The morphological changes of phosphonate polypeptoid electrolyte membranes, poly-N-(2-ethyl)hexylglycine-block-poly-N-phosphonomethylglycine (pNehm-b-pNpmn), in hydrated and dry states were characterized by cryogenic transmission electron microscopy (cryo-TEM) and cryogenic electron tomography (cryo-ET). The analysis of 3D tomograms revealed that the pNeh9-b-pNpm9 thin films absorbed a large amount of water, resulting in the formation of membranes that were nearly flat and giant multicompartment vesicles dispersed in the water phase. A simple lamellar phase appeared when the films were dried. In contrast, pNeh18-b-pNpm18 thin films absorbed little water and formed small highly curved unilamellar and multilamellar vesicles. Water was located mainly outside the closely-packed vesicles. When water was removed by drying, the walls of adjacent vesicles collapsed to form honeycomb-like capsules. The changes in domain size reflected changes in chain conformations. The pNpm9 blocks were saturated by water and fully extended, while pNpm18 blocks were neither saturated by water nor fully extended. In addition, the thicknesses of hydrophobic blocks in the hydrated films of both pNeh9-b-pNpm9 and pNeh18-b-pNpm18 were smaller than those in the dry films, reflecting an increase of the average distance between the neighboring junctions of polypeptoid molecules.

Polymers that dissolve and conduct lithium ions are of great interest in the application of rechargeable lithium batteries. It is generally believed that the transport of ions in these systems is facilitated by rapid segmental motion typically found in rubbery, amorphous polymers. In this paper, we demonstrate that chemically identical ethyleneoxy-containing domains of a block copolymer exhibit comparable conductivities when in an amorphous or a crystalline state. An important feature of this study is the use of sequence-defined block copolypeptoids synthesized by submonomer solid-phase synthesis. Two structurally analogous ethyleneoxy-containing diblock copolypeptoids poly-N-(2-ethyl)hexylglycine-block-poly-N-2-(2-(2-methoxyethoxy)ethoxy)ethylglycine (pNeh-b-pNte) and poly-N-decylglycine-block-poly-N-2-(2-(2-methoxyethoxy)ethoxy)ethylglycine (pNdc-b-pNte) with 18 monomer units per block were synthesized. Both diblock copolypeptoids have the same conducting block, pNte, but different nonconducting blocks: pNeh, which is amorphous, and pNdc, which is crystalline. Both diblock copolypeptoids self-assemble into a lamellar morphology; however, pNte chains are amorphous in pNeh-b-pNte and crystalline in pNdc-b-pNte. This provides the platform for comparing lithium ion transport in amorphous and crystalline polymer domains that are otherwise similar.

Background

Diabetes is a chronic medical condition and adherence to medication in diabetes is important. Improving medication adherence in adults with diabetes would help prevent the chronic complications associated with diabetes. A case control trial was used to study the effects of an educational session on medication adherence among adults with diabetes as measured by the Morisky Medication adherence scale (MMAS-8©).

Methods

The study took place at the Dubai Police Health Centre between February 2015 and November 2015. Questionnaires were used to collect socio-demographic, clinical and disease related variables and the primary measure of outcome was adherence levels as measured by the Morisky Medication Adherence Scale (MMAS-8©). The intervention group involved a standardized thirty minute educational session focusing on the importance of adherence to medication. The change in MMAS-8© was measured at 6 months.

Results

Four hundred and forty six patients were enrolled. Mean age 61 year +/- 11. 48.4 % were male. The mean time since diagnosis of diabetes was 3.2 years (Range 1-15 years). At baseline two hundred and eighty eight (64.6 %) patients were considered non-adherent (MMAS-8© adherence score < 6) while 118 (26.5 %) and 40 (9.0 %) had low adherence (MMAS-8© adherence score < 6) and medium adherence (MMAS-8© adherence scores of 6 to 7) to their medication respectively. The percentage of patients scoring low adherence MMAS-8 scores in the interventional group dropped from 64.60 % at baseline to 44.80 % at 6-months (p = 0.01). There was no obvious change in the adherence scores at baseline and at 6-months in the control group. Based on the study data, the Wilcoxon signed-rank test showed that at 6 months, the educational 30-min session on diabetes and adherence to medication did elicit a statistically significant change in adherence levels in adults with diabetes enrolled in the intervention arm (Z = -6.187, p <0.001).

Conclusion

Adults with diabetes would benefit from educational sessions focusing on the importance of adherence to medication. Public health strategies should focus on wider educational strategies targeting medication adherence in diabetic patients in the UAE.

The folding and assembly of sequence-defined polymers into precisely ordered nanostructures promises a class of well-defined biomimetic architectures with specific function. Amphiphilic diblock copolymers are known to self-assemble in water to form a variety of nanostructured morphologies including spheres, disks, cylinders, and vesicles. In all of these cases, the predominant driving force for assembly is the formation of a hydrophobic core that excludes water, whereas the hydrophilic blocks are solvated and extend into the aqueous phase. However, such polymer systems typically have broad molar mass distributions and lack the purity and sequence-defined structure often associated with biologically derived polymers. Here, we demonstrate that purified, monodisperse amphiphilic diblock copolypeptoids, with chemically distinct domains that are congruent in size and shape, can behave like molecular tile units that spontaneously assemble into hollow, crystalline nanotubes in water. The nanotubes consist of stacked, porous crystalline rings, and are held together primarily by side-chain van der Waals interactions. The peptoid nanotubes form without a central hydrophobic core, chirality, a hydrogen bond network, and electrostatic or π-π interactions. These results demonstrate the remarkable structure-directing influence of n-alkane and ethyleneoxy side chains in polymer self-assembly. More broadly, this work suggests that flexible, low-molecular-weight sequence-defined polymers can serve as molecular tile units that can assemble into precision supramolecular architectures.

Microphase-separated block copolymer materials have a wide array of potential applications ranging from nanoscale lithography to energy storage. Our understanding of the factors that govern the morphology of these systems is based on comparisons between theory and experiment. The theories generally assume that the chains are perfectly monodisperse; however, typical experimental copolymer preparations have polydispersity indices (PDIs) ranging from 1.01 to 1.10. In contrast, we present a systematic study of the relationship between chemical structure and morphology in the solid state using peptoid diblock copolymers with PDIs of ≤1.00013. A series of comb-like peptoid block copolymers, poly(N-2-(2-(2-methoxyethoxy)ethoxy)ethylglycine)-block-poly(N-(2-ethylhexyl)glycine) (pNte-b-pNeh), were obtained by solid-phase synthesis. The number of monomers per chain was held fixed at 36, while the volume fraction of the Nte block (ϕNte) was varied from 0.11 to 0.65. The experimentally determined order-disorder transition temperature exhibited a maximum at ϕNte = 0.24, not ϕNte = 0.5 as expected from theory. All of the ordered phases had a lamellar morphology, even in the case of ϕNte = 0.11. Our results are in qualitative disagreement with all known theories of microphase separation in block copolymers. This raises new questions about the intertwined roles of monomer architecture and polydispersity in the phase behavior of diblock copolymers.

The interplay of crystalline packing, which governs atomic length-scale order, and hierarchical assembly, which governs longer length scales, is essential to fabricate complex superstructures from polymers for many applications. Here, we demonstrate that a diblock copolymer containing an N-octylglycine peptoid block, which has a propensity to crystallize, can form distinct hierarchical superstructures including a star-like morphology, a superbrush, or a nanosheet by tuning the balance between surface energy arising from the solubility of the copolymers and crystallization energy of the solvophobic polypeptoid blocks. We show that partially ordered micellar aggregates (clusters) are key intermediates that form early in the assembly process and template the formation of superstructures via the oriented fusion of individual micelles as the growth materials. Notably, the fiber-like branch of the superstructures is driven by crystallization and exhibits growth in a living linear manner. The superstructures can be internalized by mammalian cells and hold promise for biomedical applications.

Atomic level synthetic control over a polymer's chemical structure can reveal new insights into the crystallization kinetics of block copolymers. Here, we explore the impact of side chain structure on crystallization behavior, by designing a series of sequence-defined, highly monodisperse peptoid diblock copolymers poly-N-decylglycine-block-poly-N-2-(2-(2-methoxyethoxy)ethoxy)ethylglycine (pNdc-b-pNte) with volume fraction of pNte (ϕNte) values ranging from 0.29 to 0.71 and polydispersity indices ≤1.00017. Both monomers have nearly identical molecular volumes, but the pNte block is amorphous while the pNdc block is crystalline. We demonstrate by X-ray scattering and calorimetry that all the block copolypeptoids self-assemble into lamellar microphases and that the self-assembly is driven by crystallization of the pNdc block. Interestingly, the microphase separated pNdc-b-pNte diblock copolymers form two distinct crystalline phases. Crystallization of the normally amorphous pNte chains is induced by the preorganization of the crystalline pNdc chains. We hypothesize that this is due to the similarity of chemical structure of the monomers (both monomers have linear side chains of similar lengths emanating from a polyglycine backbone). The pNte block remains amorphous when the pNdc block is replaced by another crystalline block, poly-N-isoamylglycine, suggesting that a close matching of the lattice spacings is required for induced crystallization. To our knowledge, there are no previous reports of crystallization of a polymer chain induced by microphase separation. These investigations show that polypeptoids provide a unique platform for examining the effect of intertwined roles of side chain organization on the thermodynamic properties of diblock copolymers.

Background

Diabetes is a chronic medical condition and adherence to medication in adults with diabetes is important. Identifying predictors to medication adherence in adults with diabetes would help identify vulnerable patients who are likely to benefit by improving their adherence levels.

Methods

We conducted a cross-sectional study at the Dubai Police Health Centre between February 2015 and November 2015. Questionnaires were used to collect socio-demographic, clinical and disease related variables and the primary measure of outcome was adherence levels as measured by the Morisky Medication Adherence Scale (MMAS-8©). Multivariate logistic regression was carried out to identify predictors to adherence.

Results

Four hundred and forty six patients were interviewed. Mean age 61 year +/- 11. 48.4 % were male. The mean time since diagnosis of diabetes was 3.2 years (Range 1-15 years). Two hundred and eighty eight (64.6 %) patients were considered non-adherent (MMAS-8© adherence score < 6) while 118 (26.5 %) had moderate adherence (MMAS-8© adherence score 6 = <8) and 40 (9.0 %) high adherence (MMAS-8© adherence scores <8) to their medication respectively. The strongest predictor for adherence as predicted by the multi-logistic regression model was the patient's level of education. A technical diploma certificate as compared to a primary school level of education was the strongest predictor of adherence (OR = 66.1 CI: 6.93 to 630.43); p < 0.001). The patient's age was also a predictor of adherence with older patients reporting higher levels of adherence (OR = 1.113 (CI: 1.045 to 1.185; p = 0.001 for every year increase in age). The duration of diabetes was also a predictor of adherence (OR = 1.830 (CI: 1.270 to 2.636; p = 0.001 for every year increase in the duration of diabetes). Other predictors to medication adherence include Insulin use, ethnicity and certain cultural behaviours.

Conclusion

A number of important predictors to medication adherence in diabetics were identified in this study. Such predictors could help develop policies for improving adherence in diabetics.