Association and Structure of Thermosensitive Comblike Block Copolymers in Aqueous Solutions

Abstract

The structures and association properties of thermosensitive block copolymers of poly(methoxyoligo(ethylene glycol) norbornenyl esters) in D 2 O were investigated by small angle neutron scattering (SANS). Each block is a comblike polymer with a polynorbornene (PNB) backbone and oligo ethylene glycol (OEG) side chains (one side chain per NB repeat unit). The chemical formula of the block copolymer is (OEG 3 NB) 79 -(OEG 6.6 NB) 67 , where subscripts represent the degree of polymerization (DP) of OEG and NB in each block. The polymer concentration was fixed at 2.0 wt % and the structural changes were investigated over a temperature range between 25 and 68°C. It was found that at room temperature polymers associate to form micelles with a spherical core formed by the block (OEG 3 NB) 79 and corona formed by the block (OEG 6.6 NB) 67 and that the shape of the polymer in the corona could be described by the form factor of rigid cylinders. At elevated temperatures, the aggregation number increased and the micelles became more compact. At temperatures around the cloud point temperature (CPT) T ) 60°C a correlation peak started to appear and became pronounced at 68°C due to the formation of a partially ordered structure with a correlation length ∼349 Å.

The thermo responsive behavior of glycol functionalized ring opening metathesis polymers

“…The difunctionalized norbornene derivative 4 gave polymers with a number average molecular weight of about 40 kg mol −1 independent from the used monomer to initiator ratio. Comparing this value with published results on oligo‐ethylene glycol functionalized polymers, with more than 3 repeating units, it became clear, that this is the highest molecular weight ever reported for such polymers 47. Presumably, polymerization is hampered at a certain degree by the steric conditions imposed by the polymer chain attached to the initiator.…”

“…Oligo(ethylene glycol) esters of norbornenes were anticipated to execute both requirements based on literature reports on ATRP of corresponding acrylate derivatives 40–44. However, research on ROMP as the polymerization method and using properly functionalized norbornenes is still in its infancy 45–47…”

ZK‐5: A CO2‐Selective Zeolite with High Working Capacity at Ambient Temperature and Pressure

“…Moreover, they have inherent advantages as compared to traditional PNIPAM such as: (i) an excellent bio‐repellency below LCST (i.e., anti‐fouling behavior), (ii) reversible phase transitions (i.e., no marked hysteresis), and (iii) bio‐inert properties (i.e., no specific interactions with biological materials). Furthermore, although oligo(ethylene glycol) pendant chains can be connected to various types of polymeric backbones,18, 27–29 the polymerization of oligo(ethylene glycol) (meth)acrylates is surely the most effective strategy for preparing thermoresponsive polymers 17. Indeed, most of these methacrylate derivatives (Figure 1) are commercial products and are therefore readily available for materials science 17.…”

Design of Oligo(ethylene glycol)-Based Thermoresponsive Polymers: an Optimization Study

“…The latter family is composed of different sub-classes. For instance, oligo(ethylene glycol)-grafted polymers based on poly(vinyl ether) [14,15], polynorbornene [16], polyester [17], polystyrene [18,19], polyacrylate [20][21][22], or polymethacrylate [23][24][25][26] backbones were all reported to exhibit a LCST in water. This thermoresponsive behavior is believed to be related to the amphiphilic character of these polymers [27,28].…”