What is the Chemical Formula of Polycaprolactone?
Polycaprolactone is an organic high molecular polymer with the chemical formula (C6H10O2)n. It has the property of being well soluble in aromatic compounds, ketones and polar solvents. It is made of ring-opening polymerization of ε-caprolactone using a metal organic compound (such as tetraphenyltin) as a catalyst and dihydroxy or trihydroxy as an initiator. It is polymeric polyester.
What are the Physical and Chemical Properties of Polycaprolactone?
Polycaprolactone appears as a white solid powder, which is non-toxic, insoluble in water, and easily soluble in a variety of polar organic solvents. Polycaprolactone has good shape memory temperature control properties and the physical properties of a nylon-like plastic, softening to a putty-like consistency at just 60°C, which can be achieved easily by simply immersing it in hot water.
The specific heat and conductivity of polycaprolactone are very low, and it is not difficult to operate by hand at this temperature. This makes it ideal for small-scale modeling, part manufacturing, repair of plastic objects, and rapid prototyping where heat resistance is not required. Although softened polycaprolactone adheres readily to many other plastics at higher temperatures, if the surface is cooled, the stickiness can be minimized while still maintaining a flexible quality.
What are the Characteristics of Polycaprolactone?
- Biocompatibility
It has good compatibility with biological cells in the body. Cells can grow normally on its scaffold and can be degraded into CO2 and H2O.
- Biodegradability
In soil and water environments, it can be completely decomposed into CO2 and H2O.
- Good compatibility
It can be well compatible with PE, PP, ABS, AS, PC, PVAC, PVB, PVE, PA, natural rubber, etc.
- Good solvent solubility
It is soluble well in aromatic compounds, ketones and polar solvents.
What is the Degradation Process of Polycaprolactone?
Polycaprolactone is a chemically synthesized biodegradable polymer material. Its molecular structure contains an ester group structure -COO. In nature, the ester group structure is easily decomposed by microorganisms or enzymes, and the final products are CO2 and H2O: The specific process is as follows
Stage 1: The material absorbs moisture from its surrounding environment, a process that takes days or months, depending on the material's properties and surface area.
Stage 2: the polymer backbone breaks the chemical chain due to hydrolysis or enzymatic hydrolysis, resulting in a decrease in molecular weight and mechanical properties.
Stage 3: After the loss of strength, the polymer turns into oligomer fragments and the overall mass begins to decrease.
Stage 4: The oligomers are further hydrolyzed into smaller fragments, which are absorbed by phagocytes, or further hydrolyzed to generate CO2 and H2O.
What is the Shape Memory Function of Polycaprolactone?
The shape memory function of polycaprolactone materials mainly comes from the existence of two incompletely compatible phases within the material: a stationary phase that maintains the shape of the molded product and a reversible phase that undergoes a reversible change from softening to hardening as the temperature changes. The reversible phase includes a crystalline state with a lower melting point (Tm) or a glassy state with a lower glass transition temperature (Tg), and has a physical cross-linked structure. The stationary phase can have a physical cross-linked structure (such as molecular entanglement formed by a phase with a higher Tm or Tg at a lower temperature) or a chemical cross-linked structure. The stationary phase and the reversible phase have different softening temperatures (labeled Ta and Tb respectively). During the primary molding process, the material is heated above Ta. At this time, the stationary phase and the reversible phase are both in a softened state. After shaping, it is cooled to below Tb, the stationary phase and the reversible phase harden successively, and the material is shaped. Secondary molding is to heat the molding material to the softening temperature of the reversible phase (Tb < T < Ta). The reversible phase softens and can be made into any second shape. The new shape is obtained by maintaining the stress and cooling and fixing. If the reversible phase is softened by heating again to a suitable temperature, the stationary phase will return the product to its original shape under the action of recovery stress.
