Influence of plasticizer on soft polymer gelation

Area of Science:

• Polymer Science
• Biomaterials Engineering
• Dental Materials Science

Background:

• Soft polymer gels are crucial as short-term denture-lining materials in prosthodontics.
• Understanding the relationship between plasticizer composition and gel properties is essential for optimizing performance.

Purpose of the Study:

• To investigate how variations in plasticizer liquid composition affect the gel strength and gelation time of soft polymer systems.
• To determine the influence of specific plasticizers and ethyl alcohol on the physical properties of denture lining materials.

Main Methods:

• Poly(ethylmethacrylate) co-polymers were formulated with varying combinations of ethyl alcohol and ester plasticizers (dibutyl phthalate, butylphthalyl butylglycolate, benzyl salicylate).
• Gelation rate and time were measured using a reciprocating rheometer.
• Gel strength was assessed via seven-day puncture strength tests.

Main Results:

• Increased ethyl alcohol content led to a rapid increase in gelation rate and shorter gelation times.
• Lower-molecular-weight esters resulted in significantly shorter gelation times.
• Higher-molecular-weight esters produced stronger gels, with a linear relationship observed between log gelation times and puncture strength.
• The polymer-to-plasticizer ratio significantly influenced both puncture strength and gelation time.
• Ethyl alcohol's polar bonding strongly affected gel formation rate and strength, more so than the ester plasticizers' cohesive energy parameter.

Conclusions:

• Controlled adjustments to plasticizer composition, particularly ethyl alcohol content and ester molecular weight, can effectively modify the plasticity and gel strength of soft polymer dental materials.
• These findings enable the tailoring of denture lining materials to meet diverse clinical prosthodontic requirements.