We have prepared polyurethane with poly(e-caprolactone) (PCL) as the segments of the main chain and poly(triisopropylsilyl acrylate) (PTIPSA) as the side chains by a combination of radical polymerization and a condensation reaction. Quartz crystal microbalance with dissipation studies show that polyurethane can degrade in the presence of enzyme and the degradation rate decreases with the PTIPSA content. Our studies also demonstrate that polyurethane is able to hydrolyze in artificial seawater and the hydrolysis rate increases as the PTIPSA content increases. Moreover, hydrolysis leads to a hydrophilic surface that is favorable to reduction of the frictional drag under dynamic conditions. Marine field tests reveal that polyurethane has good antifouling ability because polyurethane with a biodegradable PCL main chain and hydrolyzable PTIPSA side chains can form a self-renewal surface. Polyurethane was also used to carry and release a relatively environmentally friendly antifoulant, and the combined system e...

Marine Biofouling Resistance of Polyurethane with Biodegradation and Hydrolyzation

Amide-containing segmented copolymers

The reaction of FeCl3 with a pincer ligand, 2,6-di(1H-pyrazol-3-yl)pyridine (bppyH2), produced a mononuclear Fe(III) complex [Fe(bppyH2)Cl3] (1), which could be reduced to the corresponding Fe(II) dichloride complex [Fe(bppyH2)Cl2] (2) by suitable reducing agents such as Cp2Co or Fe powder. 1 and 2 exhibited a reversible transformation from each other with appropriate redox reagents. 1 could be utilized as a pre-catalyst to initiate the ring-opening polymerization of e-caprolactone in the presence of alcohol but 2 did not work. The 1/alcohol system displayed characteristics of a well-controlled polymerization with the resulting poly(e-caprolactone) having low molecular weight distributions, a linear tendency of molecular weight evolution with conversion, and polymer growth observed for the sequential additions of e-caprolactone monomer to the polymerization reaction. The polymerization was completely turned off by the in situ reduction of the catalytic Fe center via Cp2Co and then turned back upon the addition of [Cp2Fe]PF6. The rate of polymerization was modified by switching in situ between the Fe(III) and Fe(II) species.

Synthesis and structure of a ferric complex of 2,6-di(1H-pyrazol-3-yl)pyridine and its excellent performance in the redox-controlled living ring-opening polymerization of ε-caprolactone

With the general objective to design polymer based materials with specific thermal and mechanical properties, a systematic study on the crystallinity and the mechanical properties of synthesized linear tri-block copolymers based on poly(L-lactic acid) and poly(e-caprolactone) and of their corresponding poly(ester-urethane)s has been performed. In particular, eleven tri-block copolymers were synthesized varying both the molecular weight of the blocks as well as the relative content of each block in the copolymer, focusing the attention on the relationship between their chemical compositions and their tailored final properties in order to tune them taking into account their possible applications (i.e. as shape memory materials). From them, eleven poly(ester-urethane)s were synthesized by condensation with hexamethylene diisocyanate (HDI). The chemical composition of the synthesized polymers was studied and correlated with their thermal and crystalline properties obtained by both dynamic scanning calorimetry (DSC) and small angle X-ray diffraction (SAXS) experiments. The relationship between their crystalline structure, thermal and mechanical properties with the molecular weight as well as with the relative content of each comonomer in the copolymers and the amount of HDI in the poly(ester-urethane) was analysed. The results obtained demonstrate that these bio tri-block copolymers and the corresponding poly(ester-urethane)s can be tailored with interesting crystalline and mechanical properties. Future applications as shape memory systems are thus envisaged.

/pdf/synthesis-of-plla-b-pcl-b-plla-linear-tri-block-copolymers-13ymj13k5f.pdf

Synthesis of PLLA-b-PCL-b-PLLA linear tri-block copolymers and their corresponding poly(ester-urethane)s: effect of the molecular weight on their crystallisation and mechanical properties

Different hard segment content (HSC) polyurethanes (PUs) have been synthesized using linear (hexamethylene diisocyanate; HMDI) and alicyclic (isophorone diisocyanate; IPDI) diisocyanates to understand the effect on structure–property relationship and how it affects the shape memory behavior of PUs. Structural details have been elucidated through NMR and other spectroscopic techniques including the quantification of HSC. The nature of interactions between the polymer chains and their extent has been revealed. Thermal and mechanical properties as a function of the chemical structure and HSC indicate faster degradation in higher HSC. Layer-by-layer self-assembly through extensive hydrogen bonding has been established through XRD, small-angle neutron scattering, AFM, and optical images by capturing nanometer scale to micron scale inhomogeneities. The greater interaction in the HMDI system as compared to IPDI PUs leads to the crystallization of the hard segment. The differential shape memory effect has been re...

Nanostructure-Controlled Shape Memory Effect in Polyurethanes

Twenty seven poly(ester–urethane–amide)s (PEUAs) were synthesized from the reaction of α,ω-telechelic poly(e-caprolactone) diols, 1,6-hexamethylene diisocyanate, and three different diamide–diol chain extenders derived from e-caprolactone and three aliphatic diamines with increasing length (n = 2, 4, and 6). The hard segment (HS) was designed to be crystalline and to introduce amide groups, more susceptible to hydrolysis than urethane or urea groups. Crystallization of the HS was achieved even at very low HS content, leading to a phase-separated material. Furthermore, HS crystallinity recovered from the material homogeneous melt on cooling. Thermal degradation was well above HS melting point, allowing for melt processing of these materials. HS melting point was affected by HS content, poly(e-caprolactone) diol length, and chain extender length. The length scale of the phase-separated morphology lied in between 11 and 13 nm up to ∼60% HS content and decreased at higher HS content values. HS content was the...

Biodegradable Poly(ester−urethane−amide)s Based on Poly(ε- caprolactone) and Diamide−Diol Chain Extenders with Crystalline Hard Segments. Synthesis and Characterization

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Biodegradable Poly(ester−urethane−amide)s Based on Poly(ε- caprolactone) and Diamide−Diol Chain Extenders with Crystalline Hard Segments. Synthesis and Characterization