José E. Báez

A Comparison of Three Different Biodegradable Aliphatic Oligoesters (PGA, PLLA, and PCL) with Similar Linear Alkyl End Groups by DSC and SAXS

The biodegradable aliphatic oligoesters polyglycolide (PGA), poly(L-lactide) (PLLA), and poly(ϵ-caprolactone) (PCL) with similar number-average molecular weight Mn values but different linear alkyl end groups [CH3−[CH2−CH2]m−CH2−] were compared in terms of their physical properties, parameters such as melting temperature (Tm), crystallinity (xi), long period (L), and lamella thickness (D). They were analyzed by DSC and SAXS. The effect of a longer and nonpolar alkyl end group such as docosyl [CH3−[CH2−CH2]10−CH2−] on the long period (L) was more evident for PCL because it was the most nonpolar species in the family of oligoesters analyzed.

Poly(ε-caprolactone) Diols (HOPCLOH) and Their Poly(ester-urethanes) (PEUs): The Effect of Linear Aliphatic Diols [HO–(CH2)m–OH] as Initiators

ABSTRACT α,ω-Hydroxy telechelic poly(ε-caprolactones) were prepared by ring-opening polymerization of the ε-caprolactone catalyzed by ammonium decamolybdate in the presence of different aliphatic diols [HO–(CH2)m–OH, where m = 2, 4, 6, 8, 10, 12, 14, and 16] as initiators to obtain a family of α,ω-hydroxy telechelic poly(ε-caprolactone) [HO–PCL–O–(CH2)m–O–PCL–OH, m = 2, 4, 6, 8, 10, 12, 14, and 16]. The content of the alkyl group (AG) (–(CH2)m–) had an important effect on the crystallinity (xi) of α,ω-hydroxy telechelic poly(ε-caprolactone), showing a proportional relationship. In poly(ester-urethanes) derived from α,ω-hydroxy telechelic poly(ε-caprolactones) and 1,6-hexamethylene diisocyanate, the AG also showed a similar effect on the xi and eventually on the mechanical properties, increasing the values of the modulus. Therefore, AG content was a factor to induce a plastic behavior in poly(ester-urethanes). The effect of AG on the water uptake of poly(ester-urethanes) after 1 week was negligible. GRAPHICAL ABSTRACT

Poly(L-lactide) macrodiols (HOPLLAOH): Influence of linear alkyl diols as initiators: Synthesis and characterization

ABSTRACT A series of α,ω-hydroxy telechelic poly(L-lactide)s (HOPLLAOHs) were synthesized by ring-opening polymerization (ROP) of L-lactide (L-LA) using tin octoate [Sn(Oct)2] as catalyst and a family of linear alkyl diols as initiators [HO–[CH2]m–OH, where m = 2, 4, 6, 8, 10, and 12]. A systematic analysis of these HOPLLAOHs species in terms of their thermal properties was realized by DSC. In this sense, the linear alkyl group had an important influence on the glass transition temperature (Tg); a relatively high content of alkyl group on the HOPLLAOH increased the flexibility of the polyester, evidenced by a value of Tg inversely proportional to the weight percent of the alkyl group. Besides, the alkyl groups had an effect on the crystallization temperature (Tc), melting temperature (Tm), and crystallinity (xi). Additionally, HOPLLAOHs were characterized by 1H and 13C NMR, FT-IR, MALDI-TOF, and GPC.