A new type of polypeptide(poly(-benzyl-L-glutamate)(PBLG))modified hydroxyapatite(HA)/poly(L-lactide)(PLLA)nanocomposites(PBLG-g-HA/PLLA)were prepared by the solvent-mixing method,and their mechanical and thermal properties were investigated.The tensile test showed that the mechanical properties of PBLG-g-HA/PLLA nanocomposites were better than that of PLLA,even a 0.3 wt%content of PBLG-g-HA in the nanocomposites could make the tensile strength 12%higher than that of the neat PLLA sample,and the tensile modulus was about 17%higher than that of the PLLA sample.The thermal gravimetric analysis(TGA)showed that the PBLG-g-HA/PLLA composites have better thermal stability than the PLLA sample.The differential scanning calorimetry(DSC)was used to characterize the effect of PBLG-g-HA on the crystallization of PLLA.The isothermal crystallization behavior showed that the half crystallization time(t1/2)of PBLG-g-HA/PLLA was much shorter than that of the PLLA sample.When the PBLG-g-HA content was 10%,t1/2 was only 18.7 min,while t1/2 of the PLLA sample was 61.4 min.The results showed that the PBLG-g-HA worked as a nucleating agent and enhanced the crystallization speed of PLLA.
Intelligent polymers or stimuli-responsive polymers may exhibit distinct transitions in physical-chemical properties, including conformation, polarity, phase structure and chemical composition in response to changes in environmental stimuli. Due to their unique 'intelligent' characteristics, stimuli-sensitive polymers have found a wide variety of applications in biomedical and nanotechnological fields. This review focuses on the recent developments in biomedical application of intelligent polymer systems, such as intelligent hydrogel systems, intelligent drug delivery systems and intelligent molecular recognition systems. Also, the possible future directions for the application of these intelligent polymer systems in the biomedical field are presented.
