From nano to the macro: tuning hierarchical aggregation of thermoresponsive PEG/PCL-based polyurethanes via molar mass/composition control

Amphiphilic hyperbranched polyurethanes (HPUs) based on PEG and PCL are promising for several biomedical applications. However, the lack of control over the molar mass and composition hinders a deep understanding of the aqueous self-assembly of HPUs. In this paper, the control over the HPU molar mass and composition was provided by dynamic urea bond-mediated polymerization (DUBMP), enabling a careful evaluation of their aqueous self-assembly by 1H NMR, DLS, and Cryo-TEM. HPUs containing a single PCL block per chain self-assemble into nanoaggregates (Rh ≈ 10 nm) in water up to its cloud-point temperature (Tcp) of 34 °C. On the other hand, HPUs with more than one PCL block per chain self-assemble into nanoaggregates and their clusters below Tcp. In this case, the solution behavior can be tuned by the HPU molar mass. Increasing Mw¯¯¯¯¯¯¯¯ from 4 to 19 kDa, HPUs of similar composition can form colloidally stable cluster suspensions (Mw¯¯¯¯¯¯¯¯ = 4 kDa) and phase separate into a denser liquid aggregate–cluster phase (Mw¯¯¯¯¯¯¯¯ = 7 kDa) or into a highly viscous aggregate-network phase (Mw¯¯¯¯¯¯¯¯ = 19 kDa). This type of control over the hierarchical aggregation of HPUs was reported for the first time and is interesting for biomedical applications

Bio-based non-isocyanate poly(hydroxy urethane)s (PHU) derived from vanillin and CO₂

As an alternative to the use of hazardous phosgene-based isocyanates for polyurethane preparation, non-isocyanate poly(hydroxy urethanes) (PHU) based on 5-membered cyclic carbonates have been developed. However, to date, most aromatic PHUs are oil-based or based on toxic precursors such as bisphenol-A. In this work, bio-based non-isocyanate poly(hydroxy urethanes) (PHUs) prepared from vanillin are reported for the first time. First, three different vanillin-derived bis-cyclic carbonates were synthesized. Subsequently, each monomer was reacted with two different bis-amines to yield six different PHUs, which were characterized in depth by 1H and 13C NMR spectroscopy, FTIR, SEC and DSC. PHUs based on vanillic acid were found to exhibit thermal properties superior to bisphenol A-based PHUs, with a Tg of around 66 °C. It is envisioned that vanillin-based PHUs could potentially be a safer alternative to harmful bisphenol A-based PHUs and provide a useful strategy for CO2 revalorization, especially considering that vanillin is an abundant byproduct of Kraft lignin production

Amphiphilic polyurethane hydrogels as smart carriers for acidic hydrophobic drugs

Amphiphilic hydrogels are widely reported as systems with great potential for controlled drug release. Nevertheless, themajority ofstudies makeuse offunctionalization orattachment ofdrugs to thepolymer chains. In this study, we propose a strategy of combining amphiphilic polyurethanes with pH-responsive drugs to develop smart drug carriers. While the amphiphilic character of the polymer imparts an efficient load of hydrophobic and hydrophilic drugs, the drug’s characteristics determine the selectivity of the medium delivery. Drug loading and release behavior as well as hydrolytic degradation ofchemically crosslinked polyurethane hydrogels based on PEG and PCL-triol (PU (polyurethane) hydrogels) synthesized by an easy one-pot route were studied. PU hydrogels have been shown to successfully load the hydrophobic acidic drug sodium diclofenac, reaching a partition coefficient of 8 between the most hydrophobic PU and diclofenac/ethanol solutions. Moreover, an oral administration simulation was conducted by changing the environment from an acidic to a neutral medium. PU hydrogels release less than 5% of the drug in an acidic medium; however, in a PBS pH 7.4 solution, diclofenac is delivered in a sustained fashion for up to 40h, achieving 80% of cumulative release5461-2106114CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP444392/2014-92010/17804-7; 2015/25406-

ABS composites with cellulose fibers: Towards fiber-matrix adhesion without surface modification

Aiming for a cost-effective and environmentally friendly material, we propose the replacement of glass fiber/poly(acrylonitrile-co-butadiene-co-styrene) (ABS) composites by composites with cellulosic reinforcing agents. Industrial production of these composites is hindered by high cost and/or fiber surface modification methods. We report that 30% in weight (wt. %) of pristine cellulose fibers (CF) are highly adherent to an ABS matrix, as verified by microscopy. This provides an overall enhancement of 20% in tensile and flexural mechanical properties. Fiber/matrix adhesion derives from the oxidation of polybutadiene (PB) segments during extrusion, which generates epoxide groups that react with hydroxyls from CF to form ether bonds. We used additives for testing improvement of fiber/matrix adhesion. The addition of XIBOND™ 160 (maleic anhydride grafted polystyrene) reduces fiber/matrix adhesion due to the competition between the grafting of cellulose fibers onto PS segments of the additive and PB domains of ABS. Lignin catalyzes the epoxide reaction with hydroxyls, which leads to improvements in flexural mechanical properties. Overall, ca. 20 wt. % of ABS can be effectively saved by adding 30 wt. % of CF, with improvement of mechanical properties. The density of the composites is 1.3 g cm−3, similar to glass fiber/ABS composite densities. Therefore, CF is effective as a reinforcing filler for ABS, reducing cost and improving mechanical properties

Macroporous hydrogels based on carbohydrates monomethacrylates and dimethacrylates: singular properties from carbohydrate‐based crosslinkers

FAPESP – FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ – CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOReadily available feedstock and biocompatibility make carbohydrate‐based hydrogels promising materials for biomedical applications. However, carbohydrate‐based crosslinkers are rather underexplored when compared with crosslinkers derived from fossil resources. In this study, novel fully bio‐based hydrogels derived from enzymatically produced d‐fructose and d‐glucose methacrylate monomers were synthesized with different amounts of d‐fructose dimethacrylate crosslinker. The use of a carbohydrate‐based crosslinker endows hydrogels with high swelling coefficients, up to 2400%, and superior mechanical resistance (compressive modulus up to 9.5 kPa with a maximum stress up to 50 kPa) compared with conventional crosslinkers based on fossil resources. Hydrogels shape and crosslinking density influences hydrogel morphology, swelling behavior and mechanical resistance. Moreover, hydrogels presented cell viability, biodegradability and hydrolysis‐resistance over a wide range of pH. The use of a highly hydrophilic crosslinker based on carbohydrate for hydrogels synthesis enables the use of high crosslinker concentration, which improves mechanical properties, however with minor loss of the water swelling capacity, compared with conventional fossil‐based crosslinkers. This is an important advantage over conventional crosslinkers based on fossil resources. Moreover, slab hydrogels hold higher stress under compression–decompression cycles, and present higher resistance to hydrolysis in basic medium due to the thicker pore walls than cylindrical ones94619131924FAPESP – FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ – CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP – FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ – CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO2014/14232-3; 2010/17804-7; 2015/25406-5444392/2014-

Implementation of a Brazilian Cardioprotective Nutritional (BALANCE) Program for improvement on quality of diet and secondary prevention of cardiovascular events: A randomized, multicenter trial

Background: Appropriate dietary recommendations represent a key part of secondary prevention in cardiovascular disease (CVD). We evaluated the effectiveness of the implementation of a nutritional program on quality of diet, cardiovascular events, and death in patients with established CVD. Methods: In this open-label, multicenter trial conducted in 35 sites in Brazil, we randomly assigned (1:1) patients aged 45 years or older to receive either the BALANCE Program (experimental group) or conventional nutrition advice (control group). The BALANCE Program included a unique nutritional education strategy to implement recommendations from guidelines, adapted to the use of affordable and regional foods. Adherence to diet was evaluated by the modified Alternative Healthy Eating Index. The primary end point was a composite of all-cause mortality, cardiovascular death, cardiac arrest, myocardial infarction, stroke, myocardial revascularization, amputation, or hospitalization for unstable angina. Secondary end points included biochemical and anthropometric data, and blood pressure levels. Results: From March 5, 2013, to Abril 7, 2015, a total of 2534 eligible patients were randomly assigned to either the BALANCE Program group (n = 1,266) or the control group (n = 1,268) and were followed up for a median of 3.5 years. In total, 235 (9.3%) participants had been lost to follow-up. After 3 years of follow-up, mean modified Alternative Healthy Eating Index (scale 0-70) was only slightly higher in the BALANCE group versus the control group (26.2 ± 8.4 vs 24.7 ± 8.6, P <.01), mainly due to a 0.5-serving/d greater intake of fruits and of vegetables in the BALANCE group. Primary end point events occurred in 236 participants (18.8%) in the BALANCE group and in 207 participants (16.4%) in the control group (hazard ratio, 1.15; 95% CI 0.95-1.38; P =.15). Secondary end points did not differ between groups after follow-up. Conclusions: The BALANCE Program only slightly improved adherence to a healthy diet in patients with established CVD and had no significant effect on the incidence of cardiovascular events or death. © 2019 The Author