Glass Vial Modification: Silanes & Surface Treatment
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Questions and Answers

Why is piranha solution used to pretreat glass vials before modification with silane reagents?

  • To increase the hydroxyl content on the glass surface, improving silane reagent modification. (correct)
  • To reduce the impact of ion exchange during the staining process.
  • To decrease the hydroxyl content on the glass surface.
  • To remove any existing coatings on the glass surface.

What observation indicates successful modification of the inner surface of glass vials after staining with methylene blue solution?

  • Speckled staining pattern.
  • A darker blue color, signifying severe corrosion.
  • A lighter or almost unobservable staining, indicating reduced corrosion. (correct)
  • An unchanged blue color compared to unmodified vials.

What is the key characteristic of BADMSCP that allows it to modify hydroxyl groups on glass surfaces effectively?

  • The presence of a silicon-nitrogen (Si-N) moiety that undergoes a ring-opening reaction. (correct)
  • Its ability to react only at high temperatures.
  • The presence of methyl groups that prevent corrosion.
  • Its complex molecular structure.

Why is the reaction between BADMSCP and the glass surface referred to as a 'ring-opening click' reaction?

<p>Because of its simplicity, high yield, wide applicability, absence of by-products, and use of easily removable solvents. (C)</p> Signup and view all the answers

How does the -OMe group in the BADMSCP structure contribute to the modification process?

<p>It is readily hydrolyzed to -OH, which further reacts with -OH groups on the glass surface, strengthening the bond. (C)</p> Signup and view all the answers

What conditions are necessary for HMDS to effectively modify the inner surface of glass vials, according to the information?

<p>Higher temperatures and longer reaction times. (C)</p> Signup and view all the answers

In the context of modifying glass vials, what does a lighter staining observed after methylene blue staining indicate?

<p>The surface modification improved, reducing corrosion. (C)</p> Signup and view all the answers

What is the primary effect of HMDS modification on silica surfaces?

<p>Converts the surface from hydrophilic to hydrophobic. (D)</p> Signup and view all the answers

Why is HMDS considered advantageous despite its lower reactivity compared to BADMSCP?

<p>It offers a more cost-effective solution. (A)</p> Signup and view all the answers

Considering the information provided, what is the primary advantage of using BADMSCP over HMDS for modifying glass vials?

<p>BADMSCP can efficiently complete the modification process at room temperature without a catalyst. (A)</p> Signup and view all the answers

What do the FT-IR results reveal about the silanisation treatment of the vials?

<p>It successfully grafts hydrophobic functional groups onto the glass surface. (C)</p> Signup and view all the answers

What is the significance of observing peaks at approximately 1460 cm-1 and 3000 cm-1 in the FT-IR spectra of the modified vials?

<p>They suggest the bending and stretching vibrations of C-H bonds, respectively. (D)</p> Signup and view all the answers

Based on the text, what is the main purpose of modifying glass vials with HMDS?

<p>To improve the hydrophobicity and hydrolytic resistance of the glass surface. (D)</p> Signup and view all the answers

Why might FT-IR not detect significant changes in the molecular structure of the modified glass vials?

<p>Because the modified layer is only a single molecular layer and difficult to characterize. (A)</p> Signup and view all the answers

What does the experiment using methylene blue solution and HMDS-modified vials demonstrate?

<p>HMDS modification effectively prevents staining, indicating enhanced hydrophobicity. (B)</p> Signup and view all the answers

Which of these characteristics is NOT a beneficial outcome of the surface modification engineering described?

<p>Increased operational costs due to specific equipment. (D)</p> Signup and view all the answers

FE-SEM images of vial surfaces before and after modification with silanising reagents show:

<p>Subtle changes in the chemical composition without significant alterations to the overall glass nature. (B)</p> Signup and view all the answers

What observation indicates the hydrolytic resistance of vials modified with BADMSCP has improved?

<p>A minimal elevation of pH value, nearly indistinguishable from high-purity water. (D)</p> Signup and view all the answers

How does surface modification with silazanes affect the macroscopic appearance of vials?

<p>The appearance of vials remains unaffected macroscopically. (A)</p> Signup and view all the answers

What would be the most likely reason no distinguishable modified layer can be observed in cross-sections of vials post-modification?

<p>The modification only affects the chemical composition of the surface at a molecular level. (D)</p> Signup and view all the answers

What happens to the pH value of water in unmodified vials after a hydrolytic resistance test, and why?

<p>It increases due to the release of metal ions from the glass. (A)</p> Signup and view all the answers

If a vial is treated with BADMSCP and shows a pH value of 7.2 after a hydrolytic resistance test, what can be inferred?

<p>The concentration of BADMSCP was high enough to almost completely prevent metal ion release. (D)</p> Signup and view all the answers

Based on the observations, which property of the vials is most directly enhanced by the silazane modification?

<p>Hydrolytic resistance (D)</p> Signup and view all the answers

In the hydrolytic resistance experiments, what serves as a control to assess the effect of the surface modification?

<p>Vials without any surface modification. (B)</p> Signup and view all the answers

What is the primary mechanism by which silazane surface engineering enhances the hydrolytic resistance of glass vials?

<p>By increasing the contact angle, creating a hydrophobic barrier that prevents water diffusion and ion exchange. (A)</p> Signup and view all the answers

What impact does modifying the inner surface of glass vials with silazanes have on the water contact angle, and what does this change signify?

<p>The water contact angle increases, indicating enhanced hydrophobicity and improved water resistance. (C)</p> Signup and view all the answers

What is the role of organic hydrophobic groups, such as -(CH3)3, in enhancing the hydrolytic resistance of glass surfaces modified with silazanes?

<p>They replace -OH groups on the glass surface, creating a barrier that shields the glass from water and prevents ion exchange. (D)</p> Signup and view all the answers

What is the significance of preventing ion exchange between H+ and metal ions (Ca2+, Na+, Mg2+, K+) in the glass's inner layers when improving hydrolytic resistance?

<p>It maintains the glass's chemical integrity by preventing the weakening of the Si-O-Si backbone and selective dissolution, preserving its structural integrity. (B)</p> Signup and view all the answers

How does silazane surface engineering address the issue of surface blurring or the formation of small pits on glass surfaces with low contact angles?

<p>By increasing the contact angle, creating a hydrophobic surface that resists water-induced damage. (C)</p> Signup and view all the answers

Considering the application of silazane surface engineering with BADMSCP and HMDS, what is the key advantage of performing this modification under mild and catalyst-free conditions?

<p>It simplifies the modification process, reduces costs, and minimizes potential side reactions or damage to the glass vial. (D)</p> Signup and view all the answers

What is the primary reason for treating the inner surface of vials with silazane reagents?

<p>To modify the surface from hydrophilic to hydrophobic. (A)</p> Signup and view all the answers

If a glass vial exhibits a water contact angle of 65°, what can be inferred about its surface properties and hydrolytic resistance based on the information provided?

<p>It has a relatively low hydrophobicity and poor water resistance, making it susceptible to water-induced damage. (B)</p> Signup and view all the answers

In the context of improving the hydrolytic resistance of glass vials, what is the function of the Si-O-Si backbone, and why is it important to protect it?

<p>It provides structural support and chemical integrity to the glass, and its degradation leads to weakening and dissolution of the glass. (A)</p> Signup and view all the answers

Why is MM (a solvent) used during the surface modification process?

<p>To provide a stable medium for the reaction. (B)</p> Signup and view all the answers

What conclusion can be drawn from the observation that the water contact angle of the surface-modified vials remains stable after extraction with n-heptane?

<p>The silazanes used are chemically grafted to the glass surface, creating a strong chemical bond. (D)</p> Signup and view all the answers

Based on the text, what is the effect of piranha solution on the inner surface of blank vials?

<p>It increases the number of hydroxyl groups present on the inner surface. (A)</p> Signup and view all the answers

What is the approximate water contact angle of the inner surface of the blank vials before any surface modification?

<p>65° (B)</p> Signup and view all the answers

For HMDS, after at least 80 minutes, what is relationship between the reaction temperature and the water contact angle?

<p>The effect of temperature will be much greater than the effect of time. (A)</p> Signup and view all the answers

Which statement is true regarding the impact of surface engineering on vial transparency and light transmittance?

<p>The transparency and light transmittance of vials are not significantly changed by surface engineering. (A)</p> Signup and view all the answers

What does SEM analysis reveal about vials modified with HMDS and BADMSCP after a hydrothermal aging test?

<p>The inner surface of the vials remains flat, with no glass delamination or dehiscence. (A)</p> Signup and view all the answers

How does the chemical grafting of silazanes to the vial surface compare to the use of silicone oil treatments, as mentioned in the text?

<p>Silicone oil can be detached by organic solvent extraction, unlike the silazanes used in this study. (A)</p> Signup and view all the answers

What is the primary benefit of modifying the inner surface of vials with HMDS and BADMSCP?

<p>It significantly improves the barrier properties of the inner surface. (D)</p> Signup and view all the answers

What is a key advantage of using HMDS and BADMSCP to modify the inner surface of vials, besides improved barrier properties?

<p>It does not affect the appearance of the vials. (D)</p> Signup and view all the answers

In the context of pharmaceutical packaging, what is the significance of preventing glass delamination?

<p>It prevents the release of glass particles into the drug product, maintaining its purity. (C)</p> Signup and view all the answers

What is the most likely reason for using a hydrothermal aging test on pharmaceutical vials?

<p>To accelerate the degradation processes and predict long-term stability. (D)</p> Signup and view all the answers

If a pharmaceutical vial shows evidence of 'dehiscence' after testing, what has occurred?

<p>The vial has shown signs of surface cracking or splitting. (C)</p> Signup and view all the answers

How might improving the 'barrier properties' of a vial’s inner surface benefit a pharmaceutical product stored within?

<p>By preventing interaction between the drug and the glass, thus maintaining drug stability. (A)</p> Signup and view all the answers

A study compares modified and unmodified vials, and finds only the unmodified vials show glass delamination. What can be inferred from this result?

<p>The modification enhances the glass's resistance to corrosive attack. (D)</p> Signup and view all the answers

Flashcards

What is HMDS?

A commonly used surface modifier, often used in the surface modification of silica.

HMDS Reaction Mechanism

HMDS reacts with -OH groups on the surface, bonding -Si(CH3)3 onto SiO2.

HMDS Effect on Silica Surface

Transforms the surface of silica from hydrophilic to hydrophobic.

HMDS Surface Modification

A method to modify surfaces that doesn't require catalyst or high temperatures.

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1460 cm-1 peak in FT-IR

Bending vibration of C-H bonds, seen in FT-IR analysis after silanization.

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3000 cm-1 peak in FT-IR

Stretching vibration of C-H bonds, indicating successful grafting.

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C-H peaks in FT-IR after modification?

Verifies that BADMSCP and HMDS were successfully attached to the surface.

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Purpose of hydrophobic functionalization?

Grafting hydrophobic groups onto the glass surface to increase water resistance.

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Methylene Blue Staining

A method to assess glass corrosion by observing blue staining after applying methylene blue solution. Darker color indicates more severe corrosion.

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BADMSCP Modification

BADMSCP modifies glass via a ring-opening reaction with surface hydroxyl groups, creating a strong bond.

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"Ring-Opening Click" Reaction

A reaction where a cyclic compound opens and binds to a surface without byproducts.

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Piranha Solution Etching

Pre-treatment of glass with piranha solution increases hydroxyl groups on the surface, improving silane reagent binding.

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BADMSCP Structure

BADMSCP has a silicon-nitrogen (Si-N) moiety which facilitates a facile ring-opening reaction to modify hydroxyl groups.

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BADMSCP Hydrolysis

Hydrolysis of -OMe groups in BADMSCP forms -OH groups, which further react with -OH groups on the glass surface.

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HMDS Modification

HMDS requires higher temperatures to modify glass effectively, particularly without a catalyst.

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HMDS Temperature/Time Effect

Increasing temperature and reaction time enhances the effectiveness of HMDS modification on glass surfaces.

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Surface Engineering

Process of modifying a surface's properties using chemical or physical techniques.

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Silazanes in Surface Modification

Silazanes are used to change a surface from water-attracting (hydrophilic) to water-repelling (hydrophobic).

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Hydrophilic Surface

Surfaces that attract water, having a water contact angle less than 90 degrees.

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Hydrophobic Surface

Surfaces that repel water, having a water contact angle greater than 90 degrees.

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Water Contact Angle

A measure of how much a liquid droplet spreads out on a surface.

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Piranha Solution's Effect

Piranha solution cleans surfaces and adds hydroxyl groups (OH), making them more hydrophilic.

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HMDS Reaction Temperature

HMDS requires a certain temperature to react and effectively modify a surface due to the strength of its Si-N bond.

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Silazane Grafting

Silazanes chemically bond/graft to the glass surface creating a strong chemical bond with relatively high chemical stability.

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FE-SEM

Images taken with a Field Emission Scanning Electron Microscope to observe surface details.

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Surface Modification Impact

BADMSCP and HMDS modify only the surface chemistry, not the physical structure.

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Hydrolytic Resistance Tests

Tests that assess how well materials resist degradation in hot water.

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pH Increase in Vials

The pH of water increases due to metal ions being released from the glass.

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Silazane Effect on pH

Silazanes improve hydrolytic resistance, preventing pH increase.

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BADMSCP Concentration Effect

Higher BADMSCP concentration leads to better hydrolytic resistance.

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Sample B-5 Significance

Sample B-5 exhibits a minimum pH change, indicating high hydrolytic resistance.

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Silazane Surface Engineering

Applying silazanes to enhance a vial's resistance to water damage.

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High Contact Angle Benefit

High contact angles indicate hydrophobicity and prevent water-induced damage.

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Hydrophobic Group Action

Hydrophobic groups replace -OH groups, blocking water diffusion and ion exchange.

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Protecting the Glass Network

Shielding water and preventing ion exchange (Ca2+, Na+, etc.) to maintain glass integrity.

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Result of Silazane Modification

Leads to remarkable enhancement of the hydrolytic resistance of vials.

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Silazanes (BADMSCP & HMDS)

Can modify pharmaceutical glass vials under mild, catalyst-free conditions.

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Contact Angle Improvement

Increases from 65° to 101° after modification, which shows good hydrolytic resistance.

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Hydrothermal Aging Test Goal

Checking hydrolytic resistance by aging vials in hot, pressurized water.

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SEM Analysis

Analytical technique using electrons to produce magnified images of a sample's surface.

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Hydrothermal Aging Test

Aging vials under high temperature and pressure in water to test their stability.

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Glass Delamination

The separation of layers of glass, creating flakes in a solution.

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Glass Dehiscence

The cracking or splitting of a material's surface.

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Barrier Properties

Improving a material's ability to prevent substances from passing through it.

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Vial Surface Modification

Addition of HMDS and BADMSCP to glass vials to improve their properties.

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SEM Analysis Result

Modified vials showed no visible damage after aging tests.

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Silane Improvement

Silanes improve the ability of vials to resist degradation.

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Study Notes

  • The study focuses on improving the chemical durability of glass vials by grafting silazanes onto the inner surface under mild conditions
  • This is achieved through surface engineering.

Materials Used and Grafting Process

  • Two silazanes are used: n-n-butyl-azido-2,2-dimethoxysilazane (BADMACP) and hexamethyldisilazane (HMDS)
  • These are grafted onto the inner vial surface through O-Si bonds, creating a hydrolysis-resistant surface
  • Colorimetric staining, FT-IR, and water contact angle (WCA) measurements confirm successful chemical modification
  • WCA increased from 65° in unmodified vials to over 100° after modification

Hydrolytic Resistance and Barrier Properties

  • Hydrothermal aging tests showed a significant reduction in metal ion precipitation
  • This surface modification enhances the barrier properties of vials without altering their appearance or transmittance
  • The inner surface of vials can be modified through chemical grafting with silazanes in a mild, catalyst-free process
  • Modification elevates the water contact angle (WCA) on the inner vial surface from 65° to above 100°

Hydrolysis Resistance

  • Hydrothermal aging tests revealed that the surface modification enhances hydrolysis resistance by over 86%
  • The surface engineering process does not compromise the light transmittance of vials

Silazane Grafting

  • Two silazanes are used to modify the inner surfaces of vials under mild conditions: BADMSCP and HMDS.
  • Silazanes react with -OH surface groups via Si-N bonds, resulting in a stable, hydrolysis-resistant surface.
  • Chemical modification confirmed through various methods, including colorimetric staining and FT-IR.
  • Water Contact Angle (WCA increased from 65° to >100°, improving the glass's hydrolytic resistance.
  • Hydrothermal aging tests reduced metal ion precipitation, lowering the risk of glass delamination.
  • Surface modification with HMDS/BADMSCP improves the inner surface's barrier properties without affecting the vial's appearance/transmittance.

Introduction

  • Glass is a common pharmaceutical packaging material, mainly for its transparency and temperature resistance
  • Growing drug complexity challenges glass's chemical durability
  • Injectable drugs in aqueous solutions require hydrolytic resistance
  • Glass delamination is a primary concern relating to chemical resistance which results in glass erosion
  • Consists of water diffusing into the glass and exchanged H+ ions -Dissolution of the silicate backbone of the glass
  • Problems due to hydrolytic resistance leads to drugs adhering to the wall

Solutions

  • The application of a silicone oil aims to transform the hydrophilic glass surface to hydrophobic
  • Surface engineering modifies inner vial surfaces under mild conditions with Si-N bonds
  • Organosilicon biocompatibility enhances the surface energy
  • Silazanes act as hydrophobic modifiers

Materials and Methods

  • Twenty-milliliter vials were procured from Schott.
  • The inner surface of the vials are etched with piranha solution eliminating impurities and enhancing the surface of the -OH content
  • A silazane mixture evenly coats the inside of the vial.
    • Each 20 mL vial receives a spray of 200 µL of silazane solution.

Experimental Conditions

  • Specific reaction conditions are shown in Table 1.

    • temperature /°C
      • BADMSCP: 25
      • HMDS: 120, 150, 180
    • time/min
      • BADMSCP: 120
      • HMDS: 40, 80, 120, 180
    • solvent
      • BADMSCP MM
      • HMDS MM
    • ratio to solvent
      • BADMSCP 1:5, 2:5, 3:5, 4:5, 5:5
      • HMDS 100%
    • spraying volume/µL
      • BADMSCP 200
      • HMDS 200

  • Throughout the staining experiments the homogeneity of grafting is sustained

  • Changes in color determine the surface modification's succes

    • A colorless staining ensures a successful ion exchange between the glass and the methylene blue is weak.

Additional Considerations

  • Hydrothermal aging and hydrolytic resistance tests are done according to the the United States Pharmacopeia (USP) and the European Pharmacopeia guidelines
  • Ultrasonic cleaning ensures precise rinsing and ultrapure water fills the vials
  • A cyclic silazane BADMSCP and a linear silazane HMDS were selected for surface modification.

Results and Discussion

  • Optimal reaction conditions produce high-quality modified vials using temperature, solvents and durations
  • BADMSCP vials use methylene blue to stain to see the comparison of the unmodified vials.
  • The blue color shows corrosion results due to ion exchange with the blue -Higher temperatures are necessary to modify HMDS, a catalyst -HMDS is commonly reported to modify silica. It reacts with the -OH groups on the silica surface to permit HMDS bonding to SiO2
    • Transforms the silica surface from hydrophillic resistant to hydrophobic (Si-OH) -HMDS as a low cost application in the silica is very informative in research
  • Can modify the vial's surface for the water contact angle for silazanes
  • After hydrothermal aging tests, vials showed no differences in the appearance the test's result prior

Concluding Remarks

  • Modification of the inner vial surface maintains its flat sleek look using HADMSCP/HDMS w/out impacting the appearance of the vials

  • The two silazanes, BADMSCP and HDMS were successful at using modifying the material surface when employing the surface engineering

  • Silazanes are chemically grafted with organic solvent

    • Creates a strong chemical bond.

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Applied Surface Science: Grafting Silazanes to Improve Vial Durability - PDF

Description

Piranha solution cleans glass vials before silane modification. Methylene blue staining indicates successful surface changes. BADMSCP modifies hydroxyl groups via ring-opening. HMDS provides an alternative method.

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