Polycaprolactone mechanism

P. Jarrett, Ph.D. Dissertation in Polymer Science(l983) The Morphology and Mechanism of the Biodegradation of Polycaprolactone, Institute of Materials Science, University of Connecticut, Storrs, CT. 

PLC Polycaprolactone Polyester polyol Programmable logic controller A polymer made by ring opening caprolactam. A chemical building block. The polyester provides good solvent resistance and good mechanical properties in the final polyurethane. 

As pointed out by Heller (2), polymer erosion can be controlled by the following three types of mechanisms (1) water-soluble polymers insolubilized by hydrolytically unstable cross-links (2) water-insoluble polymers solubilized by hydrolysis, ionization, or protonation of pendant groups (3) hydrophobic polymers solubilized by backbone cleavage to small water soluble molecules. These mechanisms represent extreme cases the actual erosion may occur by a combination of mechanisms. In addition to poly (lactic acid), poly (glycolic acid), and lactic/glycolic acid copolymers, other commonly used bioerodible/biodegradable polymers include polyorthoesters, polycaprolactone, polyaminoacids, polyanhydrides, and half esters of methyl vinyl ether-maleic anhydride copolymers (3). 

The IPNs prepared were composed of a rubbery polyurethane and a glassy epoxy component. For the polyurethane portion, a carbodiimide-modified diphenyl-methane diisocyanate (Isonate 143L) was used with a polycaprolactone glycol (TONE polyol 0230) and a dibutyltin dilaurate catalyst (T-12). For the epoxy, a bisphenol-A epichlorohydrin (DER 330) was used with a Lewis acid catalyst system (BF -etherate). The catalysts crosslink via a ring-opening mechanism and were intentionally selected to provide minimum grafting with any of the polyurethane components. The urethane/epoxy ratio was maintained constant at 50/50. A number of fillers were included in the IPN formulations. The materials used are shown in Table I. 

Low profile plastics are added to reduce shrinkage during cure. They are normally thermoplastics that include polyvinyl acetates, polymethyl methacrylate, and copolymers with other acrylate, vinyl chloride-vinyl acetate copolymers, polyurethane, polystyrene, polycaprolactone, cellulose acetate butyrate, saturated polyester, and styrene butadiene copolymers. More details about the low profile additive (LPA) mechanism are published in the literature. ... 

Huang ZM, Zhang YZ (2005) Micro-structures and mechanical performance of co-axial nanofibers with drug and protein cores and polycaprolactone shells. Chem J Chin Univ Chin 26(5) 968-972... 

Wise SG et al (2011) A multilayered synthetic human elastin/polycaprolactone hybrid vascular graft with tailored mechanical properties. Acta Biomater 7(1 ) 295—303... 

Polycaprolactone synthesis was performed in two scales preparative, and screening scale. In preparative scale, synthesis was performed in a three-neck flask with an overhead mechanical stirrer and a temperature controller in presence of an anhydrous solvent. Toluene was selected as the best solvent for PCL synthesis [24], In screening scale, synthesis was performed in smaller scale inside glass vials in a J-Kem parallel synthesizer with either 6-vial or 12-vial reactor. 

S. Sant, D. Iyer, A.K. Gaharwar, A. Patel, A. Khademhosseini, Effect of biodegradation and de novo matrix synthesis on the mechanical properties of valvular interstitial cell-seeded polyglycerol sebacate— polycaprolactone scaffolds. Acta Biomater. 9 (2013) 5963—5973, doi 10.1016/j.actbio.2012.11.014. 

Semba, T., Kitagawa, K., Ishiaku, U.S., Hamada, H. The Effect of crosslinking on the mechanical properties of polylactic acid/polycaprolactone blends. J. Appl. Polym. Sci. 101(3), 1816-1825 (2006)... 

Chemical functionalization of CNT surfaces could improve their dispersion in the polymer matrix and enhance the nanotube-polymer interfacial interaction and the mechanical load transfer. The effects of nanotube functionalization on the properties of CNT-TPU composites have been investigated in details. Xia and Song have synthesized polycaprolactone polyurethane (PU)-grafted SWNTs (PU-g-SWNTs) and corresponding PU-g-SWNT-PU composites by in-situ polymerization. The results show that PU-g-SWNTs improve the dispersion of SWNTs in the PU matrix and strengthen the interfacial interaction between the PU and SWNTs. Compared with neat PU and pristine SWNT PU composites, PU-g-SWNT-PU composites demonstrate remarkable enhancement on Young s modulus. The Young s modulus of a 0.7 wt /o PU-g-SWNT-PU composite increases by 178% over the blank PU and 88% over the 0.7 wt% pristine SWNT-PU composite, respectively. 

---