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Teekkarikylä, Finland

Alhoranta A.M.,Laboratory of Polymer Chemistry | Lehtinen J.K.,Center for Drug Research | Urtti A.O.,Center for Drug Research | Butcher S.J.,University of Helsinki | And 2 more authors.
Biomacromolecules | Year: 2011

A series of amphiphilic star and linear block copolymers were synthesized using ATRP. The core consisted of either polystyrene (PS) or poly(n-butyl acrylate) (PBuA), having different glass-transition (T g) values. These polymers were used as macroinitiators in the polymerization of the cationic 2-(dimethylamino)ethyl methacrylate (DMAEMA). The polymers were used to study the effects of polymer architecture and flexibility on the self-assembling properties, DNA complexation, and transfection. All polymers formed core-shell micelles in aqueous solutions and condensed plasmid DNA. Linear PDMAEMA-PBuA-PDMAEMA has transfection efficiency comparable to PEI25K in ARPE19 cell line. Glassy state of the micellar core and star-shaped architecture decreased the DNA transfection compared with the rubbery and linear polymer structures. The polymers showed low cellular toxicity at low nitrogen/phosphate (n/p) ratios. © 2011 American Chemical Society. Source


Parviainen H.,Laboratory of Polymer Chemistry | Parviainen A.,Laboratory of Organic Chemistry | Virtanen T.,Laboratory of Polymer Chemistry | Kilpelainen I.,Laboratory of Organic Chemistry | And 5 more authors.
Carbohydrate Polymers | Year: 2014

In this work, interactions between cellulose and ionic liquids were studied calorimetrically and by optical microscopy. Two novel ionic liquids (1,5-Diazabicyclo[4.3.0]non-5-enium propionate and N-methyl-1,5-diazabicyclo[4. 3.0]non-5-enium dimethyl phosphate) and 1-ethyl-3-methylimidazolium acetate-water mixtures were used as solvents. Optical microscopy served in finding the extent of dissolution and identifying the dissolution pattern of the cellulose sample. Calorimetric studies identified a peak relating to dissolution of cellulose in solvent. The transition did, however, not indicate complete dissolution, but rather dissolution inside fibre or fibrils. This method was used to study differences between four cellulose samples with different pretreatment or origins. © 2014 Elsevier Ltd. Source


Ramanen P.,Laboratory of Polymer Chemistry | Maunu S.L.,Laboratory of Polymer Chemistry
Progress in Organic Coatings | Year: 2014

One- and two-dimensional NMR spectroscopy was used to evaluate the structure of tall oil fatty acid (TOFA)-based alkyd resins and waterborne alkyd-acrylic copolymers. An increase in the functionality of the polyol that is used in the alkyd resin synthesis was found to increase the reactivity of the polyol towards the diacid compared with the TOFA, which causes the formation of more branched and higher molar mass alkyd resin structures. During the copolymerization, polyacrylate chains were grafted to the double bonds and allylic sites of the fatty acid chains in the alkyd resin. Butyl acrylate preferentially grafted to the double bonds, while methyl methacrylate tended to graft to the allylic position. High proportions of the double bonds remaining after copolymerization were crucial to the film formation of copolymers, because the chemical drying of copolymer films occurred by an autoxidation process. © 2013 Published by Elsevier B.V. All rights reserved. Source

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