The overall goal of this study was to synthesize semicrystalline poly(ε-caprolactone) (PCL) copolymer networks with stimuli-responsive shape memory behavior. Herein, we investigate the influence of a cinnamoyl moiety to design shape memory polymer networks with tunable transition temperatures. The effect of various copolymer architectures (random or ABA triblock), the molecular weight of the crystalline domains, PCL diol, (M(w) 1250 or 2000 g mol(-1)) and its composition in the triblock (50 or 80 mol %) were also investigated. The polymer microstructures were confirmed by NMR, DSC, WAXS and UV-vis spectroscopic techniques. The thermal and mechanical properties and the cross-linking density of the networks were characterized by DSC, tensile testing and solvent swelling, respectively. Detailed thermomechanical investigations conducted using DMA showed that shape memory behavior was obtained only in the ABA triblock copolymers. The best shape memory fixity, R(f) of ~99% and shape recovery, R(r) of ~99% was obtained when PCL diol with M(w) 2000 g mol(-1) was incorporated in the triblock copolymer at a concentration of 50 mol %. The series of triblock copolymers with PCL at 50 mol % also showed mechanical properties with tunable shape memory transition temperatures, ranging from 54 °C to close to body temperature. Our work establishes a general design concept for inducing a shape memory effect into any semicrystalline polyester network. More specifically, it can be applied to systems which have the highest transition temperature closest to the application temperature. An advantage of our novel copolymers is their ability to be cross-linked with UV radiation without any initiator or chemical cross-linker. Possible applications are envisioned in the area of endovascular treatment of ischemic stroke and cerebrovascular aneurysms, and for femoral stents.

Novel polymers containing quaternary functional groups, with and without (control copolymer) PEG side chains, were synthesized and characterized for their ability to lyse the phospholipid membranes of liposome vesicles. Calcein loaded unilamellar vesicles composed of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) were used to mimic red-blood cell membranes, and a 80:20 (mol/mol) mixture of 1,2-dioleoyl-sn-glycero-3-phosphatidyl ethanolamine (DOPE) and 1,2-dioleoyl-sn- glycero-3-[phospho-rac-(1-glycerol)] (DOPG) was used to mimic the outer cell-membrane of the gram-negative bacteria, E. coli. For DOPE/DOPG = 80:20 (mol/mol) liposome vesicles, the PEG bottle brush copolymer caused leakage of the encapsulated Calcein dye, whereas the control copolymer did not cause any leakage. Both the bottle brush copolymer and the copolymer without PEG side chains had no effect on the zwitterionic DOPC liposome vesicles indicating that the RBC membrane composition is not disrupted by either copolymer architecture. The PEG bottle brush copolymer did not affect the colloidal size of the DOPE/DOPG = 80:20 (mol/mol) liposome vesicles, but on the addition of Triton-X 100, the vesicles disappeared. This provided evidence that the dye leakage was caused by compromising the integrity of the vesicle membrane by the bottle brush polymer architecture. Such partial disruption was preceded by the entropic templating of lipid membranes by the PEG side chains of the bottle brush copolymer. By careful comparison with non-PEGylated cationic polymers, Quart, the importance of PEG side chains in the membrane disrupting activity of the PEGylated cationic polymer, QPEG, was demonstrated. This finding itself is interesting and can contribute to the expansion of the design of membrane disrupting materials.

Protein-resistant polyethylene-block-poly(ethylene glycol) (PE-b-PEG) copolymers of different molecular weights at various concentrations were compounded by melt blending with polypropylene (PP) polymers in order to enhance their antifouling properties. Phase separation of the PE-b-PEG copolymer and its migration to the surface of the PP blend, was confirmed by attenuated total reflectance-Fourier transform infrared, X-ray photoelectron spectroscopy, and static water contact angle measurements. Enrichment of PEG chains at the surface of the blends increased with increasing PE-b-PEG copolymer concentration and molecular weight. The PP blends compounded with PE-b-PEG copolymer having the lowest molecular weight (875 g mol 21 ), at the lowest concentration (1 wt %), gave the lowest bovine serum protein adsorption (30% less) compared to that of neat PP. At higher concentrations (5 and 10 wt %), and higher molecular weights (920, 1400, and 2250 g mol 21 ), the PE-b-PEG copolymers leached-out resulting in protein adsorption comparable to that of neat PP.Polypropylene (PP) is a widely used material for biomedical applications due to its many desirable properties, including low cost, ease of processing, and sterilization. 13 It finds extensive use in the biomedical field 14 as filtration membranes, 15 textiles/fabrics, and medical implants such as surgical meshes 16,17 and vascular prostheses. 18 These applications necessitate extraordinary wettability and protein repellency. 19 Wettability results from hydrophilic functional groups binding or interacting via H-bonding to water (H 2 O) molecules, leading to the formation of a highly hydrated layer of H 2 O molecules surrounding the hydrophilic groups. This hydrated layer results in steric hindrance to any incoming protein molecules, preventing their adsorption. 20Additional Supporting Information may be found in the online version of this article.