For the stabilization of complex bone fractures, tissue adhesives are an attractive alternative to conventional implants, often consisting of metal plates and screws whose fixation may impose additional trauma on the already fractured bone. This study reports on the synthesis and evaluation of activated dopamine derivatives as primers for fiber-reinforced-adhesive patches in bone-fracture stabilization strategies. The performance of synthesized dopamine derivatives are evaluated with regard to the adhesive shear strength of formed bone patches, as well as cell viability and surface properties. Dopamine-derived primers with methacrylamide, allyl, and thiol functional groups were found to significantly increase the adhesive shear strength of adhesive patches. Furthermore, deprotonation of the primer solution was determined to be essential in order to achieve good adhesion. In conclusion, the primer solutions that were found to give the best adhesion were the once where dopa-thiol was used in combination with either dopamethacrylamide or dopa-allyl, resulting in shear bond strengths of 0.29 MPa.

Since extraction of the naturally occurring mussel-foot proteins is expensive and time-consuming, routes towards synthetic analogues are continuously being explored. Often, these methods involve several protection and deprotection steps, making the synthesis of synthetic analogues time-consuming and expensive as well. Herein, we show that UV-initiated thiol-ene coupling between a thiol-functional dopamine derivative and an allyl-functional aliphatic polycarbonate can be used as a fast and facile route to dopa-functional materials. Different thiol-to-allyl ratios and irradiation protocols were used and it was found that nearly 50% of the allyl groups could be functionalized with dopa within short reaction times, without the need of protecting the catechol. It is also demonstrated herein that the dopa-functional polymers can be used to form self-healing gels through complexation with Fe3+ ions at increased pH.

By combining ATRP, dendrimer chemistry and 'click' reactions, a library of novel linear dendritic block copolymers (hybrids) was successfully synthesized. The isolated polymers displayed hydrophilic alkyne groups and T-g's ranging from 14 degrees C to 67 degrees C. A T-g threshold of 39 degrees C was found necessary for straightforward porous membrane fabrication via the breath figure method. Exploiting the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction, a robust and benign protocol was identified enabling surface functionalization under aqueous conditions. Such manipulations included the introduction of fluorescent rhodamine for thorough assessment by confocal fluorescence microscopy as well as polyethylene glycol chains or perfluorinated groups for tuning the membrane wettability. Finally, with the initial indication of being nontoxic to human dermal fibroblasts (hDF) and osteoblast-like MG63, the porous membranes can potentially find use in the field of controlled cell culture such as patterning of cell growth.

Itaconic acid is a platform compound for bio-based renewable materials. This study employs itaconic anhydride (IAn) as a novel monomer for lipase-catalyzed ring-opening addition condensation polymerization (ROACP) involving dehydration to produce reactive polyesters. ROACP reactions were conducted by combining a cyclic anhydride and a diol. IAn, succinic anhydride (SAn) and glutaric anhydride (GAn) were used as the cyclic anhydrides, and 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol and 1,10-decanediol were used as the diols. ROACP between two monomers, IAn and a diol, did not occur. Model reactions using IAn and n-octyl alcohol provided useful information about the regioselectivity and substrate selectivity of IAn. ROACP using three monomer components, IAn, SAn or GAn, and a diol, produced polyesters in good-to-high yields. From the SAn reactions, polyesters with M-n values of 650-3510 with 1.3-2.6 IAn units per molecule were obtained. From the GAn reactions, these values were 560-3690 and 1.2-3.1, respectively. The crosslinking reaction of a product polyester showed its reactive nature, giving a crosslinked hard solid polyester. The present polyesters derived from renewable starting materials have potential applications as macromonomers, telechelics, or crosslinking reagents, and the benign character of the ROACP reaction makes it appropriate for green polymer chemistry.

In this work, photo-induced thiol-ene coupling (TEC) was used to produce well-defined poly(ethylene glycol) (PEG)-based hydrogels. PEGs of four different molecular weights (2k, 6k, 10k, and 20k) were functionalized with G1-allyl dendrons using anhydride chemistry to produce tetra-functional TEC crosslinkable PEGs. The tetra-functional PEGs were subsequently crosslinked with a tri-functional thiol in ethanol to form hydrogels. The synthesized hydrogels were characterized with respect to swelling behaviour, rheological properties and hydrolytic degradation. It was found that the molecular weight of the PEG chain greatly influences the final properties of the hydrogel, where a higher molecular weight of PEG gives an increased weight swelling ratio from 240% for PEG-2k hydrogels to 1400% for PEG-20k hydrogels, as well as decreased elastic moduli, with Young's moduli ranging from 106 MPa to 6 MPa, for PEG-2k and PEG-20k hydrogels, respectively. It was also found that the hydrolytic stability in alkaline conditions (pH 10) decreased when the molecular weight of PEG in the hydrogels increased.

The development of a facile method for the fabrication of breath figure (BF) films from hydrophobic polymers is gaining significant importance for their accessibility as templates in fields ranging from electronics and cell culturing to sensing and catalysis. By introducing polyester-based dendritic linkers, a library of micrometre sized honeycomb structures was successfully fabricated from amphiphilic linear-dendritic-linear hybrids comprising hydrophobic PCL or PLA and hydrophilic PEG blocks. From the array of produced films, the incorporation of a third generation dendritic linker was found to generate well-ordered honeycomb films in the several hundreds of micrometre range. This one component approach minimizes the number of unknown parameters and represents a fully reliable methodology for the fabrication of functional BFs from challenging and biocompatible polymers.

Emerging dendritic-linear-dendritic (DLD) hybrids that possess synergetic properties of linear and highly functional branched dendritic polymers are becoming important macromolecular scaffolds in fields ranging from biomedicine to nanotechnology. By exploiting pseudo-one-step polycondensation reactions, a facile and scalable synthetic methodology for the construction of highly functional DLDs has been developed. A library of three sets of DLDs exhibiting a hydrophilic linear PEG core with covalently attached hyperbranched bis-MPA blocks was synthesized up to the seventh generation with 256 reactive peripheral hydroxyl groups. The degree of branching for the hybrids was found between 0.40 and 0.59 with dispersities ranging from 1.03 to 1.88. The introduction of hyperbranched components resulted in control over or even full disruption of the crystallinity of the PEG. Postfunctionalizations of the peripheral hydroxyl groups with azides, allyls, and ATRP initiators yielded reactive intermediates. These intermediates were successfully assessed through UV-initiated thiol-ene coupling reactions for the synthesis of charged hybrids. ATRP of styrene from the pheriphery afforded amphiphilic macromolecules. Finally, their scaffolding capacity was evaluated for the fabrication of 3D networks, i.e, novel dendritic hydrogels and highly ordered breath figures.

Radical copolymerization based on acrylonitrile (AN) and 2,2,2-Trifluoroethyl acrylate (ATRIF) initited by AIBN was investigated in acetonitrile solution. The resulting poly(AN-co-ATRIF) copolymers were characterized by 1 H, 13 C, and 19 F NMR and IR spectroscopy, and size exclusion chromatography (SEC). Their compositions were assessed by 1 H NMR. The kinetics of radical copolymerization of AN with ATRIF was investigated from sereval experiments achieved at 70 degrees C from initial [AN](0)/[ATRIF](0) molar ratios ranging between 20/80 and 80/20 and was enabled to determine the reactivity ratios of both comonomers. From the monomer-polymer copolymerization curve, the Fineman-Ross and Kelen-Tudos laws enabled to assess the reactivity ratios (r(AN) = r(1) = 1.25 +/- 0.04 and r(ATRIF) = r(2) = 0.93 +/- 0.05 at 70 degrees C) while the revised patterns scheme led to r(12) = r(AN) = 1.03, and r(21) = r(ATRIF) = 0.78 at 70 degrees C. In all cases, rAN x rATRIF product was close to unity, which indicates that poly(AN-co-ATRIF) copolymers exhibit a random structure. This was also confirmed by the Igarashi's and Pyun's laws which revealed the presence of AN-ATRIF, AN-AN, and ATRIF-ATRIF dyads. The Q and e values for ATRIF were also assessed (Q(2) = 0.62 and e(2) = 0.93). The glass transition temperature values, Tg, of these copolymers increased from 17 to 61 degrees C as the molar percentage of ATRIF decreased from 77 to 16% in the copolymer. Thermogravimetry analysis of poly(AN-co-ATRIF) copolymers showed a good thermal stability compared to that of poly(ATRIF) homopolymer due to incorporation of AN comonomer.

Poly(ethylene glycol) (PEG)-diallyls, ranging from 2 to 8 kDa, were successfully reacted with a trifunctional thiol crosslinker via thiol–ene coupling reaction to construct four different primary PEG hydrogels. These systems were used as scaffolds for the preparation of a library of sequential interpenetrating networks (SeqIPNs). The solid content of the secondary networks varied between 21 and 34% and was dependent on the length of the absorbing PEGs. The gel fractions for the IPNs were above 85%. Additionally, the lowest degree of swelling was found for the IPN based on 2-kDa PEG (315%), whereas the 8-kDa PEG IPN exhibited a value of 810%. The SeqIPN strategy facilitated hydrogel systems that cover a larger domain of tensile modulus (192–889 kPa) when compared with single hydrogel networks (175–555 kPa).