Polymer Synthesis Discussion Examples | How to Interpret Polymerization Conversion, Yield, and Side Reactions

What Is a Nylon Synthesis Experiment?

Nylon is a polyamide polymer containing amide bonds in its main chain.
In student experiments, methods in which a diamine and a dicarboxylic acid chloride or similar compounds are reacted to synthesize nylon are commonly used.
Through the reaction, monomers are continuously linked together and long polymer chains are formed.

A characteristic of nylon synthesis experiments is that the reaction is easy to observe visually.
A thin film may form at the interface between two liquid phases, and by pulling this film upward, a thread-like product may be obtained.
This observation indicates that a polymer is formed at the interface and grows as a continuous film.

Main Items to Include in the Results

In the results of a nylon synthesis experiment, organize the monomers used, solvents, condition of the interface, appearance of the product, product amount, yield, condition of the film, ease of pulling out the thread, and the state after washing and drying.
The appearance and texture of the product also provide clues for discussing the properties of the film and the state of polymer formation.

Main Items to Include in the Results

• Type of diamine used
• Type of dicarboxylic acid chloride or similar compound used
• Type of solvent
• Condition of the aqueous and organic layers
• Whether a film formed at the interface
• Whether the product could be pulled out as a thread
• Color of the product
• Shape of the product
• Thickness and uniformity of the film
• Strength and ease of breakage of the thread
• Condition after washing
• Mass after drying
• Yield
• Causes of low or high yield
• Sources of error and points for improvement

Reference Experimental Values and Analysis Examples for Nylon Synthesis

Here, reference experimental values are organized for discussing product amount, yield, film and thread properties, and the effects of reaction conditions, washing conditions, and drying conditions in nylon synthesis by interfacial polymerization.

In interfacial polymerization, a diamine in the aqueous layer reacts with a dicarboxylic acid chloride in the organic layer at the interface, producing nylon, which is a polyamide.
Because the reaction proceeds at the interface, the product amount and film properties vary depending on solution concentration, interfacial area, pulling speed, stirring, washing, and drying conditions.

Reference Experimental Conditions

Phenomena Observed in Interfacial Polymerization

Reaction and Concept of Theoretical Yield

Nylon 6,10 is a polyamide formed by condensation of hexamethylenediamine and sebacoyl chloride.
In the reaction, amide bonds are formed and hydrogen chloride is produced as a by-product.

For simplicity, it is assumed that 1 mol of diamine and 1 mol of dicarboxylic acid chloride react to form 1 mol of repeating units.

Under these conditions, sebacoyl chloride is the limiting reagent because its amount of substance is smaller.
Therefore, theoretically, 0.0030 mol of nylon repeating units can be produced.

Example Calculation of Theoretical Yield and Yield

The calculation is performed using 282 g/mol as the formula mass of the repeating unit of nylon 6,10.

Theoretical yield = Amount of limiting reagent × Formula mass of repeating unit

Theoretical yield = 0.0030 mol × 282 g/mol = 0.846 g

If the mass of the dried product is 0.520 g, the yield is determined as follows.

Yield (%) = Actual yield ÷ Theoretical yield × 100

Yield = 0.520 ÷ 0.846 × 100 = 61.5%

In this reference example, the nylon yield is 61.5%.

Example Measurements of Product Mass and Yield

Sample D appears to have a high yield, but if water or solvent remains in the product, the measured mass becomes larger than the actual value.
To evaluate the yield, it is necessary to confirm whether washing and drying were sufficient.

Changes in Product Mass With Drying Time

If water or solvent remains in the product, the measured mass changes with drying time.
A reference example of mass changes with drying time is shown below.

If the mass before drying is used, the yield may exceed 100%.
This is because the product contains water or solvent in addition to the product itself, so the constant mass after drying should be used to calculate the yield.

Effects of Different Washing Conditions

Nylon obtained by interfacial polymerization may contain unreacted substances, salts, acids, and solvents.
Differences in the properties of products obtained under different washing conditions are shown below.

Sufficient washing may decrease the apparent product amount because impurities and residual solvent are removed.
Not only the yield but also the purity and properties of the product should be evaluated.

Differences in Film Formation Depending on Concentration Conditions

If the reactant concentrations are too low, the film becomes thin and easily broken, whereas if the concentrations are too high, the film may form rapidly at the interface and become nonuniform.

Under high-concentration conditions, the amount of product increases, but because the reaction proceeds rapidly at the interface, the film tends to become thick and nonuniform.

Differences in Thread Properties With Pulling Speed

The thickness and ease of breakage of the thread change depending on the speed at which the nylon film formed at the interface is pulled upward.

If the pulling speed is too fast, the film is pulled away before a new film can form at the interface, making the thread thinner and easier to break.

Example Evaluation of Film Thickness and Mechanical Properties

The following is a reference example in which prepared nylon films were cut after drying and their film thickness and tensile properties were measured by a simple tensile test.

Tensile strength is determined by dividing the maximum load by the cross-sectional area.
Even if the film is thick, its strength may be low if the film is nonuniform or contains impurities.

Example Calculation of Tensile Strength

For a standard film with a thickness of 0.050 mm, width of 5.0 mm, and maximum load of 3.0 N, the cross-sectional area is calculated as follows.

Cross-sectional area = Width × Film thickness = 5.0 × 0.050 = 0.250 mm²

Tensile strength = Maximum load ÷ Cross-sectional area = 3.0 ÷ 0.250 = 12.0 N/mm² = 12.0 MPa

The tensile strength of this film is 12.0 MPa.

Changes in Film Properties With Drying Temperature

Higher drying temperatures make water and solvent easier to remove, but rapid drying may cause the film to shrink and become brittle.

Moderate drying increases strength, but excessive heating may cause yellowing and embrittlement and reduce the mechanical properties.

Effect of Disturbance of the Reaction Interface

In interfacial polymerization, it is important to bring the aqueous and organic layers into contact gently.
If the interface is disturbed, a uniform film becomes difficult to form.

Disturbing the interface may increase the reaction area, but it also makes it more difficult to obtain a uniform film or thread and makes recovery and washing more difficult.

Example Confirmation of Product Formation by IR Spectrum

An IR spectrum may be measured to confirm that the obtained product is a polyamide.

Confirmation of an amide I absorption near 1640 cm⁻¹ and an amide II absorption near 1540 cm⁻¹ supports formation of a polyamide structure.

Example of How to Write the Results

When the aqueous layer and organic layer were gently brought into contact, a thin white film formed at the interface.
When this film was grasped with tweezers and pulled upward, a thread-like product was continuously obtained.
This is considered to have occurred because hexamethylenediamine and sebacoyl chloride reacted at the interface between the aqueous and organic layers to produce nylon, a polyamide.

The amount of sebacoyl chloride used in the reaction was 0.0030 mol, and it was considered to be the limiting reagent.
If the formula mass of the repeating unit of nylon 6,10 is taken as 282 g/mol, the theoretical yield is 0.846 g.
Because the mass of the dried product was 0.520 g, the yield was 0.520 ÷ 0.846 × 100 = 61.5%.

The product before drying had a mass of 0.980 g, giving an apparent yield greater than 100%.
This is considered to have been because water and organic solvent remained in the product.
As the drying time was increased, the mass decreased and became nearly constant at 0.520 g after 3 hours.
Therefore, the mass after drying has stabilized must be used when calculating the yield.

Points for Connecting the Results to the Discussion

In a discussion of nylon synthesis, it is important to explain not only that a product was formed but also the characteristics of interfacial polymerization, the limiting reagent, the yield, and the relationships among washing, drying, and film properties.

• Can the reason a film forms at the interface between the aqueous and organic layers be explained?
• Can the limiting reagent be determined from the amounts of substance of the diamine and dicarboxylic acid chloride?
• Can the yield be calculated from the theoretical yield and actual yield?
• Can it be explained that insufficient drying increases the apparent product amount?
• Can it be discussed that washing removes impurities and residual solvent and changes the mass and properties?
• Can it be explained that reactant concentration affects film thickness, continuity of the thread, and nonuniformity?
• Can the reason an excessively high pulling speed makes the thread easier to break be explained?
• Can the possibility of yellowing and embrittlement at excessively high drying temperatures be discussed?
• Can polyamide formation be confirmed from amide I and amide II absorptions in the IR spectrum?

Example Discussion

In this experiment, nylon was synthesized by interfacial polymerization.
When the aqueous and organic layers were brought into contact, a white film formed at the interface between the two layers.
This is considered to have occurred because hexamethylenediamine in the aqueous layer and sebacoyl chloride in the organic layer met at the interface and formed a polyamide through condensation polymerization.
When the formed film was pulled upward, a new interface was continuously exposed and thread-like nylon was obtained.

Comparison of the amounts of reactants used showed that hexamethylenediamine was 0.0050 mol and sebacoyl chloride was 0.0030 mol.
Therefore, sebacoyl chloride was the limiting reagent.
Using 282 g/mol as the formula mass of the repeating unit of nylon 6,10, the theoretical yield was calculated to be 0.846 g, and the yield calculated from the actual yield of 0.520 g was 61.5%.

Possible reasons why the yield did not reach 100% include failure to recover all of the film and thread that formed, loss of part of the product during washing, and incomplete reaction.
In addition, if the film formed at the interface becomes thick, diffusion of the reactants to the interface may become difficult, potentially making local polymerization more difficult to proceed.
Although interfacial polymerization proceeds rapidly, the yield can vary greatly depending on product recovery and washing operations.

Under conditions with higher reactant concentrations, the product amount increased, but the film tended to become thicker, more nonuniform, and more brittle.
At high concentrations, polymerization proceeds rapidly at the interface, so locally thick films rather than uniform thin films are considered to have formed.
On the other hand, at low concentrations, the film was thin and easily broke while being pulled out as a thread.
Therefore, to obtain a continuous thread-like product, the reactant concentration and pulling speed must be adjusted appropriately.

In the IR spectrum, amide I absorption near 1640 cm⁻¹ and amide II absorption near 1540 cm⁻¹ were observed.
These absorptions are derived from the amide bonds of polyamide and support the formation of nylon.
However, if washing is insufficient, unreacted substances and solvent may remain and affect the yield and film properties.
Therefore, when evaluating the product, not only the yield but also the appearance, drying state, washing state, and IR spectrum must be examined comprehensively.

Summary

In nylon synthesis by interfacial polymerization, a polyamide film is formed at the interface between the aqueous and organic layers.
The product yield is calculated using the theoretical yield determined from the limiting reagent and the actual yield after drying.

This reference example addressed theoretical yield, yield, drying time, washing conditions, reactant concentration, pulling speed, film thickness, tensile strength, and confirmation of product formation by IR.
In a report, it is useful to discuss the mechanism of interfacial polymerization, yield calculations, product properties, and differences caused by operating conditions in relation to one another.

What Is Interfacial Polymerization?

Interfacial polymerization is a method in which a polymerization reaction is carried out at the interface between two liquid phases that do not readily mix with one another.
In nylon synthesis, a diamine may be dissolved in one phase and a dicarboxylic acid chloride or similar compound in the other phase, and the reaction is allowed to occur at the interface where the two phases come into contact.
The reaction proceeds mainly near the interface, and a polymer film forms at the interface.

When the nylon film formed at the interface is removed, the monomers again come into contact at the new interface and further polymerization proceeds.
Therefore, by continuously pulling the film upward, thread-like nylon may be continuously removed.

Discussion of Amide-Bond Formation

Nylon is a polymer containing amide bonds in its main chain.
When the amino groups of a diamine react with carboxylic acid derivatives such as dicarboxylic acid chlorides, amide bonds are formed.
Repeated occurrence of this reaction at the functional groups on both ends forms long polyamide chains.

In a discussion of nylon synthesis, rather than simply writing that “a polymer was formed,” it is useful to explain that a polyamide was obtained as a result of amide-bond formation.
If an IR spectrum or similar measurement was performed, absorption derived from the amide bonds can provide evidence for the structure.

Why a Film Forms

A film forms during nylon synthesis because the polymer is produced at the interface between the two liquid phases.
The produced nylon is often poorly soluble in the reaction solutions and therefore appears near the interface as a solid or gel-like film.
This film is an important observation indicating that the reaction is localized at the interface.

The thickness and uniformity of the film are affected by monomer concentration, reaction rate, stability of the interface, and mixing state of the solutions.
If the interface is disturbed excessively, small aggregates or nonuniform products rather than a uniform film may form.

Why the Product Can Be Pulled Out as a Thread

When the nylon film formed at the interface is grasped and pulled upward, it may be removed as a thread-like product.
This occurs because the polymer film formed at the interface is continuously connected and further polymerization proceeds at the newly formed interface as the film is pulled upward.

Whether the thread can be continuously pulled out is affected by the strength of the film, formation rate, pulling speed, and stability of the interface.
If the pulling speed is too high, the film breaks before it can form sufficiently and the thread becomes easier to break.
Conversely, if the pulling speed is too slow, the product may accumulate thickly at the interface and become nonuniform.

How to Determine Yield

In nylon synthesis, the yield may be determined from the mass of the dried product.
Yield indicates how much product was actually recovered compared with the theoretically obtainable mass of nylon.
The smaller amount of substance among the monomers used in the reaction may determine the theoretical product amount.

Yield (%) = Mass of nylon actually obtained ÷ Theoretical product amount × 100

However, if solvent, water, unreacted monomers, salts, or similar substances remain in the product, the apparent mass becomes larger.
Therefore, when discussing yield, the drying state and adequacy of washing must also be considered.

Causes of Low Yield

Causes of low yield in nylon synthesis include insufficient reaction progress, low monomer concentration, disturbance of the interface that prevents efficient recovery of the product, loss of product during washing or transfer, and loss of some product before drying.
In interfacial polymerization, because the reaction proceeds at the interface, the condition of the interface greatly affects the product amount.

In addition, if dicarboxylic acid chlorides or similar compounds react with water and undergo hydrolysis, the amount available for polymerization with the diamine decreases.
In this case, the amount of desired nylon produced may decrease.

Discussion When the Yield Is Too High

If the yield is excessively higher than the theoretical value, the product may not have been completely dried.
Nylon may retain water or solvent, and insufficient drying causes the measured mass to be larger than the actual polymer mass.
Unreacted monomers, salts, solvents, and impurities remaining in the product may also increase the apparent yield.

Therefore, a high yield does not necessarily indicate a good result.
If washing and drying are insufficient, the product may have a large mass but low purity.

Discussion of Film Properties

The properties of a nylon film are affected by molecular weight, film thickness, uniformity, crystallinity, drying state, residual solvent, and other factors.
If the film is strong and can be continuously pulled out, polymer chains of a certain length are considered to have formed and gathered into a coherent film.
On the other hand, if the film is brittle, breaks immediately, or crumbles, possible causes include low molecular weight, an excessively thin film, disturbance of the interface, or a nonuniform product.

The condition of the film is affected not only by the reaction conditions but also by the way it is pulled, washed, and dried.
If it is pulled too strongly, the film becomes easier to break, and excessive drying may make it feel hard and brittle.

Discussion When the Thread Breaks Easily

If the nylon thread breaks easily, possible causes include low molecular weight of the formed polymer, a thin film, an unstable interface, an excessively high pulling speed, and residual impurities or unreacted substances in the product.
If the polymer chains are sufficiently long and entangled with one another, the thread becomes relatively resistant to breakage.

Conversely, low-molecular-weight polymers and nonuniform films readily break when force is applied.
The ease with which the thread breaks provides a clue for considering the molecular weight of the product and the uniformity of film formation.

Causes of a Nonuniform Film

Causes of a nonuniform film include disturbance of the interface, excessive mixing of the solutions, local differences in monomer concentration, excessively rapid reaction, and inconsistent pulling operation.
In interfacial polymerization, because the reaction proceeds at the boundary between liquid phases, the stability of the interface is important.

If the interface is disturbed, the reaction region may spread or the product may become finely dispersed, making it difficult to form a uniform film.
As a result, variations occur in film thickness and strength.

Effect of Monomer Concentration

Monomer concentration affects the reaction rate, film thickness, amount of product, and molecular weight.
If the concentration is low, the amount of monomer that comes into contact at the interface decreases, and the amount of product may become smaller.
The film may also become thin and the thread easier to break.

On the other hand, if the concentration is too high, the reaction may proceed rapidly, making the film thick and nonuniform or producing lump-like products.
It is important to form a uniform film under appropriate concentration conditions.

Effect of Monomer Ratio

In condensation polymers such as nylon, the ratio of reacting functional groups is important.
If the amount ratio of the diamine and dicarboxylic acid derivative deviates greatly, one type of functional group becomes deficient and chain growth becomes more likely to stop.
As a result, high-molecular-weight nylon may become difficult to obtain.

To obtain a high-molecular-weight product, the reacting functional groups must be present in an appropriate ratio.
Deviations in the monomer ratio may affect not only the yield but also film strength and ease of thread breakage.

Effect of Hydrolysis

Highly reactive monomers such as dicarboxylic acid chlorides may react with water and undergo hydrolysis.
If hydrolysis occurs, the amount of acid chloride available for polymerization with the diamine decreases, potentially lowering both the amount and molecular weight of the nylon produced.

Because the aqueous layer is involved in interfacial polymerization, hydrolysis of reactive monomers is an important point for discussion.
If the reaction is delayed or the interface is disturbed, hydrolysis may proceed instead of the desired amide-bond formation.

Purpose of Washing and Discussion

Nylon after synthesis may contain unreacted monomers, acids, salts, solvents, and other substances.
Washing is performed to remove these impurities and bring the product closer to a pure state.
If washing is insufficient, the mass of the product may be overestimated and the film properties may also be affected.

On the other hand, if the film or thread breaks during washing or small pieces of product are washed away, the yield decreases.
Washing is an operation that increases purity but may also cause product loss.

Purpose of Drying and Discussion

Drying is performed to remove water and solvent contained in the product.
If the nylon is not sufficiently dried, the measured mass includes water and solvent and the yield is overestimated.
Residual water or solvent may also affect the softness, stickiness, and strength of the film.

If drying is insufficient, errors occur not only in the yield but also in evaluation of the film properties and physical properties.
Comparing the mass before and after drying makes it easier to judge whether drying is sufficient.

Discussion of Product Color and Appearance

Products obtained in nylon synthesis may be observed as white or translucent films or threads.
If the product is colored, unreacted substances, impurities, solvents, decomposition products, or similar components may remain.
Transparency and the degree of cloudiness are also affected by film thickness, crystallinity, drying state, and surface roughness.

Appearance is qualitative information but provides clues for judging the condition of the product.
In a report, specifically recording color, shape, film uniformity, thread strength, and similar observations makes discussion easier.

When Confirming the Product by IR Spectrum

IR spectroscopy may be used to confirm the structure of nylon.
Because nylon contains amide bonds, observation of absorption derived from amide bonds provides evidence of polyamide formation.
In addition, the progress of the reaction can be discussed by examining whether functional groups derived from the monomers have decreased.

However, molecular weight and film strength cannot be determined from the IR spectrum alone.
IR is useful for structural confirmation, but physical properties and molecular weight must be discussed in combination with other measurement results.

Discussion When the Amount of Product Is Small

If the amount of product is small, possible causes include low monomer concentration, short reaction time, small interfacial contact area, hydrolysis of a reactive monomer, or incomplete product recovery.
In interfacial polymerization, because the reaction proceeds at the interface, insufficient supply of monomers to the interface results in a smaller product amount.

If the film cannot be pulled up successfully and some of the product remains in the solution, the amount recovered also decreases.
When the amount of product is small, not only the amount of reaction but also the recovery operation should be discussed.

Discussion When the Product Forms Lumps

Nylon may form lumps instead of a clean film or thread.
This is considered to occur when the interface is greatly disturbed and the reaction proceeds locally or nonuniformly.
If the solutions are mixed too strongly, the two phases become finely dispersed and reactions occur simultaneously at many small interfaces, making granular or lump-like products more likely to form instead of a film.

Lump-like products tend to be washed and dried nonuniformly and may introduce errors into yield and physical-property evaluation.
In interfacial polymerization, it is important to maintain the interface during the reaction.

Relationship Between Molecular Weight and Film Strength

The strength of nylon films and threads is affected by molecular weight and entanglement of the polymer chains.
The higher the molecular weight, the longer the polymer chains become, and chain entanglement and intermolecular interactions tend to become stronger, so the strength of the film or thread may increase.
Conversely, if the molecular weight is low, the film may become brittle and easier to break.

However, film strength is not determined by molecular weight alone.
Film thickness, uniformity, drying state, crystallinity, and orientation in the pulling direction also have an effect.

Discussion of Nylon Properties

Nylon is a polyamide and has intermolecular interactions associated with amide bonds.
Because amide bonds are involved in hydrogen bonding, nylon may exhibit relatively strong mechanical properties.
In addition, regular arrangement of the molecular chains produces crystallinity, which affects strength, melting point, and solubility.

The nylon obtained in an experiment is not necessarily as high in quality as commercially available nylon fibers.
Because molecular weight, orientation, crystallinity, purification state, and drying state differ, differences in strength and appearance occur.
In student experiments, it is useful to distinguish between successful synthesis and the physical properties of the material.

When the Result Can Be Considered Good

A good result in nylon synthesis is one in which a clear film forms at the interface, can be continuously pulled out as a thread, and a certain amount of product is obtained after washing and drying.
In addition, if the product is not excessively sticky and maintains a film-like or thread-like form to some extent, polymer formation can be considered to have proceeded.

If absorption derived from amide bonds is confirmed by IR or a similar method, structural evidence is also obtained.
However, it is important to make an overall judgment based not only on the yield and appearance but also on washing, drying, and recovery operations.

Example Discussion When the Experiment Did Not Go Well

If nylon synthesis does not go well, causes can be considered from results such as failure to form a film, inability to pull out a thread, a small amount of product, immediate film breakage, formation of lumps, low yield, or excessively high yield.
Organizing the factors separately into reaction conditions, interface condition, monomer ratio, hydrolysis, recovery, washing, and drying makes the discussion easier.

How to Write Points for Improvement

In a discussion of nylon synthesis, including not only sources of error but also points for improvement makes the report easier to organize.
Improvements can be organized by considering maintenance of the interface, monomer concentration and ratio, pulling operation, washing, and drying separately.

Improvements to Reaction Operation

• Bring the two liquid phases into contact gently
• Avoid disturbing the interface excessively
• Prepare monomer concentrations accurately
• Use an appropriate ratio of diamine to dicarboxylic acid derivative
• Suppress hydrolysis of reactive monomers as much as possible

Improvements to Film and Thread Recovery

• Pull the film upward slowly at a constant speed
• Avoid pulling too strongly
• Do not leave product adhered to equipment
• Recover finely broken product as much as possible
• Take care to prevent the product from being washed away during washing

Improvements to Washing and Drying

• Wash away unreacted monomers and by-products sufficiently
• Be careful not to lose product through excessive washing
• Keep the drying conditions constant
• Check the change in mass before and after drying
• Avoid overestimating the yield because of insufficient drying

Difference Between a Superficial Discussion and a Good Discussion

In a discussion of nylon synthesis, simply writing that “a film formed,” “a thread formed,” or “the yield was low” results in a superficial discussion.
Relating interfacial polymerization, amide bonds, monomer concentration, disturbance of the interface, film properties, and the effects of washing and drying produces a more persuasive discussion.

Examples of Expressions That Can Be Used in Reports

The following expressions can be used when writing the results and discussion of a nylon synthesis experiment.
Adjust the necessary parts according to your own experimental results.

• In interfacial polymerization, monomers react at the interface between two liquid phases that do not readily mix.
• The reaction between the diamine and dicarboxylic acid derivative is considered to have produced a polyamide containing amide bonds.
• The formation of a film-like product at the interface indicates that nylon was formed at the interface.
• When the film was pulled upward, a new interface appeared and polymerization is considered to have proceeded continuously.
• Possible reasons the thread broke easily include insufficient molecular weight, nonuniformity of the film, and the effect of pulling speed.
• Possible causes of the low yield include insufficient reaction progress, loss of product during recovery, and hydrolysis.
• If the yield was excessively high, the mass may have been overestimated because of insufficient drying or residual unreacted substances.
• Washing is important for removing unreacted monomers and by-products.
• Insufficient drying affects both yield and evaluation of the physical properties of the film.
• The strength of nylon is affected by molecular weight, entanglement of molecular chains, and film uniformity.

Points to Check When Discussing Nylon Synthesis

Checking the following points before writing the report makes the discussion easier to write.

• Is the mechanism of interfacial polymerization explained?
• Is amide-bond formation explained?
• Is the reason the film formed described?
• Is the reason the product could be pulled out as a thread described?
• Is the method for calculating yield shown?
• Are causes of low yield considered separately in terms of reaction and recovery?
• Is overestimation of yield caused by insufficient drying considered?
• Are film strength and ease of breakage related to molecular weight and film uniformity?
• Is the effect of disturbance of the interface discussed?
• Are the effects of washing and drying operations described?
• Are the effects of monomer concentration and ratio considered?
• Do the points for improvement correspond to the sources of error?

Summary

In a nylon synthesis experiment, a polyamide containing amide bonds is synthesized through the reaction of a diamine and a dicarboxylic acid derivative or similar compounds.
In interfacial polymerization, the reaction proceeds at the interface between two solutions that do not readily mix, forming a film-like nylon product.
When this film is pulled upward, the reaction continues at the newly exposed interface, and the product may be removed as a thread.

Causes of low yield include insufficient reaction progress, deviation in monomer ratio, hydrolysis of the acid chloride, loss of product during recovery, and loss during washing.
On the other hand, if the yield is excessively high, the mass may have been overestimated because of insufficient drying or residual unreacted monomers, solvent, or by-products.

In a report, rather than simply writing that “a nylon thread was formed,” discuss the principle of interfacial polymerization, amide-bond formation, film formation, yield, properties of the film and thread, washing, drying, and disturbance of the interface in relation to one another.
In nylon synthesis, not only the amount of product but also film uniformity and ease of thread breakage are important points for discussion.