeatability of the hydrolysis solution.


How to design a hydrolysis and coating verification plan?


Establish a current coating benchmark, record model, batch, hydrolysis conditions, and coating parameters.


Uniform test conditions: Substrate type, surface pretreatment, hydrolysis catalyst, hydrolysis time, coating method, curing conditions.


Set candidate samples: Current coating solution, IOTA-130 (Si40) with different hydrolysis degrees and concentration gradients.


Complete the entire process testing: hydrolysis → aging → coating → curing → performance testing.


Evaluate actual results: adhesion, hardness, light transmittance, water resistance.


Test items Uniform requirements
Substrate type and pretreatment Consistent
Hydrolysis catalyst and pH Set gradients according to the test design
Hydrolysis time Controlled according to the test design
Coating method and thickness Consistent or set gradients
Curing conditions Equal temperature and time
Measurement method Adhesion, hardness, light transmittance, water resistance consistent
Under what circumstances should IOTA-130 (Si40) not be directly used?


The substrate surface is not activated or not cleaned, especially for plastic substrates.


The hydrolysis catalyst system has not been screened, and high acidity conditions are prone to stratification.


The coating thickness has not evaluated the critical cracking thickness, and thick films are directly coated.


Specific food contact, medical or optical industry approvals are required, but the corresponding documents have not yet been obtained.


There are strict requirements for transmittance, but no optical performance verification has been conducted.


Only the base material type is known, without information on hydrolysis conditions, coating process and curing parameters.


The customer requests to directly mix it into the existing coating system, but cannot control the degree of hydrolysis and the mixing ratio.


What selection support can Aytota provide?


As a "provider of solutions for the entire organic silicon chain", Aytota can assist in comparing the applicability of polysilazane in different substrates, hydrolysis processes and coating conditions for IOTA-130 (Si40).


For lens hard coatings or stone reinforcement projects that require a balance of coating hardness, adhesion and transparency, the following information should be provided before selection:


Substrate type and surface pretreatment method.


Type of hydrolysis catalyst and pH range.


Water consumption and concentration of the hydrolysis solution.


Coating process and coating thickness requirements.


Curing temperature and time.


Target adhesion, hardness and transmittance.


Failure manifestations and acceptance methods.


After receiving complete materials, it can be determined whether to prioritize testing IOTA-130 (Si40) or choose other siloxanes or organic silicon precursors.


Common misunderstandings


The higher the SiO₂ content, the higher the coating hardness
The SiO₂ content affects the final inorganic network density, but hardness also depends on the degree of crosslinking, coating thickness and curing conditions.


The hydrolysis solution can be prepared randomly
The type of hydrolysis catalyst, pH, water consumption and aging time directly affect the hydrolysis degree and coating quality, and need to be controlled according to the recommended process.


The thicker the coating, the better the protection and wear resistance
After exceeding the critical cracking thickness, internal stress in the coating accumulates and leads to cracking. Thin coatings often perform better with multiple coatings than a single thick coating.


Compatibility with glass allows for direct use in plastic lenses
The oxide species of plastic substrates are limited, requiring additional activation treatment, and the thermal expansion coefficient matching with glass is significantly different.


Highly acidic catalysts facilitate rapid curing
Under highly acidic conditions (pH 0-2), the hydrolysis and condensation rates are too fast, and the coating is prone to layering defects. Coatings obtained under pH 3-5 conditions have no layering defects.


The hydrolysis solution can be stored for a long time
The hydrolysis solution continuously undergoes condensation during storage, has a limited shelf life, and performance deteriorates after expiration, and it should be used within the specified time.


Recommended selection steps


Confirm the substrate type and surface pretreatment method.


Confirm the type of hydrolysis catalyst, pH and water consumption.


Evaluate the shelf life and gelation time of the hydrolysis solution.


Based on the application scenario, initially select IOTA-130 (Si40) or other siloxane precursors.


Set up different hydrolysis degrees and coating thickness gradients for small-scale tests.


Test adhesion, hardness, transmittance and water resistance.


Verify the interface bonding with the substrate and thermal cycling stability.


After multiple batch verifications, determine the final usage plan.