A biodegradable poly(L-lactic acid) (PLLA) macroporous scaffold with a regular and highly interconnected structure in the size range from 50 to 150 mu m was fabricated from a PLLA--dioxane--water ternary system with the use of the thermally induced phase separation (TIPS) process. The phase diagram of PLLA with molecular weight above 200,000 was measured. It was found that a small change in the water content in the solvent caused a large shift in the cloud-point temperature. The porous morphology of the scaffold was closely related to the quenching route and formulation parameters, including polymer concentration, quenching temperature, aging time, and solvent composition of the ternary system. The porous morphology development in the scaffold was recorded as a function of aging time by scanning electronic microscopy (SEM). For systems with lower polymer concentrations (<4.5 wt%), polymer sedimentation occurred in the later stages of phase separation. A slight increase in the water content of the solvent mixture caused the sedimentation boundary to expand to higher polymer concentration. For systems with higher polymer concentrations (> or = 4.5 wt%), the development of phase separation was restricted by gelation that resulted from the crystallization of the PLLA chains. This gelation effect was greater at high polymer concentrations and low quenching temperatures. The macroporous expected scaffold could be optimized from the slow development of phase separation during the long coarsening process.

A biodegradable poly(L-lactic acid) (PLLA) macroporous scaffold with a regular and highly interconnected structure in the size range from 50 to 150 m was fabricated from a PLLA-dioxane-water ternary system with the use of the thermally induced phase separation (TIPS) process. The phase diagram of PLLA with molecular weight above 200,000 was measured. It was found that a small change in the water content in the solvent caused a large shift in the cloud-point temperature. The porous morphology of the scaffold was closely related to the quenching route and formulation parameters, including polymer concentration, quenching temperature, aging time, and solvent composition of the ternary system. The porous morphology development in the scaffold was recorded as a function of aging time by scanning electronic microscopy (SEM). For systems with lower polymer concentrations (<4.5 wt%), polymer sedimentation occurred in the later stages of phase separation. A slight increase in the water content of the solvent mixture caused the sedimentation boundary to expand to higher polymer concentration. For systems with higher polymer concentrations (>4.5 wt%), the development of phase separation was restricted by gelation that resulted from the crystallization of the PLLA chains. This gelation effect was greater at high polymer concentrations and low quenching temperatures. The macroporous expected scaffold could be optimized from the slow development of phase separation during the long coarsening process.

Zinc-glutarate (ZnGA) is a promising catalyst that can form polymers from CO2 and epoxides, thereby contributing to the development of CO2 utilization technologies and future sustainability. One of the obstacles...

This work suggests an in situ synthetic approach for nanoplatforms based on microporous organic polymer (MOP) chemistry. Anchoring groups for catalytic species could be simultaneously introduced to nanoplatforms in the synthesis of MOPs. Poly­(acrylic acid) (PAA) served not only as a surfactant for the controlled synthesis of nanoscaled MOPs but also as an anchoring group for the introduction of catalytic species. Zinc ions could be coordinated to MOP nanoparticles bearing PAA (MOPN-PAAs) to form MOPN bearing ZnPAA (MOPN-ZnPAA). The MOPN-ZnPAA was well dispersed in neat ε-caprolactone (ε-CL) and showed excellent catalytic activities in the ring-opening polymerization of ε-CL to polycaprolactone (PCL). In addition, the MOPN-ZnPAA could be recycled, maintaining catalytic performance in five successive reactions.